java.lang.Object
- mpi.Comm

All Implemented Interfaces:

java.lang.Cloneable, Freeable

Direct Known Subclasses:

Intercomm, Intracomm
```
public class Comm
extends java.lang.Object
implements Freeable, java.lang.Cloneable
```
The Comm class represents communicators.

Field Summary

Fields
Modifier and Type Field Description

protected long handle

protected static int SELF

static int TYPE_SHARED

protected static int WORLD

Constructor Summary

Constructors
Modifier Constructor Description

protected Comm()

protected Comm(long handle)

protected Comm(long[] commRequest)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`abort(int errorcode)`	Abort MPI.
`void`	`allGather(java.lang.Object buf, int count, Datatype type)`	Similar to `gather`, but all processes receive the result.
`void`	`allGather(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int recvcount, Datatype recvtype)`	Similar to `gather`, but all processes receive the result.
`void`	`allGatherv(java.lang.Object recvbuf, int[] recvcount, int[] displs, Datatype recvtype)`	Similar to `gatherv`, but all processes receive the result.
`void`	`allGatherv(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int[] recvcount, int[] displs, Datatype recvtype)`	Similar to `gatherv`, but all processes receive the result.
`void`	`allReduce(java.lang.Object buf, int count, Datatype type, Op op)`	Same as `reduce` except that the result appears in receive buffer of all process in the group.
`void`	`allReduce(java.lang.Object sendbuf, java.lang.Object recvbuf, int count, Datatype type, Op op)`	Same as `reduce` except that the result appears in receive buffer of all process in the group.
`void`	`allToAll(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int recvcount, Datatype recvtype)`	Extension of `allGather` to the case where each process sends distinct data to each of the receivers.
`void`	`allToAllv(java.lang.Object sendbuf, int[] sendcount, int[] sdispls, Datatype sendtype, java.lang.Object recvbuf, int[] recvcount, int[] rdispls, Datatype recvtype)`	Adds flexibility to `allToAll`: location of data for send is specified by `sdispls` and location to place data on receive side is specified by `rdispls`.
`void`	`allToAllw(java.lang.Object sendBuf, int[] sendCount, int[] sDispls, Datatype[] sendTypes, java.lang.Object recvBuf, int[] recvCount, int[] rDispls, Datatype[] recvTypes)`	Adds more flexibility to `allToAllv`: datatypes for send are specified by `sendTypes` and datatypes for receive are specified by `recvTypes` per process.
`void`	`barrier()`	A call to `barrier` blocks the caller until all process in the group have called it.
`void`	`bcast(java.lang.Object buf, int count, Datatype type, int root)`	Broadcast a message from the process with rank `root` to all processes of the group.
`void`	`bSend(java.lang.Object buf, int count, Datatype type, int dest, int tag)`	Send in buffered mode.
`Prequest`	`bSendInit(java.nio.Buffer buf, int count, Datatype type, int dest, int tag)`	Creates a persistent communication request for a buffered mode send.
`void`	`callErrhandler(int errorCode)`	Calls the error handler currently associated with the communicator.
`Comm`	`clone()`	Duplicates this communicator.
`static int`	`compare(Comm comm1, Comm comm2)`	Compare two communicators.
`Intercomm`	`createIntercomm(Comm localComm, int localLeader, int remoteLeader, int tag)`	Create an inter-communicator.
`static int`	`createKeyval()`	Create a new attribute key.
`void`	`deleteAttr(int keyval)`	Deletes an attribute value associated with a key on a communicator.
`void`	`disconnect()`	Java binding of the MPI operation `MPI_COMM_DISCONNECT`.
`Comm`	`dup()`	Duplicates this communicator.
`protected long`	`dup(long comm)`
`protected long`	`dupWithInfo(long comm, long info)`
`Comm`	`dupWithInfo(Info info)`	Duplicates this communicator with the info object used in the call.
`void`	`free()`	Java binding of the MPI operation `MPI_COMM_FREE`.
`static void`	`freeKeyval(int keyval)`	Frees an attribute key for communicators.
`void`	`gather(java.lang.Object buf, int count, Datatype type, int root)`	Each process sends the contents of its send buffer to the root process.
`void`	`gather(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int recvcount, Datatype recvtype, int root)`	Each process sends the contents of its send buffer to the root process.
`void`	`gatherv(java.lang.Object recvbuf, int[] recvcount, int[] displs, Datatype recvtype, int root)`	Extends functionality of `gather` by allowing varying counts of data from each process.
`void`	`gatherv(java.lang.Object sendbuf, int sendcount, Datatype sendtype, int root)`	Extends functionality of `gather` by allowing varying counts of data from each process.
`void`	`gatherv(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int[] recvcount, int[] displs, Datatype recvtype, int root)`	Extends functionality of `gather` by allowing varying counts of data from each process.
`java.lang.Object`	`getAttr(int keyval)`	Retrieves attribute value by key.
`Errhandler`	`getErrhandler()`	Returns the error handler currently associated with the communicator.
`Group`	`getGroup()`	Return group associated with a communicator.
`Info`	`getInfo()`	Java binding of `MPI_COMM_GET_INFO`.
`java.lang.String`	`getName()`	Return the print name from the communicator.
`int`	`getRank()`	Rank of this process in group of this communicator.
`Request`	`getRequest()`	Returns the associated request to this communicator if it was created using `iDup()`.
`int`	`getSize()`	Size of group of this communicator.
`int`	`getTopology()`	Returns the type of topology associated with the communicator.
`Request`	`iAllGather(java.nio.Buffer buf, int count, Datatype type)`	Similar to `gather`, but all processes receive the result.
`Request`	`iAllGather(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int recvcount, Datatype recvtype)`	Similar to `gather`, but all processes receive the result.
`Request`	`iAllGatherv(java.nio.Buffer buf, int[] count, int[] displs, Datatype type)`	Similar to `gatherv`, but all processes receive the result.
`Request`	`iAllGatherv(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int[] recvcount, int[] displs, Datatype recvtype)`	Similar to `gatherv`, but all processes receive the result.
`Request`	`iAllReduce(java.nio.Buffer buf, int count, Datatype type, Op op)`	Same as `reduce` except that the result appears in receive buffer of all process in the group.
`Request`	`iAllReduce(java.nio.Buffer sendbuf, java.nio.Buffer recvbuf, int count, Datatype type, Op op)`	Same as `reduce` except that the result appears in receive buffer of all process in the group.
`Request`	`iAllToAll(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int recvcount, Datatype recvtype)`	Extension of `allGather` to the case where each process sends distinct data to each of the receivers.
`Request`	`iAllToAllv(java.nio.Buffer sendbuf, int[] sendcount, int[] sdispls, Datatype sendtype, java.nio.Buffer recvbuf, int[] recvcount, int[] rdispls, Datatype recvtype)`	Adds flexibility to `allToAll`: location of data for send is specified by `sdispls` and location to place data on receive side is specified by `rdispls`.
`Request`	`iAllToAllw(java.nio.Buffer sendBuf, int[] sendCount, int[] sDispls, Datatype[] sendTypes, java.nio.Buffer recvBuf, int[] recvCount, int[] rDispls, Datatype[] recvTypes)`	Adds more flexibility to `iAllToAllv`: datatypes for send are specified by `sendTypes` and datatypes for receive are specified by `recvTypes` per process.
`Request`	`iBarrier()`	Nonblocking barrier synchronization.
`Request`	`iBcast(java.nio.Buffer buf, int count, Datatype type, int root)`	Broadcast a message from the process with rank `root` to all processes of the group.
`Request`	`ibSend(java.nio.Buffer buf, int count, Datatype type, int dest, int tag)`	Start a buffered mode, nonblocking send.
`Comm`	`iDup()`	Duplicates this communicator.
`protected long[]`	`iDup(long comm)`
`Request`	`iGather(java.nio.Buffer buf, int count, Datatype type, int root)`	Each process sends the contents of its send buffer to the root process.
`Request`	`iGather(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int recvcount, Datatype recvtype, int root)`	Each process sends the contents of its send buffer to the root process.
`Request`	`iGatherv(java.nio.Buffer recvbuf, int[] recvcount, int[] displs, Datatype recvtype, int root)`	Extends functionality of `gather` by allowing varying counts of data from each process.
`Request`	`iGatherv(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, int root)`	Extends functionality of `gather` by allowing varying counts of data from each process.
`Request`	`iGatherv(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int[] recvcount, int[] displs, Datatype recvtype, int root)`	Extends functionality of `gather` by allowing varying counts of data from each process.
`Request`	`iNeighborAllGather(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int recvcount, Datatype recvtype)`	Java binding of `MPI_INEIGHBOR_ALLGATHER`.
`Request`	`iNeighborAllGatherv(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int[] recvcount, int[] displs, Datatype recvtype)`	Java binding of `MPI_INEIGHBOR_ALLGATHERV`.
`Request`	`iNeighborAllToAll(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int recvcount, Datatype recvtype)`	Java binding of `MPI_INEIGHBOR_ALLTOALL`.
`Request`	`iNeighborAllToAllv(java.nio.Buffer sendbuf, int[] sendcount, int[] sdispls, Datatype sendtype, java.nio.Buffer recvbuf, int[] recvcount, int[] rdispls, Datatype recvtype)`	Java binding of `MPI_INEIGHBOR_ALLTOALLV`.
`Status`	`iProbe(int source, int tag)`	Check if there is an incoming message matching the pattern specified.
`Request`	`iRecv(java.nio.Buffer buf, int count, Datatype type, int source, int tag)`	Start a nonblocking receive.
`Request`	`iReduce(java.nio.Buffer buf, int count, Datatype type, Op op, int root)`	Combine elements in input buffer of each process using the reduce operation, and return the combined value in the output buffer of the root process.
`Request`	`iReduce(java.nio.Buffer sendbuf, java.nio.Buffer recvbuf, int count, Datatype type, Op op, int root)`	Combine elements in input buffer of each process using the reduce operation, and return the combined value in the output buffer of the root process.
`Request`	`iReduceScatter(java.nio.Buffer buf, int[] counts, Datatype type, Op op)`	Combine elements in input buffer of each process using the reduce operation, and scatter the combined values over the output buffers of the processes.
`Request`	`iReduceScatter(java.nio.Buffer sendbuf, java.nio.Buffer recvbuf, int[] recvcounts, Datatype type, Op op)`	Combine elements in input buffer of each process using the reduce operation, and scatter the combined values over the output buffers of the processes.
`Request`	`iReduceScatterBlock(java.nio.Buffer buf, int count, Datatype type, Op op)`	Combine values and scatter the results.
`Request`	`iReduceScatterBlock(java.nio.Buffer sendbuf, java.nio.Buffer recvbuf, int recvcount, Datatype type, Op op)`	Combine values and scatter the results.
`Request`	`irSend(java.nio.Buffer buf, int count, Datatype type, int dest, int tag)`	Start a ready mode, nonblocking send.
`Request`	`iScatter(java.nio.Buffer buf, int count, Datatype type, int root)`	Inverse of the operation `gather`.
`Request`	`iScatter(java.nio.Buffer sendbuf, int sendcount, Datatype sendtype, java.nio.Buffer recvbuf, int recvcount, Datatype recvtype, int root)`	Inverse of the operation `gather`.
`Request`	`iScatterv(java.nio.Buffer sendbuf, int[] sendcount, int[] displs, Datatype sendtype, int root)`	Inverse of the operation `gatherv`.
`Request`	`iScatterv(java.nio.Buffer sendbuf, int[] sendcount, int[] displs, Datatype sendtype, java.nio.Buffer recvbuf, int recvcount, Datatype recvtype, int root)`	Inverse of the operation `gatherv`.
`Request`	`iScatterv(java.nio.Buffer recvbuf, int recvcount, Datatype recvtype, int root)`	Inverse of the operation `gatherv`.
`Request`	`iSend(java.nio.Buffer buf, int count, Datatype type, int dest, int tag)`	Start a standard mode, nonblocking send.
`boolean`	`isInter()`	Test if this communicator is an inter-communicator.
`boolean`	`isNull()`	Test if communicator object is null (has been freed).
`Request`	`isSend(java.nio.Buffer buf, int count, Datatype type, int dest, int tag)`	Start a synchronous mode, nonblocking send.
`void`	`neighborAllGather(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int recvcount, Datatype recvtype)`	Java binding of `MPI_NEIGHBOR_ALLGATHER`.
`void`	`neighborAllGatherv(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int[] recvcount, int[] displs, Datatype recvtype)`	Java binding of `MPI_NEIGHBOR_ALLGATHERV`.
`void`	`neighborAllToAll(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int recvcount, Datatype recvtype)`	Java binding of `MPI_NEIGHBOR_ALLTOALL`.
`void`	`neighborAllToAllv(java.lang.Object sendbuf, int[] sendcount, int[] sdispls, Datatype sendtype, java.lang.Object recvbuf, int[] recvcount, int[] rdispls, Datatype recvtype)`	Java binding of `MPI_NEIGHBOR_ALLTOALLV`.
`int`	`pack(java.lang.Object inbuf, int incount, Datatype type, byte[] outbuf, int position)`	Packs message in send buffer `inbuf` into space specified in `outbuf`.
`int`	`packSize(int incount, Datatype type)`	Returns an upper bound on the increment of `position` effected by `pack`.
`Status`	`probe(int source, int tag)`	Wait until there is an incoming message matching the pattern specified.
`Status`	`recv(java.lang.Object buf, int count, Datatype type, int source, int tag)`	Blocking receive operation.
`Prequest`	`recvInit(java.nio.Buffer buf, int count, Datatype type, int source, int tag)`	Creates a persistent communication request for a receive operation.
`void`	`reduce(java.lang.Object buf, int count, Datatype type, Op op, int root)`	Combine elements in input buffer of each process using the reduce operation, and return the combined value in the output buffer of the root process.
`void`	`reduce(java.lang.Object sendbuf, java.lang.Object recvbuf, int count, Datatype type, Op op, int root)`	Combine elements in input buffer of each process using the reduce operation, and return the combined value in the output buffer of the root process.
`static void`	`reduceLocal(java.lang.Object inBuf, java.lang.Object inOutBuf, int count, Datatype type, Op op)`	Apply the operation given by `op` element-wise to the elements of `inBuf` and `inOutBuf` with the result stored element-wise in `inOutBuf`.
`void`	`reduceScatter(java.lang.Object buf, int[] counts, Datatype type, Op op)`	Combine elements in input buffer of each process using the reduce operation, and scatter the combined values over the output buffers of the processes.
`void`	`reduceScatter(java.lang.Object sendbuf, java.lang.Object recvbuf, int[] recvcounts, Datatype type, Op op)`	Combine elements in input buffer of each process using the reduce operation, and scatter the combined values over the output buffers of the processes.
`void`	`reduceScatterBlock(java.lang.Object buf, int count, Datatype type, Op op)`	Combine values and scatter the results.
`void`	`reduceScatterBlock(java.lang.Object sendbuf, java.lang.Object recvbuf, int recvcount, Datatype type, Op op)`	Combine values and scatter the results.
`void`	`rSend(java.lang.Object buf, int count, Datatype type, int dest, int tag)`	Send in ready mode.
`Prequest`	`rSendInit(java.nio.Buffer buf, int count, Datatype type, int dest, int tag)`	Creates a persistent communication request for a ready mode send.
`void`	`scatter(java.lang.Object buf, int count, Datatype type, int root)`	Inverse of the operation `gather`.
`void`	`scatter(java.lang.Object sendbuf, int sendcount, Datatype sendtype, java.lang.Object recvbuf, int recvcount, Datatype recvtype, int root)`	Inverse of the operation `gather`.
`void`	`scatterv(java.lang.Object sendbuf, int[] sendcount, int[] displs, Datatype sendtype, int root)`	Inverse of the operation `gatherv`.
`void`	`scatterv(java.lang.Object sendbuf, int[] sendcount, int[] displs, Datatype sendtype, java.lang.Object recvbuf, int recvcount, Datatype recvtype, int root)`	Inverse of the operation `gatherv`.
`void`	`scatterv(java.lang.Object recvbuf, int recvcount, Datatype recvtype, int root)`	Inverse of the operation `gatherv`.
`void`	`send(java.lang.Object buf, int count, Datatype type, int dest, int tag)`	Blocking send operation.
`Prequest`	`sendInit(java.nio.Buffer buf, int count, Datatype type, int dest, int tag)`	Creates a persistent communication request for a standard mode send.
`Status`	`sendRecv(java.lang.Object sendbuf, int sendcount, Datatype sendtype, int dest, int sendtag, java.lang.Object recvbuf, int recvcount, Datatype recvtype, int source, int recvtag)`	Execute a blocking send and receive operation.
`Status`	`sendRecvReplace(java.lang.Object buf, int count, Datatype type, int dest, int sendtag, int source, int recvtag)`	Execute a blocking send and receive operation, receiving message into send buffer.
`void`	`setAttr(int keyval, java.lang.Object value)`	Stores attribute value associated with a key.
`void`	`setErrhandler(Errhandler errhandler)`	Associates a new error handler with communicator at the calling process.
`void`	`setInfo(Info info)`	Java binding of `MPI_COMM_SET_INFO`.
`void`	`setName(java.lang.String name)`	Sets the print name for the communicator.
`protected void`	`setType(int type)`
`void`	`sSend(java.lang.Object buf, int count, Datatype type, int dest, int tag)`	Send in synchronous mode.
`Prequest`	`sSendInit(java.nio.Buffer buf, int count, Datatype type, int dest, int tag)`	Creates a persistent communication request for a synchronous mode send.
`int`	`unpack(byte[] inbuf, int position, java.lang.Object outbuf, int outcount, Datatype type)`	Unpacks message in receive buffer `outbuf` into space specified in `inbuf`.

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - TYPE_SHARED
```
public static final int TYPE_SHARED
```
    See Also:
    
    Constant Field Values
  - SELF
```
protected static final int SELF
```
    See Also:
    
    Constant Field Values
  - WORLD
```
protected static final int WORLD
```
    See Also:
    
    Constant Field Values
  - handle
```
protected long handle
```
- Constructor Detail
  - Comm
```
protected Comm()
```
  - Comm
```
protected Comm(long handle)
```
  - Comm
```
protected Comm(long[] commRequest)
```
- Method Detail
  - setType
```
protected final void setType(int type)
```
  - clone
```
public Comm clone()
```
    Duplicates this communicator.
    Java binding of MPI_COMM_DUP.
    It is recommended to use dup() instead of clone() because the last can't throw an MPIException.
    
    Overrides:
    
    clone in class java.lang.Object
    
    Returns:
    
    copy of this communicator
  - dup
```
public Comm dup()
         throws MPIException
```
    Duplicates this communicator.
    Java binding of MPI_COMM_DUP.
    
    Returns:
    
    copy of this communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - dup
```
protected final long dup(long comm)
                  throws MPIException
```
    Throws:
    
    MPIException
  - iDup
```
public Comm iDup()
          throws MPIException
```
    Duplicates this communicator.
    Java binding of MPI_COMM_IDUP.
    The new communicator can't be used before the operation completes. The request object must be obtained calling getRequest().
    
    Returns:
    
    copy of this communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iDup
```
protected final long[] iDup(long comm)
                     throws MPIException
```
    Throws:
    
    MPIException
  - dupWithInfo
```
public Comm dupWithInfo(Info info)
                 throws MPIException
```
    Duplicates this communicator with the info object used in the call.
    Java binding of MPI_COMM_DUP_WITH_INFO.
    
    Parameters:
    
    info - info object to associate with the new communicator
    
    Returns:
    
    copy of this communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - dupWithInfo
```
protected final long dupWithInfo(long comm,
                                 long info)
                          throws MPIException
```
    Throws:
    
    MPIException
  - getRequest
```
public final Request getRequest()
```
    Returns the associated request to this communicator if it was created using iDup().
    
    Returns:
    
    associated request if this communicator was created using iDup(), or null otherwise.
  - getSize
```
public final int getSize()
                  throws MPIException
```
    Size of group of this communicator.
    Java binding of the MPI operation MPI_COMM_SIZE.
    
    Returns:
    
    number of processors in the group of this communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - getRank
```
public final int getRank()
                  throws MPIException
```
    Rank of this process in group of this communicator.
    Java binding of the MPI operation MPI_COMM_RANK.
    
    Returns:
    
    rank of the calling process in the group of this communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - compare
```
public static int compare(Comm comm1,
                          Comm comm2)
                   throws MPIException
```
    Compare two communicators.
    Java binding of the MPI operation MPI_COMM_COMPARE.
    
    Parameters:
    
    comm1 - first communicator
    
    comm2 - second communicator
    
    Returns:
    
    MPI.IDENT results if the comm1 and comm2 are references to the same object (ie, if comm1 == comm2).
    MPI.CONGRUENT results if the underlying groups are identical but the communicators differ by context.
    MPI.SIMILAR results if the underlying groups are similar but the communicators differ by context.
    MPI.UNEQUAL results otherwise.
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - free
```
public final void free()
                throws MPIException
```
    Java binding of the MPI operation MPI_COMM_FREE.
    
    Specified by:
    
    free in interface Freeable
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - isNull
```
public final boolean isNull()
```
    Test if communicator object is null (has been freed). Java binding of MPI_COMM_NULL.
    
    Returns:
    
    true if the comm object is null, false otherwise
  - setInfo
```
public final void setInfo(Info info)
                   throws MPIException
```
    Java binding of MPI_COMM_SET_INFO.
    
    Parameters:
    
    info - info object
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - getInfo
```
public final Info getInfo()
                   throws MPIException
```
    Java binding of MPI_COMM_GET_INFO.
    
    Returns:
    
    new info object
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - disconnect
```
public final void disconnect()
                      throws MPIException
```
    Java binding of the MPI operation MPI_COMM_DISCONNECT.
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - getGroup
```
public final Group getGroup()
                     throws MPIException
```
    Return group associated with a communicator.
    Java binding of the MPI operation MPI_COMM_GROUP.
    
    Returns:
    
    group corresponding to this communicator group
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - isInter
```
public final boolean isInter()
                      throws MPIException
```
    Test if this communicator is an inter-communicator.
    Java binding of the MPI operation MPI_COMM_TEST_INTER.
    
    Returns:
    
    true if this is an inter-communicator, false otherwise
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - createIntercomm
```
public final Intercomm createIntercomm(Comm localComm,
                                       int localLeader,
                                       int remoteLeader,
                                       int tag)
                                throws MPIException
```
    Create an inter-communicator.
    Java binding of the MPI operation MPI_INTERCOMM_CREATE.
    This operation is defined as a method on the "peer communicator", making it analogous to a send or recv communication with the remote group leader.
    
    Parameters:
    
    localComm - local intra-communicator
    
    localLeader - rank of local group leader in localComm
    
    remoteLeader - rank of remote group leader in this communicator
    
    tag - "safe" tag
    
    Returns:
    
    new inter-communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - send
```
public final void send(java.lang.Object buf,
                       int count,
                       Datatype type,
                       int dest,
                       int tag)
                throws MPIException
```
    Blocking send operation.
    Java binding of the MPI operation MPI_SEND.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - recv
```
public final Status recv(java.lang.Object buf,
                         int count,
                         Datatype type,
                         int source,
                         int tag)
                  throws MPIException
```
    Blocking receive operation.
    Java binding of the MPI operation MPI_RECV.
    
    Parameters:
    
    buf - receive buffer
    
    count - number of items in receive buffer
    
    type - datatype of each item in receive buffer
    
    source - rank of source
    
    tag - message tag
    
    Returns:
    
    status object
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - sendRecv
```
public final Status sendRecv(java.lang.Object sendbuf,
                             int sendcount,
                             Datatype sendtype,
                             int dest,
                             int sendtag,
                             java.lang.Object recvbuf,
                             int recvcount,
                             Datatype recvtype,
                             int source,
                             int recvtag)
                      throws MPIException
```
    Execute a blocking send and receive operation.
    Java binding of the MPI operation MPI_SENDRECV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    dest - rank of destination
    
    sendtag - send tag
    
    recvbuf - receive buffer
    
    recvcount - number of items in receive buffer
    
    recvtype - datatype of each item in receive buffer
    
    source - rank of source
    
    recvtag - receive tag
    
    Returns:
    
    status object
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int), recv(Object, int, Datatype, int, int)
  - sendRecvReplace
```
public final Status sendRecvReplace(java.lang.Object buf,
                                    int count,
                                    Datatype type,
                                    int dest,
                                    int sendtag,
                                    int source,
                                    int recvtag)
                             throws MPIException
```
    Execute a blocking send and receive operation, receiving message into send buffer.
    Java binding of the MPI operation MPI_SENDRECV_REPLACE.
    
    Parameters:
    
    buf - buffer
    
    count - number of items to send
    
    type - datatype of each item in buffer
    
    dest - rank of destination
    
    sendtag - send tag
    
    source - rank of source
    
    recvtag - receive tag
    
    Returns:
    
    status object
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int), recv(Object, int, Datatype, int, int)
  - bSend
```
public final void bSend(java.lang.Object buf,
                        int count,
                        Datatype type,
                        int dest,
                        int tag)
                 throws MPIException
```
    Send in buffered mode.
    Java binding of the MPI operation MPI_BSEND.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - sSend
```
public final void sSend(java.lang.Object buf,
                        int count,
                        Datatype type,
                        int dest,
                        int tag)
                 throws MPIException
```
    Send in synchronous mode.
    Java binding of the MPI operation MPI_SSEND.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - rSend
```
public final void rSend(java.lang.Object buf,
                        int count,
                        Datatype type,
                        int dest,
                        int tag)
                 throws MPIException
```
    Send in ready mode.
    Java binding of the MPI operation MPI_RSEND.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - iSend
```
public final Request iSend(java.nio.Buffer buf,
                           int count,
                           Datatype type,
                           int dest,
                           int tag)
                    throws MPIException
```
    Start a standard mode, nonblocking send.
    Java binding of the MPI operation MPI_ISEND.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - ibSend
```
public final Request ibSend(java.nio.Buffer buf,
                            int count,
                            Datatype type,
                            int dest,
                            int tag)
                     throws MPIException
```
    Start a buffered mode, nonblocking send.
    Java binding of the MPI operation MPI_IBSEND.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - isSend
```
public final Request isSend(java.nio.Buffer buf,
                            int count,
                            Datatype type,
                            int dest,
                            int tag)
                     throws MPIException
```
    Start a synchronous mode, nonblocking send.
    Java binding of the MPI operation MPI_ISSEND.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - irSend
```
public final Request irSend(java.nio.Buffer buf,
                            int count,
                            Datatype type,
                            int dest,
                            int tag)
                     throws MPIException
```
    Start a ready mode, nonblocking send.
    Java binding of the MPI operation MPI_IRSEND.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - iRecv
```
public final Request iRecv(java.nio.Buffer buf,
                           int count,
                           Datatype type,
                           int source,
                           int tag)
                    throws MPIException
```
    Start a nonblocking receive.
    Java binding of the MPI operation MPI_IRECV.
    
    Parameters:
    
    buf - receive buffer
    
    count - number of items in receive buffer
    
    type - datatype of each item in receive buffer
    
    source - rank of source
    
    tag - message tag
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    recv(Object, int, Datatype, int, int)
  - sendInit
```
public final Prequest sendInit(java.nio.Buffer buf,
                               int count,
                               Datatype type,
                               int dest,
                               int tag)
                        throws MPIException
```
    Creates a persistent communication request for a standard mode send.
    Java binding of the MPI operation MPI_SEND_INIT.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Returns:
    
    persistent communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - bSendInit
```
public final Prequest bSendInit(java.nio.Buffer buf,
                                int count,
                                Datatype type,
                                int dest,
                                int tag)
                         throws MPIException
```
    Creates a persistent communication request for a buffered mode send.
    Java binding of the MPI operation MPI_BSEND_INIT.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Returns:
    
    persistent communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - sSendInit
```
public final Prequest sSendInit(java.nio.Buffer buf,
                                int count,
                                Datatype type,
                                int dest,
                                int tag)
                         throws MPIException
```
    Creates a persistent communication request for a synchronous mode send.
    Java binding of the MPI operation MPI_SSEND_INIT.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Returns:
    
    persistent communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - rSendInit
```
public final Prequest rSendInit(java.nio.Buffer buf,
                                int count,
                                Datatype type,
                                int dest,
                                int tag)
                         throws MPIException
```
    Creates a persistent communication request for a ready mode send.
    Java binding of the MPI operation MPI_RSEND_INIT.
    
    Parameters:
    
    buf - send buffer
    
    count - number of items to send
    
    type - datatype of each item in send buffer
    
    dest - rank of destination
    
    tag - message tag
    
    Returns:
    
    persistent communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    send(Object, int, Datatype, int, int)
  - recvInit
```
public final Prequest recvInit(java.nio.Buffer buf,
                               int count,
                               Datatype type,
                               int source,
                               int tag)
                        throws MPIException
```
    Creates a persistent communication request for a receive operation.
    Java binding of the MPI operation MPI_RECV_INIT.
    
    Parameters:
    
    buf - receive buffer
    
    count - number of items in receive buffer
    
    type - datatype of each item in receive buffer
    
    source - rank of source
    
    tag - message tag
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
    
    See Also:
    
    recv(Object, int, Datatype, int, int)
  - pack
```
public final int pack(java.lang.Object inbuf,
                      int incount,
                      Datatype type,
                      byte[] outbuf,
                      int position)
               throws MPIException
```
    Packs message in send buffer inbuf into space specified in outbuf.
    Java binding of the MPI operation MPI_PACK.
    The return value is the output value of position - the inital value incremented by the number of bytes written.
    
    Parameters:
    
    inbuf - input buffer
    
    incount - number of items in input buffer
    
    type - datatype of each item in input buffer
    
    outbuf - output buffer
    
    position - initial position in output buffer
    
    Returns:
    
    final position in output buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - unpack
```
public final int unpack(byte[] inbuf,
                        int position,
                        java.lang.Object outbuf,
                        int outcount,
                        Datatype type)
                 throws MPIException
```
    Unpacks message in receive buffer outbuf into space specified in inbuf.
    Java binding of the MPI operation MPI_UNPACK.
    The return value is the output value of position - the inital value incremented by the number of bytes read.
    
    Parameters:
    
    inbuf - input buffer
    
    position - initial position in input buffer
    
    outbuf - output buffer
    
    outcount - number of items in output buffer
    
    type - datatype of each item in output buffer
    
    Returns:
    
    final position in input buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - packSize
```
public final int packSize(int incount,
                          Datatype type)
                   throws MPIException
```
    Returns an upper bound on the increment of position effected by pack.
    Java binding of the MPI operation MPI_PACK_SIZE.
    
    Parameters:
    
    incount - number of items in input buffer
    
    type - datatype of each item in input buffer
    
    Returns:
    
    upper bound on size of packed message
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iProbe
```
public final Status iProbe(int source,
                           int tag)
                    throws MPIException
```
    Check if there is an incoming message matching the pattern specified.
    Java binding of the MPI operation MPI_IPROBE.
    If such a message is currently available, a status object similar to the return value of a matching recv operation is returned.
    
    Parameters:
    
    source - rank of source
    
    tag - message tag
    
    Returns:
    
    status object if such a message is currently available, null otherwise.
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - probe
```
public final Status probe(int source,
                          int tag)
                   throws MPIException
```
    Wait until there is an incoming message matching the pattern specified.
    Java binding of the MPI operation MPI_PROBE.
    Returns a status object similar to the return value of a matching recv operation.
    
    Parameters:
    
    source - rank of source
    
    tag - message tag
    
    Returns:
    
    status object
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - createKeyval
```
public static int createKeyval()
                        throws MPIException
```
    Create a new attribute key.
    Java binding of the MPI operation MPI_COMM_CREATE_KEYVAL.
    
    Returns:
    
    attribute key for future access
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - freeKeyval
```
public static void freeKeyval(int keyval)
                       throws MPIException
```
    Frees an attribute key for communicators.
    Java binding of the MPI operation MPI_COMM_FREE_KEYVAL.
    
    Parameters:
    
    keyval - attribute key
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - setAttr
```
public final void setAttr(int keyval,
                          java.lang.Object value)
                   throws MPIException
```
    Stores attribute value associated with a key.
    Java binding of the MPI operation MPI_COMM_SET_ATTR.
    
    Parameters:
    
    keyval - attribute key
    
    value - attribute value
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - getAttr
```
public final java.lang.Object getAttr(int keyval)
                               throws MPIException
```
    Retrieves attribute value by key.
    Java binding of the MPI operation MPI_COMM_GET_ATTR.
    
    Parameters:
    
    keyval - attribute key
    
    Returns:
    
    attribute value or null if no attribute is associated with the key.
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - deleteAttr
```
public final void deleteAttr(int keyval)
                      throws MPIException
```
    Deletes an attribute value associated with a key on a communicator.
    Java binding of the MPI operation MPI_COMM_DELETE_ATTR.
    
    Parameters:
    
    keyval - attribute key
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - getTopology
```
public final int getTopology()
                      throws MPIException
```
    Returns the type of topology associated with the communicator.
    Java binding of the MPI operation MPI_TOPO_TEST.
    The return value will be one of MPI.GRAPH, MPI.CART, MPI.DIST_GRAPH or MPI.UNDEFINED.
    
    Returns:
    
    topology type of communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - abort
```
public final void abort(int errorcode)
                 throws MPIException
```
    Abort MPI.
    Java binding of the MPI operation MPI_ABORT.
    
    Parameters:
    
    errorcode - error code for Unix or POSIX environments
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - setErrhandler
```
public final void setErrhandler(Errhandler errhandler)
                         throws MPIException
```
    Associates a new error handler with communicator at the calling process.
    Java binding of the MPI operation MPI_COMM_SET_ERRHANDLER.
    
    Parameters:
    
    errhandler - new MPI error handler for communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - getErrhandler
```
public final Errhandler getErrhandler()
                               throws MPIException
```
    Returns the error handler currently associated with the communicator.
    Java binding of the MPI operation MPI_COMM_GET_ERRHANDLER.
    
    Returns:
    
    MPI error handler currently associated with communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - callErrhandler
```
public void callErrhandler(int errorCode)
                    throws MPIException
```
    Calls the error handler currently associated with the communicator.
    Java binding of the MPI operation MPI_COMM_CALL_ERRHANDLER.
    
    Parameters:
    
    errorCode - error code
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - barrier
```
public final void barrier()
                   throws MPIException
```
    A call to barrier blocks the caller until all process in the group have called it.
    Java binding of the MPI operation MPI_BARRIER.
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iBarrier
```
public final Request iBarrier()
                       throws MPIException
```
    Nonblocking barrier synchronization.
    Java binding of the MPI operation MPI_IBARRIER.
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - bcast
```
public final void bcast(java.lang.Object buf,
                        int count,
                        Datatype type,
                        int root)
                 throws MPIException
```
    Broadcast a message from the process with rank root to all processes of the group.
    Java binding of the MPI operation MPI_BCAST.
    
    Parameters:
    
    buf - buffer
    
    count - number of items in buffer
    
    type - datatype of each item in buffer
    
    root - rank of broadcast root
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iBcast
```
public final Request iBcast(java.nio.Buffer buf,
                            int count,
                            Datatype type,
                            int root)
                     throws MPIException
```
    Broadcast a message from the process with rank root to all processes of the group.
    Java binding of the MPI operation MPI_IBCAST.
    
    Parameters:
    
    buf - buffer
    
    count - number of items in buffer
    
    type - datatype of each item in buffer
    
    root - rank of broadcast root
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - gather
```
public final void gather(java.lang.Object sendbuf,
                         int sendcount,
                         Datatype sendtype,
                         java.lang.Object recvbuf,
                         int recvcount,
                         Datatype recvtype,
                         int root)
                  throws MPIException
```
    Each process sends the contents of its send buffer to the root process.
    Java binding of the MPI operation MPI_GATHER.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of receiving process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - gather
```
public final void gather(java.lang.Object buf,
                         int count,
                         Datatype type,
                         int root)
                  throws MPIException
```
    Each process sends the contents of its send buffer to the root process.
    Java binding of the MPI operation MPI_GATHER using MPI_IN_PLACE instead of the send buffer. The buffer is used by the root process to receive data, and it is used by the non-root processes to send data.
    
    Parameters:
    
    buf - buffer
    
    count - number of items to send/receive
    
    type - datatype of each item in buffer
    
    root - rank of receiving process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iGather
```
public final Request iGather(java.nio.Buffer sendbuf,
                             int sendcount,
                             Datatype sendtype,
                             java.nio.Buffer recvbuf,
                             int recvcount,
                             Datatype recvtype,
                             int root)
                      throws MPIException
```
    Each process sends the contents of its send buffer to the root process.
    Java binding of the MPI operation MPI_IGATHER.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of receiving process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iGather
```
public final Request iGather(java.nio.Buffer buf,
                             int count,
                             Datatype type,
                             int root)
                      throws MPIException
```
    Each process sends the contents of its send buffer to the root process.
    Java binding of the MPI operation MPI_IGATHER using MPI_IN_PLACE instead of the send buffer. The buffer is used by the root process to receive data, and it is used by the non-root processes to send data.
    
    Parameters:
    
    buf - buffer
    
    count - number of items to send/receive
    
    type - datatype of each item in buffer
    
    root - rank of receiving process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - gatherv
```
public final void gatherv(java.lang.Object sendbuf,
                          int sendcount,
                          Datatype sendtype,
                          java.lang.Object recvbuf,
                          int[] recvcount,
                          int[] displs,
                          Datatype recvtype,
                          int root)
                   throws MPIException
```
    Extends functionality of gather by allowing varying counts of data from each process.
    Java binding of the MPI operation MPI_GATHERV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of receiving process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - gatherv
```
public final void gatherv(java.lang.Object recvbuf,
                          int[] recvcount,
                          int[] displs,
                          Datatype recvtype,
                          int root)
                   throws MPIException
```
    Extends functionality of gather by allowing varying counts of data from each process.
    Java binding of the MPI operation MPI_GATHERV using MPI_IN_PLACE instead of the send buffer in the root process. This method must be used in the root process.
    
    Parameters:
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of receiving process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - gatherv
```
public final void gatherv(java.lang.Object sendbuf,
                          int sendcount,
                          Datatype sendtype,
                          int root)
                   throws MPIException
```
    Extends functionality of gather by allowing varying counts of data from each process.
    Java binding of the MPI operation MPI_GATHERV using MPI_IN_PLACE instead of the send buffer in the root process. This method must be used in the non-root processes.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    root - rank of receiving process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iGatherv
```
public final Request iGatherv(java.nio.Buffer sendbuf,
                              int sendcount,
                              Datatype sendtype,
                              java.nio.Buffer recvbuf,
                              int[] recvcount,
                              int[] displs,
                              Datatype recvtype,
                              int root)
                       throws MPIException
```
    Extends functionality of gather by allowing varying counts of data from each process.
    Java binding of the MPI operation MPI_IGATHERV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of receiving process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iGatherv
```
public final Request iGatherv(java.nio.Buffer recvbuf,
                              int[] recvcount,
                              int[] displs,
                              Datatype recvtype,
                              int root)
                       throws MPIException
```
    Extends functionality of gather by allowing varying counts of data from each process.
    Java binding of the MPI operation MPI_IGATHERV using MPI_IN_PLACE instead of the send buffer in the root process. This method must be used in the root process.
    
    Parameters:
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of receiving process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iGatherv
```
public final Request iGatherv(java.nio.Buffer sendbuf,
                              int sendcount,
                              Datatype sendtype,
                              int root)
                       throws MPIException
```
    Extends functionality of gather by allowing varying counts of data from each process.
    Java binding of the MPI operation MPI_IGATHERV using MPI_IN_PLACE instead of the send buffer in the root process. This method must be used in the non-root processes.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    root - rank of receiving process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - scatter
```
public final void scatter(java.lang.Object sendbuf,
                          int sendcount,
                          Datatype sendtype,
                          java.lang.Object recvbuf,
                          int recvcount,
                          Datatype recvtype,
                          int root)
                   throws MPIException
```
    Inverse of the operation gather.
    Java binding of the MPI operation MPI_SCATTER.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of sending process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - scatter
```
public final void scatter(java.lang.Object buf,
                          int count,
                          Datatype type,
                          int root)
                   throws MPIException
```
    Inverse of the operation gather.
    Java binding of the MPI operation MPI_SCATTER using MPI_IN_PLACE instead of the receive buffer. The buffer is used by the root process to send data, and it is used by the non-root processes to receive data.
    
    Parameters:
    
    buf - send/receive buffer
    
    count - number of items to send/receive
    
    type - datatype of each item in buffer
    
    root - rank of sending process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iScatter
```
public final Request iScatter(java.nio.Buffer sendbuf,
                              int sendcount,
                              Datatype sendtype,
                              java.nio.Buffer recvbuf,
                              int recvcount,
                              Datatype recvtype,
                              int root)
                       throws MPIException
```
    Inverse of the operation gather.
    Java binding of the MPI operation MPI_ISCATTER.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of sending process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iScatter
```
public final Request iScatter(java.nio.Buffer buf,
                              int count,
                              Datatype type,
                              int root)
                       throws MPIException
```
    Inverse of the operation gather.
    Java binding of the MPI operation MPI_ISCATTER using MPI_IN_PLACE instead of the receive buffer. The buffer is used by the root process to send data, and it is used by the non-root processes to receive data.
    
    Parameters:
    
    buf - send/receive buffer
    
    count - number of items to send/receive
    
    type - datatype of each item in buffer
    
    root - rank of sending process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - scatterv
```
public final void scatterv(java.lang.Object sendbuf,
                           int[] sendcount,
                           int[] displs,
                           Datatype sendtype,
                           java.lang.Object recvbuf,
                           int recvcount,
                           Datatype recvtype,
                           int root)
                    throws MPIException
```
    Inverse of the operation gatherv.
    Java binding of the MPI operation MPI_SCATTERV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each process
    
    displs - displacements from which to take outgoing data
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of sending process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - scatterv
```
public final void scatterv(java.lang.Object sendbuf,
                           int[] sendcount,
                           int[] displs,
                           Datatype sendtype,
                           int root)
                    throws MPIException
```
    Inverse of the operation gatherv.
    Java binding of the MPI operation MPI_SCATTERV using MPI_IN_PLACE instead of the receive buffer in the root process. This method must be used in the root process.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each process
    
    displs - displacements from which to take outgoing data
    
    sendtype - datatype of each item in send buffer
    
    root - rank of sending process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - scatterv
```
public final void scatterv(java.lang.Object recvbuf,
                           int recvcount,
                           Datatype recvtype,
                           int root)
                    throws MPIException
```
    Inverse of the operation gatherv.
    Java binding of the MPI operation MPI_SCATTERV using MPI_IN_PLACE instead of the receive buffer in the root process. This method must be used in the non-root processes.
    
    Parameters:
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of sending process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iScatterv
```
public final Request iScatterv(java.nio.Buffer sendbuf,
                               int[] sendcount,
                               int[] displs,
                               Datatype sendtype,
                               java.nio.Buffer recvbuf,
                               int recvcount,
                               Datatype recvtype,
                               int root)
                        throws MPIException
```
    Inverse of the operation gatherv.
    Java binding of the MPI operation MPI_ISCATTERV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each process
    
    displs - displacements from which to take outgoing data
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of sending process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iScatterv
```
public final Request iScatterv(java.nio.Buffer sendbuf,
                               int[] sendcount,
                               int[] displs,
                               Datatype sendtype,
                               int root)
                        throws MPIException
```
    Inverse of the operation gatherv.
    Java binding of the MPI operation MPI_ISCATTERV using MPI_IN_PLACE instead of the receive buffer in the root process. This method must be used in the root process.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each process
    
    displs - displacements from which to take outgoing data
    
    sendtype - datatype of each item in send buffer
    
    root - rank of sending process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iScatterv
```
public final Request iScatterv(java.nio.Buffer recvbuf,
                               int recvcount,
                               Datatype recvtype,
                               int root)
                        throws MPIException
```
    Inverse of the operation gatherv.
    Java binding of the MPI operation MPI_ISCATTERV using MPI_IN_PLACE instead of the receive buffer in the root process. This method must be used in the non-root processes.
    
    Parameters:
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    root - rank of sending process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allGather
```
public final void allGather(java.lang.Object sendbuf,
                            int sendcount,
                            Datatype sendtype,
                            java.lang.Object recvbuf,
                            int recvcount,
                            Datatype recvtype)
                     throws MPIException
```
    Similar to gather, but all processes receive the result.
    Java binding of the MPI operation MPI_ALLGATHER.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allGather
```
public final void allGather(java.lang.Object buf,
                            int count,
                            Datatype type)
                     throws MPIException
```
    Similar to gather, but all processes receive the result.
    Java binding of the MPI operation MPI_ALLGATHER using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    count - number of items to receive
    
    type - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllGather
```
public final Request iAllGather(java.nio.Buffer sendbuf,
                                int sendcount,
                                Datatype sendtype,
                                java.nio.Buffer recvbuf,
                                int recvcount,
                                Datatype recvtype)
                         throws MPIException
```
    Similar to gather, but all processes receive the result.
    Java binding of the MPI operation MPI_IALLGATHER.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllGather
```
public final Request iAllGather(java.nio.Buffer buf,
                                int count,
                                Datatype type)
                         throws MPIException
```
    Similar to gather, but all processes receive the result.
    Java binding of the MPI operation MPI_IALLGATHER using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    count - number of items to receive
    
    type - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allGatherv
```
public final void allGatherv(java.lang.Object sendbuf,
                             int sendcount,
                             Datatype sendtype,
                             java.lang.Object recvbuf,
                             int[] recvcount,
                             int[] displs,
                             Datatype recvtype)
                      throws MPIException
```
    Similar to gatherv, but all processes receive the result.
    Java binding of the MPI operation MPI_ALLGATHERV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allGatherv
```
public final void allGatherv(java.lang.Object recvbuf,
                             int[] recvcount,
                             int[] displs,
                             Datatype recvtype)
                      throws MPIException
```
    Similar to gatherv, but all processes receive the result.
    Java binding of the MPI operation MPI_ALLGATHERV using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllGatherv
```
public final Request iAllGatherv(java.nio.Buffer sendbuf,
                                 int sendcount,
                                 Datatype sendtype,
                                 java.nio.Buffer recvbuf,
                                 int[] recvcount,
                                 int[] displs,
                                 Datatype recvtype)
                          throws MPIException
```
    Similar to gatherv, but all processes receive the result.
    Java binding of the MPI operation MPI_IALLGATHERV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllGatherv
```
public final Request iAllGatherv(java.nio.Buffer buf,
                                 int[] count,
                                 int[] displs,
                                 Datatype type)
                          throws MPIException
```
    Similar to gatherv, but all processes receive the result.
    Java binding of the MPI operation MPI_IALLGATHERV using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    count - number of elements received from each process
    
    displs - displacements at which to place incoming data
    
    type - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allToAll
```
public final void allToAll(java.lang.Object sendbuf,
                           int sendcount,
                           Datatype sendtype,
                           java.lang.Object recvbuf,
                           int recvcount,
                           Datatype recvtype)
                    throws MPIException
```
    Extension of allGather to the case where each process sends distinct data to each of the receivers.
    Java binding of the MPI operation MPI_ALLTOALL.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each process
    
    sendtype - datatype send buffer items
    
    recvbuf - receive buffer
    
    recvcount - number of items received from any process
    
    recvtype - datatype of receive buffer items
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllToAll
```
public final Request iAllToAll(java.nio.Buffer sendbuf,
                               int sendcount,
                               Datatype sendtype,
                               java.nio.Buffer recvbuf,
                               int recvcount,
                               Datatype recvtype)
                        throws MPIException
```
    Extension of allGather to the case where each process sends distinct data to each of the receivers.
    Java binding of the MPI operation MPI_IALLTOALL.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each process
    
    sendtype - datatype send buffer items
    
    recvbuf - receive buffer
    
    recvcount - number of items received from any process
    
    recvtype - datatype of receive buffer items
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allToAllv
```
public final void allToAllv(java.lang.Object sendbuf,
                            int[] sendcount,
                            int[] sdispls,
                            Datatype sendtype,
                            java.lang.Object recvbuf,
                            int[] recvcount,
                            int[] rdispls,
                            Datatype recvtype)
                     throws MPIException
```
    Adds flexibility to allToAll: location of data for send is specified by sdispls and location to place data on receive side is specified by rdispls.
    Java binding of the MPI operation MPI_ALLTOALLV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each buffer
    
    sdispls - displacements from which to take outgoing data
    
    sendtype - datatype send buffer items
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    rdispls - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllToAllv
```
public final Request iAllToAllv(java.nio.Buffer sendbuf,
                                int[] sendcount,
                                int[] sdispls,
                                Datatype sendtype,
                                java.nio.Buffer recvbuf,
                                int[] recvcount,
                                int[] rdispls,
                                Datatype recvtype)
                         throws MPIException
```
    Adds flexibility to allToAll: location of data for send is specified by sdispls and location to place data on receive side is specified by rdispls.
    Java binding of the MPI operation MPI_IALLTOALLV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each buffer
    
    sdispls - displacements from which to take outgoing data
    
    sendtype - datatype send buffer items
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    rdispls - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allToAllw
```
public final void allToAllw(java.lang.Object sendBuf,
                            int[] sendCount,
                            int[] sDispls,
                            Datatype[] sendTypes,
                            java.lang.Object recvBuf,
                            int[] recvCount,
                            int[] rDispls,
                            Datatype[] recvTypes)
                     throws MPIException
```
    Adds more flexibility to allToAllv: datatypes for send are specified by sendTypes and datatypes for receive are specified by recvTypes per process.
    Java binding of the MPI operation MPI_ALLTOALLW.
    
    Parameters:
    
    sendBuf - send buffer
    
    sendCount - number of items sent to each buffer
    
    sDispls - displacements from which to take outgoing data
    
    sendTypes - datatypes of send buffer items
    
    recvBuf - receive buffer
    
    recvCount - number of elements received from each process
    
    rDispls - displacements at which to place incoming data
    
    recvTypes - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllToAllw
```
public final Request iAllToAllw(java.nio.Buffer sendBuf,
                                int[] sendCount,
                                int[] sDispls,
                                Datatype[] sendTypes,
                                java.nio.Buffer recvBuf,
                                int[] recvCount,
                                int[] rDispls,
                                Datatype[] recvTypes)
                         throws MPIException
```
    Adds more flexibility to iAllToAllv: datatypes for send are specified by sendTypes and datatypes for receive are specified by recvTypes per process.
    Java binding of the MPI operation MPI_IALLTOALLW.
    
    Parameters:
    
    sendBuf - send buffer
    
    sendCount - number of items sent to each buffer
    
    sDispls - displacements from which to take outgoing data
    
    sendTypes - datatype send buffer items
    
    recvBuf - receive buffer
    
    recvCount - number of elements received from each process
    
    rDispls - displacements at which to place incoming data
    
    recvTypes - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - neighborAllGather
```
public final void neighborAllGather(java.lang.Object sendbuf,
                                    int sendcount,
                                    Datatype sendtype,
                                    java.lang.Object recvbuf,
                                    int recvcount,
                                    Datatype recvtype)
                             throws MPIException
```
    Java binding of MPI_NEIGHBOR_ALLGATHER.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iNeighborAllGather
```
public final Request iNeighborAllGather(java.nio.Buffer sendbuf,
                                        int sendcount,
                                        Datatype sendtype,
                                        java.nio.Buffer recvbuf,
                                        int recvcount,
                                        Datatype recvtype)
                                 throws MPIException
```
    Java binding of MPI_INEIGHBOR_ALLGATHER.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - neighborAllGatherv
```
public final void neighborAllGatherv(java.lang.Object sendbuf,
                                     int sendcount,
                                     Datatype sendtype,
                                     java.lang.Object recvbuf,
                                     int[] recvcount,
                                     int[] displs,
                                     Datatype recvtype)
                              throws MPIException
```
    Java binding of MPI_NEIGHBOR_ALLGATHERV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of elements that are received from each neighbor
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of receive buffer elements
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iNeighborAllGatherv
```
public final Request iNeighborAllGatherv(java.nio.Buffer sendbuf,
                                         int sendcount,
                                         Datatype sendtype,
                                         java.nio.Buffer recvbuf,
                                         int[] recvcount,
                                         int[] displs,
                                         Datatype recvtype)
                                  throws MPIException
```
    Java binding of MPI_INEIGHBOR_ALLGATHERV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of elements that are received from each neighbor
    
    displs - displacements at which to place incoming data
    
    recvtype - datatype of receive buffer elements
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - neighborAllToAll
```
public final void neighborAllToAll(java.lang.Object sendbuf,
                                   int sendcount,
                                   Datatype sendtype,
                                   java.lang.Object recvbuf,
                                   int recvcount,
                                   Datatype recvtype)
                            throws MPIException
```
    Java binding of MPI_NEIGHBOR_ALLTOALL.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iNeighborAllToAll
```
public final Request iNeighborAllToAll(java.nio.Buffer sendbuf,
                                       int sendcount,
                                       Datatype sendtype,
                                       java.nio.Buffer recvbuf,
                                       int recvcount,
                                       Datatype recvtype)
                                throws MPIException
```
    Java binding of MPI_INEIGHBOR_ALLTOALL.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items to send
    
    sendtype - datatype of each item in send buffer
    
    recvbuf - receive buffer
    
    recvcount - number of items to receive
    
    recvtype - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - neighborAllToAllv
```
public final void neighborAllToAllv(java.lang.Object sendbuf,
                                    int[] sendcount,
                                    int[] sdispls,
                                    Datatype sendtype,
                                    java.lang.Object recvbuf,
                                    int[] recvcount,
                                    int[] rdispls,
                                    Datatype recvtype)
                             throws MPIException
```
    Java binding of MPI_NEIGHBOR_ALLTOALLV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each buffer
    
    sdispls - displacements from which to take outgoing data
    
    sendtype - datatype send buffer items
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    rdispls - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iNeighborAllToAllv
```
public final Request iNeighborAllToAllv(java.nio.Buffer sendbuf,
                                        int[] sendcount,
                                        int[] sdispls,
                                        Datatype sendtype,
                                        java.nio.Buffer recvbuf,
                                        int[] recvcount,
                                        int[] rdispls,
                                        Datatype recvtype)
                                 throws MPIException
```
    Java binding of MPI_INEIGHBOR_ALLTOALLV.
    
    Parameters:
    
    sendbuf - send buffer
    
    sendcount - number of items sent to each buffer
    
    sdispls - displacements from which to take outgoing data
    
    sendtype - datatype send buffer items
    
    recvbuf - receive buffer
    
    recvcount - number of elements received from each process
    
    rdispls - displacements at which to place incoming data
    
    recvtype - datatype of each item in receive buffer
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - reduce
```
public final void reduce(java.lang.Object sendbuf,
                         java.lang.Object recvbuf,
                         int count,
                         Datatype type,
                         Op op,
                         int root)
                  throws MPIException
```
    Combine elements in input buffer of each process using the reduce operation, and return the combined value in the output buffer of the root process.
    Java binding of the MPI operation MPI_REDUCE.
    The predefined operations are available in Java as MPI.MAX, MPI.MIN, MPI.SUM, MPI.PROD, MPI.LAND, MPI.BAND, MPI.LOR, MPI.BOR, MPI.LXOR, MPI.BXOR, MPI.MINLOC and MPI.MAXLOC.
    
    Parameters:
    
    sendbuf - send buffer
    
    recvbuf - receive buffer
    
    count - number of items in send buffer
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    root - rank of root process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - reduce
```
public final void reduce(java.lang.Object buf,
                         int count,
                         Datatype type,
                         Op op,
                         int root)
                  throws MPIException
```
    Combine elements in input buffer of each process using the reduce operation, and return the combined value in the output buffer of the root process.
    Java binding of the MPI operation MPI_REDUCE using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - send/receive buffer
    
    count - number of items in buffer
    
    type - data type of each item in buffer
    
    op - reduce operation
    
    root - rank of root process
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iReduce
```
public final Request iReduce(java.nio.Buffer sendbuf,
                             java.nio.Buffer recvbuf,
                             int count,
                             Datatype type,
                             Op op,
                             int root)
                      throws MPIException
```
    Combine elements in input buffer of each process using the reduce operation, and return the combined value in the output buffer of the root process.
    Java binding of the MPI operation MPI_IREDUCE.
    
    Parameters:
    
    sendbuf - send buffer
    
    recvbuf - receive buffer
    
    count - number of items in send buffer
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    root - rank of root process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iReduce
```
public final Request iReduce(java.nio.Buffer buf,
                             int count,
                             Datatype type,
                             Op op,
                             int root)
                      throws MPIException
```
    Combine elements in input buffer of each process using the reduce operation, and return the combined value in the output buffer of the root process.
    Java binding of the MPI operation MPI_IREDUCE using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - send/receive buffer
    
    count - number of items in buffer
    
    type - data type of each item in buffer
    
    op - reduce operation
    
    root - rank of root process
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allReduce
```
public final void allReduce(java.lang.Object sendbuf,
                            java.lang.Object recvbuf,
                            int count,
                            Datatype type,
                            Op op)
                     throws MPIException
```
    Same as reduce except that the result appears in receive buffer of all process in the group.
    Java binding of the MPI operation MPI_ALLREDUCE.
    
    Parameters:
    
    sendbuf - send buffer
    
    recvbuf - receive buffer
    
    count - number of items in send buffer
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - allReduce
```
public final void allReduce(java.lang.Object buf,
                            int count,
                            Datatype type,
                            Op op)
                     throws MPIException
```
    Same as reduce except that the result appears in receive buffer of all process in the group.
    Java binding of the MPI operation MPI_ALLREDUCE using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    count - number of items in send buffer
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllReduce
```
public final Request iAllReduce(java.nio.Buffer sendbuf,
                                java.nio.Buffer recvbuf,
                                int count,
                                Datatype type,
                                Op op)
                         throws MPIException
```
    Same as reduce except that the result appears in receive buffer of all process in the group.
    Java binding of the MPI operation MPI_IALLREDUCE.
    
    Parameters:
    
    sendbuf - send buffer
    
    recvbuf - receive buffer
    
    count - number of items in send buffer
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iAllReduce
```
public final Request iAllReduce(java.nio.Buffer buf,
                                int count,
                                Datatype type,
                                Op op)
                         throws MPIException
```
    Same as reduce except that the result appears in receive buffer of all process in the group.
    Java binding of the MPI operation MPI_IALLREDUCE using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    count - number of items in send buffer
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - reduceScatter
```
public final void reduceScatter(java.lang.Object sendbuf,
                                java.lang.Object recvbuf,
                                int[] recvcounts,
                                Datatype type,
                                Op op)
                         throws MPIException
```
    Combine elements in input buffer of each process using the reduce operation, and scatter the combined values over the output buffers of the processes.
    Java binding of the MPI operation MPI_REDUCE_SCATTER.
    
    Parameters:
    
    sendbuf - send buffer
    
    recvbuf - receive buffer
    
    recvcounts - numbers of result elements distributed to each process
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - reduceScatter
```
public final void reduceScatter(java.lang.Object buf,
                                int[] counts,
                                Datatype type,
                                Op op)
                         throws MPIException
```
    Combine elements in input buffer of each process using the reduce operation, and scatter the combined values over the output buffers of the processes.
    Java binding of the MPI operation MPI_REDUCE_SCATTER using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    counts - numbers of result elements distributed to each process
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iReduceScatter
```
public final Request iReduceScatter(java.nio.Buffer sendbuf,
                                    java.nio.Buffer recvbuf,
                                    int[] recvcounts,
                                    Datatype type,
                                    Op op)
                             throws MPIException
```
    Combine elements in input buffer of each process using the reduce operation, and scatter the combined values over the output buffers of the processes.
    Java binding of the MPI operation MPI_IREDUCE_SCATTER.
    
    Parameters:
    
    sendbuf - send buffer
    
    recvbuf - receive buffer
    
    recvcounts - numbers of result elements distributed to each process
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iReduceScatter
```
public final Request iReduceScatter(java.nio.Buffer buf,
                                    int[] counts,
                                    Datatype type,
                                    Op op)
                             throws MPIException
```
    Combine elements in input buffer of each process using the reduce operation, and scatter the combined values over the output buffers of the processes.
    Java binding of the MPI operation MPI_IREDUCE_SCATTER using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    counts - numbers of result elements distributed to each process
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - reduceScatterBlock
```
public final void reduceScatterBlock(java.lang.Object sendbuf,
                                     java.lang.Object recvbuf,
                                     int recvcount,
                                     Datatype type,
                                     Op op)
                              throws MPIException
```
    Combine values and scatter the results.
    Java binding of the MPI operation MPI_REDUCE_SCATTER_BLOCK.
    
    Parameters:
    
    sendbuf - send buffer
    
    recvbuf - receive buffer
    
    recvcount - element count per block
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - reduceScatterBlock
```
public final void reduceScatterBlock(java.lang.Object buf,
                                     int count,
                                     Datatype type,
                                     Op op)
                              throws MPIException
```
    Combine values and scatter the results.
    Java binding of the MPI operation MPI_REDUCE_SCATTER_BLOCK using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    count - element count per block
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iReduceScatterBlock
```
public final Request iReduceScatterBlock(java.nio.Buffer sendbuf,
                                         java.nio.Buffer recvbuf,
                                         int recvcount,
                                         Datatype type,
                                         Op op)
                                  throws MPIException
```
    Combine values and scatter the results.
    Java binding of the MPI operation MPI_IREDUCE_SCATTER_BLOCK.
    
    Parameters:
    
    sendbuf - send buffer
    
    recvbuf - receive buffer
    
    recvcount - element count per block
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - iReduceScatterBlock
```
public final Request iReduceScatterBlock(java.nio.Buffer buf,
                                         int count,
                                         Datatype type,
                                         Op op)
                                  throws MPIException
```
    Combine values and scatter the results.
    Java binding of the MPI operation MPI_IREDUCE_SCATTER_BLOCK using MPI_IN_PLACE instead of the send buffer.
    
    Parameters:
    
    buf - receive buffer
    
    count - element count per block
    
    type - data type of each item in send buffer
    
    op - reduce operation
    
    Returns:
    
    communication request
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - reduceLocal
```
public static void reduceLocal(java.lang.Object inBuf,
                               java.lang.Object inOutBuf,
                               int count,
                               Datatype type,
                               Op op)
                        throws MPIException
```
    Apply the operation given by op element-wise to the elements of inBuf and inOutBuf with the result stored element-wise in inOutBuf.
    Java binding of the MPI operation MPI_REDUCE_LOCAL.
    
    Parameters:
    
    inBuf - input buffer
    
    inOutBuf - input buffer, will contain combined output
    
    count - number of elements
    
    type - data type of each item
    
    op - reduce operation
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - setName
```
public final void setName(java.lang.String name)
                   throws MPIException
```
    Sets the print name for the communicator.
    
    Parameters:
    
    name - name for the communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.
  - getName
```
public final java.lang.String getName()
                               throws MPIException
```
    Return the print name from the communicator.
    
    Returns:
    
    name of the communicator
    
    Throws:
    
    MPIException - Signals that an MPI exception of some sort has occurred.

Modifier and Type	Field	Description
`protected long`	`handle`
`protected static int`	`SELF`
`static int`	`TYPE_SHARED`
`protected static int`	`WORLD`

Modifier	Constructor	Description
`protected`	`Comm()`
`protected`	`Comm(long handle)`
`protected`	`Comm(long[] commRequest)`

Class Comm

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

TYPE_SHARED

SELF

WORLD

handle

Constructor Detail

Comm

Comm

Comm

Method Detail

setType

clone

dup

dup

iDup

iDup

dupWithInfo

dupWithInfo

getRequest

getSize

getRank

compare

free

isNull

setInfo

getInfo

disconnect

getGroup

isInter

createIntercomm

send

recv

sendRecv

sendRecvReplace

bSend

sSend

rSend

iSend

ibSend

isSend

irSend

iRecv

sendInit

bSendInit

sSendInit

rSendInit

recvInit

pack

unpack

packSize

iProbe

probe

createKeyval

freeKeyval

setAttr

getAttr

deleteAttr

getTopology

abort

setErrhandler

getErrhandler

callErrhandler

barrier

iBarrier

bcast

iBcast

gather

gather

iGather

iGather

gatherv

gatherv

gatherv

iGatherv

iGatherv