Explicitly and without apology a marketing vehicle MaryMaryQuiteContrary

$ cat A.java 
public class A {
  public static void sneakyThrow(Throwable t) {
    B.sneakyThrow(t); 
  }
  public static void main(String[] args) {
    sneakyThrow(new Throwable());
  }
}

$ cat B.java 
public class B {
  public static void sneakyThrow(Throwable t) {
  }
}

$ jikes A.java B.java 

$ vim B.java 

$ cat B.java 
public class B {
  public static void sneakyThrow(Throwable t) 
      throws Throwable {
    throw t;
  }
}

$ jikes B.java 

$ java -cp . A
java.lang.Throwable
        at A.main(A.java:6)
Exception in thread "main" 

Posted by Bob Lee on September 03, 2004 at 03:08 PM PDT #

Mary, I believe that the foam armchair is a cell phone holder. Well I have something similar that was sold as such.

Posted by Alan Hargreaves on September 04, 2004 at 02:02 AM PDT #

Posted by Unknown on September 04, 2004 at 03:46 PM PDT #

import java.lang.reflect.*;

public class ThreadStop {

    public static void sneakyThrow(Throwable t) throws Exception {
        Method resume0 = Thread.class.getDeclaredMethod("resume0", null);
        Method stop0 = Thread.class.getDeclaredMethod("stop0", new Class[] { Object.class });
        resume0.setAccessible(true);
        stop0.setAccessible(true);
        Thread thread = Thread.currentThread();
        resume0.invoke(thread, null);
        stop0.invoke(thread, new Object[] { t });
    }

    public static void main(String[] args) throws Exception {
        sneakyThrow(new Exception("Die!"));
    }
}

Posted by Kris Schneider on September 04, 2004 at 05:51 PM PDT #

Posted by James on September 06, 2004 at 04:57 AM PDT #

Posted by Click and Hack the Type-it Brothers on September 06, 2004 at 06:50 AM PDT #

Posted by Mridul on September 07, 2004 at 03:31 AM PDT #

public class DieJavaDie {
  private static class StackSmasher implements Runnable {
    public void run() {
      Object o = null;
      o.hashCode();
    }
  }

  private static class SneakyThreadGroup extends ThreadGroup {
    private Throwable toThrow;

    public SneakyThreadGroup(ThreadGroup parent, String name, Throwable toThrow) {
      super(parent, name);
      this.toThrow = toThrow;
    }

    public void uncaughtException(Thread t, Throwable e) {
      super.uncaughtException(t, toThrow);
    }
  }

  public static void main(String []args) {
    ThreadGroup parent = Thread.currentThread().getThreadGroup();
    ThreadGroup child = new SneakyThreadGroup(parent, "child", new ClassCastException("0wn3d"));
    Thread runner = new Thread(child, new StackSmasher());
    runner.start();
  }
}

Uses ThreadGroups uncaughtException handling to sneakily exchange an exception for another. It uses a separate thread that creates a harmless exception and then can swap in anything you like in the thread group exception propagation chain.

I could have made main a method that accepts a parameter, but the idea is the same anyway: use helper class to work around thread group backdoor, throw runtime exception, change it in the backdoor in the desired exception, profit.

cheers, dalibor topic

Posted by Dalibor Topic on September 07, 2004 at 08:30 AM PDT #

public class ThreadStop {

    public static void sneakyThrow(final Throwable t) {
        InvocationHandler h = new InvocationHandler() {
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                throw t;
            }
        };
        Object proxy = Proxy.newProxyInstance(ThreadStop.class.getClassLoader(),
                                              new Class[] { Cloneable.class },
                                              h);
        proxy.toString();
    }
    ...
}

java.lang.reflect.UndeclaredThrowableException
        at $Proxy0.toString(Unknown Source)
        at ThreadStop.sneakyThrow(ThreadStop.java:16)
        at ThreadStop$2.run(ThreadStop.java:24)
Caused by: java.lang.InterruptedException: Die!
        ... 1 more

Posted by Kris Schneider on September 07, 2004 at 09:21 AM PDT #

public static void sneakyThrow(Throwable t) {
    throw new UndeclaredThrowableException(t);
}

Posted by Kris Schneider on September 07, 2004 at 11:39 AM PDT #

Posted by Bob Lee on September 07, 2004 at 11:50 AM PDT #

Posted by Kris Schneider on September 07, 2004 at 12:14 PM PDT #

public class DieJavaDie {
    private static class StackSmasher implements Runnable {
	public void run() {
	    Object o = null;
	    o.hashCode();
	}
    }

    private static class SneakyThreadGroup extends ThreadGroup {
	private Throwable toThrow;
	
	public SneakyThreadGroup(ThreadGroup parent, String name, Throwable toThrow) {
	    super(parent, name);
	    this.toThrow = toThrow;
	}

	public void uncaughtException(Thread t, Throwable e) {
	    super.uncaughtException(t, toThrow);
	}
    }

    private static class SneakyThrower {
	public static void sneakyThrow(Throwable t) {
	    ThreadGroup parent = Thread.currentThread().getThreadGroup();
	    ThreadGroup child = new SneakyThreadGroup(parent, "child", t);
	    Thread runner = new Thread(child, new StackSmasher());
	    runner.start();
	}
    }

    public static void main(String []args) {
	// demonstrate the technique:
	// despite no method in this code being declared as throwing an
	// exception, this call will result in an
	// ClassCastException with the desired message being thrown
	SneakyThrower.sneakyThrow(new ClassCastException("Own3d, 0nc3 m0r3"));
    }
}

Posted by Dalibor Topic on September 07, 2004 at 01:25 PM PDT #

Posted by Bob Lee on September 07, 2004 at 01:45 PM PDT #

Posted by Kris Schneider on September 07, 2004 at 01:58 PM PDT #

Posted by Kris Schneider on September 07, 2004 at 02:58 PM PDT #

Posted by Chris Nokleberg on September 10, 2004 at 10:03 AM PDT #

Posted by ropo on December 12, 2004 at 06:36 PM PST #