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POSurfaceView crashes on surfaceChange Android
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copied!<p>I have made an example that extend <code>SurfaceView</code> and <code>Thread</code> to draw some objects on canvas in Android but I'm facing two problems.</p> <ol> <li><p>When press back button the application closed and then show me that "Unfortunately, your example has stopped".</p></li> <li><p>When change the orientation from "Portrait" to "Landscape" or VS , the application failed to adjust the new screen and does not update the drawing then it is crash and show the same message "Unfortunately, your example has stopped".</p></li> </ol> <p>Please review code:</p> <pre><code>@Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // TODO implement this method holder.getSurface().setSize(width, height); holder.setFormat(format); } @Override public void surfaceCreated(SurfaceHolder holder) { // at this point the surface is created and // we can safely start the game loop thread.setRunning(true); thread.start(); } @Override public void surfaceDestroyed(SurfaceHolder holder) { // tell the thread to shut down and wait for it to finish // this is a clean shutdown boolean retry = true; while (retry) { try { thread.join(); retry = false; } catch (InterruptedException e) { // try again shutting down the thread } } } </code></pre> <p>When I check the logcat I found the following line that the problem in this part</p> <pre><code>@Override public void run() { Canvas canvas; // initialise timing elements for stat gathering initTimingElements(); long beginTime; // the time when the cycle begun long timeDiff; // the time it took for the cycle to execute int sleepTime; // ms to sleep (<0 if we're behind) int framesSkipped; // number of frames being skipped sleepTime = 0; while (running) { canvas = null; // try locking the canvas for exclusive pixel editing // in the surface try { canvas = this.surfaceHolder.lockCanvas(); LoggerHandler.log("canvas : " + canvas); synchronized (surfaceHolder) { beginTime = System.currentTimeMillis(); framesSkipped = 0; // resetting the frames skipped // update game state this.gamePanel.update(); // render state to the screen // draws the canvas on the panel this.gamePanel.render(canvas); // calculate how long did the cycle take timeDiff = System.currentTimeMillis() - beginTime; // calculate sleep time sleepTime = (int) (FRAME_PERIOD - timeDiff); if (sleepTime > 0) { // if sleepTime > 0 we're OK try { // send the thread to sleep for a short period // very useful for battery saving Thread.sleep(sleepTime); } catch (InterruptedException e) { } } while (sleepTime < 0 && framesSkipped < MAX_FRAME_SKIPS) { // we need to catch up this.gamePanel.update(); // update without rendering sleepTime += FRAME_PERIOD; // add frame period to check // if in next frame framesSkipped++; } // for statistics framesSkippedPerStatCycle += framesSkipped; // calling the routine to store the gathered statistics storeStats(); } } finally { // in case of an exception the surface is not left in // an inconsistent state if (canvas != null) { surfaceHolder.unlockCanvasAndPost(canvas); } } // end finally } } </code></pre> <p>The problem in this line:</p> <pre><code>canvas = this.surfaceHolder.lockCanvas(); </code></pre> <p>It is return <code>null</code> when change the orientation.</p>

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