Catch RuntimeException

Question

During coding I want to catch some Exceptions from Runnables.

The code I tried to catch an Exception with:

public void fooBar(){
    //nullable value
    final String foo = null;
    try{
        new Thread(new Runnable() {
            @Override
            public void run() {
                if(foo == null){
                    //Only Exception that can be thrown from a Runnable
                    throw new RuntimeException("F.U.B.A.R.");
                }
            }
        }).start();
    }catch(Exception ex){
        //In my opinion the way to catch this Exception
        System.out.println(ex.getMessage());
    }
}

What I Expect to see as an output is:
F.U.B.A.R.

The output I'm getting:
Exception in thread "Thread-0" java.lang.RuntimeException: F.U.B.A.R.

The reason I need this is to put this Exception into my own so I can work with it properly down the line.

Does anyone know how to get the expected output instead of my current?

Answer 1

Because constructing Runnable and executing .start() between try and catch - did not throw exception. Runtime exception raised later, when thread executing "run" method.