DoModal[] does not return until the Java side sends an expression of the form EvaluatePacket[EndModal[args]].

EndJavaBlock[] ends an evaluation block equivalent to a JavaBlock, except that it works across a larger span than the evaluation of a single expression.

FrontEndLink[] returns the link to the front end that will be used by UseFrontEnd[].

GetClass[javaobject] returns the JavaClass that identifies the object's class.

GetJavaException[] returns the Java Exception object that was thrown in the most recent call from Mathematica to Java.

GetJVM[link] returns the JVM expression that corresponds to link, which was returned from InstallJava.

ImplementJavaInterface[interfaces, mappings] uses the Dynamic Proxy facility of Java to create a new Java class and return an object of that class that implements the named ...

JavaBlock[expr] causes all new Java objects returned to Mathematica during the evaluation of expr to be released when expr finishes. It is an error to refer to such an object ...

JavaClassPath[] returns the class search path in use by the Java runtime. This includes classes specified via the CLASSPATH environment variable (if any), directories and ...

JavaLink[] returns the MathLink LinkObject that is used to communicate with the J/Link Java runtime.