Interesting Anti-Debugging Technique for standalone Java app

// (c) 2013 http://twitter.com/mihi42 //

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import sun.misc.Unsafe;

public class CrashWhenDebugged {
    public static void main(String[] args) throws Exception {
        Field ff = Unsafe.class.getDeclaredField("theUnsafe");
        ff.setAccessible(true);
        Unsafe u = (Unsafe) ff.get(null);
        final Field g = Thread.class.getDeclaredField("group");
        g.setAccessible(true);
        Thread t = new Thread("Killer") {
            public void run() {
                try {
                    Thread.sleep(200);
                    g.set(this, null);
                } catch (Exception ex) {
                }
            }
        };
        u.putInt(t, u.objectFieldOffset(g), 3);
        Method m = Thread.class.getDeclaredMethod("start0");
        m.setAccessible(true);
        m.invoke(t);
        t.join();
        System.out.println("I survived!");
    }
}