Why System.setProperty doesnot work?

Question

Dear ALL
i Want to use System.setProperty to set CLASSPATH
but i find it doesnot work. after run it,
CLASSPATH is same as before
below is code
before running java Test
classpath is null
after running java Test
classpath is still null,
How do i set classpath during program running time
and keep the change after running time?
import java.util.*;
public class Test
public static void main(String[] args)
System.out.println(System.getProperty("java.class.path"));
System.setProperty("java.class.path","C:\\C\\subc;"+System.getProperty("java.class.path"));
System.out.println(System.getProperty("java.class.path"));

Answer 1

Any properties you change using System.setProperty() go away as soon as the JVM exits -- they are changed in memory only.