Question

I’m using Handler and HandlerThread to perform asynchronous loading in my application, but something is going wrong, for example:

handler.postDelayed(new Runnable() {
    @Override
    public void run() {
        .....................
    }

}, 100);

this handler wrip (sic) in a new HandlerThread and is created in onCreate().

It seems like that is no problem, however there are times when an error appears, one example of this is a NullPointerException caused on this handler – it is stable before – but when I test on 2.1 version emulator this happen some times and I can’t solve it, is thee any one that can help me?

Answer 1

have you considered race conditions in your code? it sounds like the handler code is not performing proper synchonization – and might sometimes see changes from a different thread – which again causes your nullPointer exception.

try wrapping your problem code in a synchonized block – or if you are using primitve types only – move to volatile or atomic types.