I use jdk6 and Eclipse3.2

When I run the following codes in eclipse:

---------------code begins---------------------------------
public class Test {
       public static void main(String[] args) {
               System.console().readPassword();
       }
}

---------------code ends------------------------------------

I get this:

--------------------------------
Exception in thread "main" java.lang.NullPointerException
       at HelloWorld.main(HelloWorld.java:3)
--------------------------------

But it runs well in command line.

Who can tell me why?
Is this a bug of eclipse or jdk6?
Thanks very much!