Question

I’m writing an Android app in Eclipse, and displaying some text on screen using a TextView. A different thread sometimes changes the text of this view, with the following code:

runOnUiThread(new Runnable() {

    @Override
    public void run() {
        view.setText(newLyric);
    }
});

I wanted to debug the setText line to check that the correct String was being passed in (as for some text, it was not being word-wrapped to fit the screen, and for other text it was, but that’s a different issue). When I put a breakpoint on that line, the text is always word-wrapped. And when I disable/remove the breakpoint, the text that usually doesn’t get word-wrapped (it’s deterministic) is not word-wrapped.

This doesn’t make much sense to me. I’ve seen this question, and I understand the reasoning behind that, but I can’t see why that would be the issue here. Can anyone shed some light on this? I’m testing on a device, if that makes any difference.

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Edit: It turns out it was a race condition, now I just have to work out how to fix it… Obviously I could only pick one ‘correct’ answer, but thank you to all of you for the helpful comments 🙂

Answer 1

Things like this are sometimes/often a sign of a race condition.

Putting a breakpoint eliminates the race (so a “rogue” thread that was overriding the value by running later is now finished by the time your breakpoint is caught, as an example).

Or it’s a clear case of Heisenbug 🙂