why System.setProperty donot work?

[walter wang]

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"));
}
}

[Bear Bibeault]

System properties and environment variables are not the same thing. And since envronment variables are a platform-dependent mechanism, Java doesn't have a supported means of accessing or setting them.
hth,
bear

[Cindy Glass]

In order to make a permanent change to the classpath on a Windows machine, you would have to interact with the Windows Registry, which would require finding the appropriate Microsoft dlls and using some JNI to invoke the correct methods.
Then you would do something similar for EACH target Operating System that you wanted to control.