应用关闭并重新打开时Android崩溃

Question

我有一个非常简单的Android应用程序,只显示一个空白的白色屏幕.当我按下HOME按钮关闭应用程序,然后尝试再次打开应用程序,它崩溃,我得到"强制关闭"按钮.在Eclipse中我收到此错误,"ActivityManager:警告:活动未启动,因为正在为用户保留当前活动." 我该如何修复此崩溃？

public class HelloAndroid extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(   WindowManager.LayoutParams.FLAG_FULLSCREEN,   
                            WindowManager.LayoutParams.FLAG_FULLSCREEN); 

    setContentView(new Panel(this));
}

class Panel extends SurfaceView implements SurfaceHolder.Callback {

    private TutorialThread _thread;

    public Panel(Context context) {
        super(context);

        // register our interest in hearing about changes to our surface
        SurfaceHolder holder = getHolder();
        holder.addCallback(this);
        _thread = new TutorialThread(holder, this);

        setFocusable(true);
    }

    @Override
    public void onDraw(Canvas canvas) {

        // Clear the background
        canvas.drawColor(Color.WHITE);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // resize canvas here
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        _thread.setRunning(true);
        _thread.start();
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // simply copied from sample application LunarLander:
        // we have to tell thread to shut down & wait for it to finish, or else
        // it might touch the Surface after we return and explode
        boolean retry = true;
        _thread.setRunning(false);
        while (retry) {
            try {
                _thread.join();
                retry = false;
            } catch (InterruptedException e) {
                // we will try it again and again...
            }
        }
    }
}

class TutorialThread extends Thread {
    private SurfaceHolder _surfaceHolder;
    private Panel _panel;
    private boolean _run = false;

    public TutorialThread(SurfaceHolder surfaceHolder, Panel panel) {
        _surfaceHolder = surfaceHolder;
        _panel = panel;
    }

    public void setRunning(boolean run) {
        _run = run;
    }

    @Override
    public void run() {
        Canvas c;
        while (_run) {
            c = null;
            try {
                c = _surfaceHolder.lockCanvas(null);
                synchronized (_surfaceHolder) {
                    _panel.onDraw(c);
                }
            } finally {
                // do this in a finally so that if an exception is thrown
                // during the above, we don't leave the Surface in an
                // inconsistent state
                if (c != null) {
                    _surfaceHolder.unlockCanvasAndPost(c);
                }
            }
        }
    }
}

}

添加LogCat

03-15 15:36:05.579: INFO/AndroidRuntime(4441): NOTE: attach of thread 'Binder Thread #2' failed
03-15 15:36:05.719: DEBUG/AndroidRuntime(4449): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<<
03-15 15:36:05.719: DEBUG/AndroidRuntime(4449): CheckJNI is OFF
03-15 15:36:05.719: DEBUG/dalvikvm(4449): creating instr width table
03-15 15:36:05.759: DEBUG/AndroidRuntime(4449): --- registering native functions ---
03-15 15:36:05.969: INFO/ActivityManager(1294): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.example.helloandroid/.HelloAndroid }
03-15 15:36:05.979: DEBUG/Launcher(1371): onPause+
03-15 15:36:05.979: DEBUG/Launcher.DragController(1371): +endDrag: false
03-15 15:36:05.979: DEBUG/Launcher.DragController(1371): mDragging == false
03-15 15:36:05.979: DEBUG/Launcher.DragController(1371): -endDrag: false
03-15 15:36:05.979: DEBUG/Launcher(1371): onPause-
03-15 15:36:05.999: DEBUG/AndroidRuntime(4428): Shutting down VM
03-15 15:36:05.999: DEBUG/AndroidRuntime(4449): Shutting down VM
03-15 15:36:05.999: WARN/dalvikvm(4428): threadid=1: thread exiting with uncaught exception (group=0x4001d7e0)
03-15 15:36:06.009: DEBUG/dalvikvm(4449): Debugger has detached; object registry had 1 entries
03-15 15:36:06.009: INFO/AndroidRuntime(4449): NOTE: attach of thread 'Binder Thread #3' failed
03-15 15:36:06.029: ERROR/AndroidRuntime(4428): FATAL EXCEPTION: main
03-15 15:36:06.029: ERROR/AndroidRuntime(4428): java.lang.IllegalThreadStateException: Thread already started.
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at java.lang.Thread.start(Thread.java:1322)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at com.example.helloandroid.HelloAndroid$Panel.surfaceCreated(HelloAndroid.java:55)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.view.SurfaceView.updateWindow(SurfaceView.java:538)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.view.SurfaceView.onWindowVisibilityChanged(SurfaceView.java:206)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.view.View.dispatchWindowVisibilityChanged(View.java:3888)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:725)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:725)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.view.ViewRoot.performTraversals(ViewRoot.java:748)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1737)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.os.Looper.loop(Looper.java:123)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at android.app.ActivityThread.main(ActivityThread.java:4627)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at java.lang.reflect.Method.invokeNative(Native Method)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at java.lang.reflect.Method.invoke(Method.java:521)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
03-15 15:36:06.029: ERROR/AndroidRuntime(4428):     at dalvik.system.NativeStart.main(Native Method)
03-15 15:36:06.039: WARN/ActivityManager(1294):   Force finishing activity com.example.helloandroid/.HelloAndroid
03-15 15:36:06.541: WARN/ActivityManager(1294): Activity pause timeout for HistoryRecord{450300c0 com.example.helloandroid/.HelloAndroid}
03-15 15:36:06.549: DEBUG/Launcher(1371): onResume+
03-15 15:36:06.549: DEBUG/Launcher.DragController(1371): +endDrag: false
03-15 15:36:06.549: DEBUG/Launcher.DragController(1371): mDragging == false
03-15 15:36:06.549: DEBUG/Launcher.DragController(1371): -endDrag: false
03-15 15:36:06.549: DEBUG/Launcher(1371): onResume-
03-15 15:36:08.645: ERROR/KINETO(1370): KLOG0C3- xmk_QueryOSQueue SDL Queue empty : WAIT_FOREVER 

Answer 1

我在这里回答了这样的问题.

你得到的错误可能是由你造成的Thread(虽然没有看到完整的Logcat,但很难说).每次创建曲面时都会启动它,这会使您的应用程序崩溃,因为您无法调用Thread.start()两次.请查看上面的链接,以获得对问题的更深入描述以及如何解决问题.

由于我的解释不够,我将发布整个解决方案:

你的内心Runnable/Thread:

private Object mPauseLock = new Object();  
private boolean mPaused;

// Constructor stuff.      

// This should be after your drawing/update code inside your thread's run() code.
synchronized (mPauseLock) {
    while (mPaused) {
        try {
            mPauseLock.wait();
        } catch (InterruptedException e) {
        }
    }
}

// Two methods for your Runnable/Thread class to manage the thread properly.
public void onPause() {
    synchronized (mPauseLock) {
        mPaused = true;
    }
}

public void onResume() {
    synchronized (mPauseLock) {
        mPaused = false;
        mPauseLock.notifyAll();
    }
}

在你的SurfaceView班上:

private boolean mGameIsRunning;

@Override
public void surfaceCreated(SurfaceHolder holder) {
    // Your own start method.
    start();
}

public void start() {
    if (!mGameIsRunning) {
        thread.start();
        mGameIsRunning = true;
    } else {
        thread.onResume();
    }
}