A simple ``HelloWorld'' mpiJava program is shown in figure 4.2. The mpiJava API is modelled as closely as practical on the C++ binding defined in the MPI 2.0 standard (currently we only support the MPI 1.1 subset). A number of changes to argument lists are forced by of the restriction that arguments cannot be passed by reference in Java. In general outputs of mpiJava methods come through the result value of the function.
In this section we discuss the issues and special features of Java binding. As a result of the following changes mpiJava argument lists are often more concise than the corresponding C or C++ argument lists.