Is there already a StopWatch class for android and why doesn't my implementation work?

Question

Lately I saw http://developer.android.com/reference/android/os/CountDownTimer.html and wondered if there is an respective class for stop watches since I want to tell the user of my App how long he's already trying to solve the puzzle. I mean it isn't that complicated to program such a stop watch on your own. I tried something like

    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            while (true) {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                }
                long seconds = (System.currentTimeMillis() - t) / 1000;
                statusBar.setText(String.format("%02d:%02d", seconds / 60, seconds % 60));
            }
        }

    };
    statusBar.post(runnable);

But bizarrely the layout of my activity isn't inflated anymore since I have this statusBar.post(runnable); in the end of the acitivity's onCreate method meaning that after starting the app I only see a white screen instead of the normal gui.

Answer 1

You should use a Chronometer.

But anyway, your code can work if you remove the sleep from UI thread.

private final Runnable mRunnable = new Runnable() {
    @Override
    public void run() {
        if (mStarted) {
            long seconds = (System.currentTimeMillis() - t) / 1000;
            statusBar.setText(String.format("%02d:%02d", seconds / 60, seconds % 60));
            handler.postDelayed(runnable, 1000L);
        }
    }

};

private Hanlder mHandler;
private boolean mStarted;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mHandler = new Handler();
}

@Override
protected void onStart() {
    super.onStart();
    mStarted = true;
    mHandler.postDealyed(runnable, 1000L);
}

@Override
protected void onStop() {
    super.onStop();
    mStarted = false;
    mHandler.removeCallbacks(mRunnable);
}