javaexceptionnullpointerexceptionthrowable

Add message to existing NullPointerException

I'm catching different kind of Exceptions in my method.

If the exception is a NullPointerException, I'd like to add a message to the existing exception.

Is there a way to add a message to an existing NullPointerException? I can't just create a new Exception, because I need the stacktrace etc.

My idea was to just create a new Exception like that:

new Exception("the message", myNullPointer);

But then, the output isn't as I need it, because that way, my stacktrace looks like that:

java.lang.Exception:
...bla
...bla

But I need it to keep the NullPointerException like that:

java.lang.NullPointerException:
...bla
...bla

Also it's important to say that I haven't access to the part where the initial NullPointer is created. So I can't add a message at start.

Edit: I know I should avoid NPEs. But I have to influence about the thrown NPE. So I have to react.

Solution

  • As pointed out in the comments, this may not be a good idea, especially because null exception might arise out of situations you didn't expect.

    Nevertheless, you can do exactly what you want like this:

    try {
    ...potentially throws exceptions...
} catch (Exception e) {
    RuntimeException re = new RuntimeException(e);
    re.setStackTrace(e.getStackTrace());
    throw re;
}