Uncatchable ChuckNorrisException

Question

Is it possible to construct a snippet of code in Java that would make a hypothetical java.lang.ChuckNorrisException uncatchable?

Thoughts that came to mind are using for example interceptors or aspect-oriented programming.

Answer 1

I haven't tried this, so I don't know if the JVM would restrict something like this, but maybe you could compile code which throws ChuckNorrisException, but at runtime provide a class definition of ChuckNorrisException which does not extend Throwable.

UPDATE:

It doesn't work. It generates a verifier error:

Exception in thread "main" java.lang.VerifyError: (class: TestThrow, method: ma\
in signature: ([Ljava/lang/String;)V) Can only throw Throwable objects
Could not find the main class: TestThrow.  Program will exit.

UPDATE 2:

Actually, you can get this to work if you disable the byte code verifier! (-Xverify:none)

UPDATE 3:

For those following from home, here is the full script:

Create the following classes:

public class ChuckNorrisException
    extends RuntimeException // <- Comment out this line on second compilation
{
    public ChuckNorrisException() { }
}

public class TestVillain {
    public static void main(String[] args) {
        try {
            throw new ChuckNorrisException();
        }
        catch(Throwable t) {
            System.out.println("Gotcha!");
        }
        finally {
            System.out.println("The end.");
        }
    }
}

Compile classes:

javac -cp . TestVillain.java ChuckNorrisException.java

Run:

java -cp . TestVillain
Gotcha!
The end.

Comment out "extends RuntimeException" and recompile ChuckNorrisException.java only :

javac -cp . ChuckNorrisException.java

Run:

java -cp . TestVillain
Exception in thread "main" java.lang.VerifyError: (class: TestVillain, method: main signature: ([Ljava/lang/String;)V) Can only throw Throwable objects
Could not find the main class: TestVillain.  Program will exit.

Run without verification:

java -Xverify:none -cp . TestVillain
The end.
Exception in thread "main"

Answer 2

After having pondered this, I have successfully created an uncatchable exception. I chose to name it JulesWinnfield, however, rather than Chuck, because it is one mushroom-cloud-laying-mother-exception. Furthermore, it might not be exactly what you had in mind, but it certainly can't be caught. Observe:

public static class JulesWinnfield extends Exception
{
    JulesWinnfield()
    {
        System.err.println("Say 'What' again! I dare you! I double dare you!");
        System.exit(25-17); // And you shall know I am the LORD
    }
}
    
    
public static void main(String[] args)
{       
    try
    {
        throw new JulesWinnfield();
    } 
    catch(JulesWinnfield jw)
    {
        System.out.println("There's a word for that Jules - a bum");
    }
}

Et voila! Uncaught exception.

Output:

run:

Say 'What' again! I dare you! I double dare you!

Java Result: 8

BUILD SUCCESSFUL (total time: 0 seconds)

When I have a little more time, I'll see if I can't come up with something else, as well.

Also, check this out:

public static class JulesWinnfield extends Exception
{
    JulesWinnfield() throws JulesWinnfield, VincentVega
    {
        throw new VincentVega();
    }
}

public static class VincentVega extends Exception
{
    VincentVega() throws JulesWinnfield, VincentVega
    {
        throw new JulesWinnfield();
    }
}


public static void main(String[] args) throws VincentVega
{
    
    try
    {
        throw new JulesWinnfield();
    }
    catch(JulesWinnfield jw)
    {
        
    }
    catch(VincentVega vv)
    {
        
    }
}

Causes a stack overflow - again, exceptions remain uncaught.

Answer 3

With such an exception it would obviously be mandatory to use a System.exit(Integer.MIN_VALUE); from the constructor because this is what would happen if you threw such an exception ;)