H5DataSpaceId spaceID = H5S.create_simple( 1, new long[] { 1 } );
H5DataTypeId typeID = H5T.copy( H5T.H5Type.NATIVE_DOUBLE );
H5DataSetId datasetID = H5D.create( subGroupID, "PI", typeID, spaceID );
H5D.write<double>( datasetID, typeID, new H5Array<double>( new double[]{ 3.14152649 } ) );
H5D.close( datasetID );
H5T.close( typeID ); 
H5S.close( spaceID );
H5G.close( subGroupID );
H5G.close( groupID );
H5F.close( fileID );