// discovering system properties relevant to the classpath
import java.util.Properties;
//...

// the classpath
out.println( System.getProperty( "java.class.path" ) );

// extension directories whose jars are included on the classpath
out.println( System.getProperty( "java.ext.dirs" ) );

// low level classpath, includes system jars
out.println( System.getProperty( "java.library.path" ) );

// character to separate (not terminate!) entries on the classpath, ; for Windows : for unix.
out.println( System.getProperty( "path.separator" ) );

// To discover the default values for these properties, run Wassup either
// as an Applet or standalone (You will get quite different results each way.)
// See http://mindprod.com/applets/wassup.html