Question

I’m working with android & canvas, my code works flawlessly for other than when the display resolution changes (ie. rotating the device) the app forcecloses and log cat shows:

FATAL EXCEPTION: Thread-367

java.lang.NullPointerException

at …doDraw()

The line it links the error to contains:

canvas.drawARGB(255, 0, 0, 0);

But I believe it doesn’t matter as long as it’s trying to draw something and shows the first thing I’m trying to draw.

Here’s my run loop:

        @Override
    public void run() {
        while (mPlaying) {
            Canvas c = null;
            try {
                c = mSurfaceHolder.lockCanvas(null);
                synchronized (mSurfaceHolder) {
                    if (mPlaying == true) updatePosition();
                    doDraw(c);
                }
        } finally {
                if (c != null) {
                    mSurfaceHolder.unlockCanvasAndPost(c);
                }
            }
        }
    }

Which I took directly from the LunarLander example. Now the crash doesn’t happen every time I rotate, but about 75% of the time.

Any ideas? Thanks 🙂

Answer 1

this may help you

           if your android:targetSdkVersion="12" or less
     android:configChanges="orientation|keyboardHidden">

      if your  android:targetSdkVersion="13" or more
  android:configChanges="orientation|keyboardHidden|screenSize">