The RunJavaApplication class is a command line utility. It lets you set the environment (CLASSPATH and properties, for example) for the Java program. You specify the name of the Java program and its parameters, then you start the program. Once started, you can send input to the Java program which it receives via standard input. The Java program writes output to standard output and standard error.
The VRunJavaApplication utility has the same capabilities. The difference is VJavaApplicationCall uses a graphical user interface while JavaApplicationCall is a command line interface.