If your Java program is structured as an applet, you can use the Java Applet launch configuration. This launch configuration uses information derived from the workbench preferences and your program's Java project to launch the program.
You can also launch a Java applet by selecting a project instead of the compilation unit or class file. You will be prompted to select a class from those classes that extend Applet. (If only one applet class is found in the project, that class is launched as if you selected it.)
Re-launching a program
Running and debugging
Stepping through the execution of a program