All-to-All Scatter/Gather

void Intracomm.Alltoall(Object sendbuf, int sendoffset,
                        int sendcount, Datatype sendtype,
                        Object recvbuf, int recvoffset,
                        recvcount, Datatype recvtype)

sendbuf	send buffer array
sendoffset	initial offset in send buffer
sendcount	number of items sent to each process
sendtype	datatype of send buffer items
recvbuf	receive buffer array
recvoffset	initial offset in receive buffer
recvcount	number of items received from any process
recvtype	datatype of receive buffer items

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.

void Intracomm.Alltoallv(Object sendbuf, int sendoffset,
                         int [] sendcount, int [] sdispls,
                         Datatype sendtype,
                         Object recvbuf, int recvoffset,
                         int [] recvcount, int [] rdispls,
                         Datatype recvtype)

sendbuf	send buffer array
sendoffset	initial offset in send buffer
sendcounts	number of items sent to each process
sdispls	displacements from which to take outgoing data
sendtype	datatype of each item in send buffer
recvbuf	receive buffer array
recvoffset	initial offset in receive buffer
recvcounts	number of elements received from each process
rdispls	displacements at which to place incoming data
recvtype	datatype of each item in receive buffer

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.