Compile/Run/Debug Paths

The classpath specifies where the compiler looks for classes at compile time. At runtime, the java interpreter uses the classpath to find classes required by the running java program.

The sourcepath is used during debugging to locate the source files. The sourcepath is used by the compiler. If the compiler can't locate a .class file using the classpath, it looks for a corresponding .java file using the sourcepath.

The sourcepath is computed automatically from your workspace settings if the 'Plug' is pressed. If the plug is unpressed, you have to manually configure the sourcepath.