Most of the familiar gl_* function calls and constants in C/C++ modules can be made from Java using GridlabD.*, such as GridlabD.error() and GridlabD.TS_NEVER. Class registration is made through static calls to GClass, and Gridlab object construction through static GObject methods.
Java modules must be careful to handle any exceptions internally, as uncaught exceptions may have unexpected consequences within the JVM.