java - exception.getMessage() output with class name

Question

I'm trying to fix an issue, in my application I have this code

try {
  object1.method1();
} catch(Exception ex) {
   JOptionPane.showMessageDialog(nulll, "Error: "+ex.getMessage());
}

and the object1 would do something like that:

public void method1() {
   //some code...
   throw new RuntimeException("Cannot move file");
}

I get a messsage in my option pane like this: Error: java.lang.RuntimeException: Cannot move file

but I used getMessage and not toString method, so the name of the class shouldn′t appear, right?

What I am doing wrong? I already tryied with a lot of exceptions, even Exception itself. I'm looking to solve this no without the need to implement my own Exception subclass

PROBLEM SOLVED - thank you all!

The try and catch were actually being called in get() method from SwingWorker which constructs an ExecutionException with my exception thrown from doInBackground() I fixed doing this:

@Override
protected void done() {
    try {
        Object u = (Object) get();
        //do whatever u want
    } catch(ExecutionException ex) {
        JOptionPane.showMessageDialog(null, "Error: "+ex.getCause().getMessage());
    } catch(Exception ex) {
        JOptionPane.showMessageDialog(null, "Error: "+ex.getMessage());
    }
}

Answer 1

I think you are wrapping your exception in another exception (which isn't in your code above). If you try out this code:

public static void main(String[] args) {
    try {
        throw new RuntimeException("Cannot move file");
    } catch (Exception ex) {
        JOptionPane.showMessageDialog(null, "Error: " + ex.getMessage());
    }
}

...you will see a popup that says exactly what you want.

---

However, to solve your problem (the wrapped exception) you need get to the "root" exception with the "correct" message. To do this you need to create a own recursive method getRootCause:

public static void main(String[] args) {
    try {
        throw new Exception(new RuntimeException("Cannot move file"));
    } catch (Exception ex) {
        JOptionPane.showMessageDialog(null,
                                      "Error: " + getRootCause(ex).getMessage());
    }
}

public static Throwable getRootCause(Throwable throwable) {
    if (throwable.getCause() != null)
        return getRootCause(throwable.getCause());

    return throwable;
}

Note: Unwrapping exceptions like this however, sort of breaks the abstractions. I encourage you to find out why the exception is wrapped and ask yourself if it makes sense.