Gather

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

Java binding of the MPI operation MPI_GATHER. The value sendoffset is a subscript in sendbuf, defining the position of the first item of the message to be sent. The value recvoffset is a subscript in recvbuf, defining the position into which the first item of the gathered data will be copied.

void Intracomm.Gatherv(Object sendbuf, int sendoffset,
                       int sendcount, Datatype sendtype,
                       Object recvbuf, int recvoffset,
                       int [] recvcount, int [] displs,
                       Datatype recvtype, int root)

Java binding of the MPI operation MPI_GATHERV. Arguments other than displs as for Gather. (Note that if recvtype is a derived data type, displs is in units of the derived data type, unlike recvoffset, which is in units of the base type.)