應用程序在進入背景時崩潰

Question

當我點擊主頁按鈕或當屏幕方向正在改變時，我的應用程序崩潰了我已經嘗試了很多解決方案，但都沒有工作。我已經知道它可能與終止線程連接，但即時通訊編程新，所以我將不勝感激任何幫助。 這是代碼和logcat。代碼是相當混亂的，因爲我已經嘗試實現這個解決方案和其他論壇

public class MainActivity extends Activity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    getActionBar().hide(); 
    setContentView(new GameView(this)); 
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);  
} 

}`

public class GameView extends SurfaceView implements 
      SurfaceHolder.Callback { 


p private KulaSprite kula; 
private PaletkaSprite paletka; 
private PaletkaSprite paletka2; 
private GameLogic mGameLogic; 
private boolean mGameIsRunning = false; 
private int punkty = 0; 
private String p1 = Integer.toString(punkty); 
private int punkty2 = 0; 
private String p2 = Integer.toString(punkty2); 
private float speed; 
Paint paint = new Paint(); 

public void start() { 
    if (!mGameIsRunning) { 
     mGameLogic.setGameState(GameLogic.RUNNING); 
     mGameLogic.start(); 
     mGameIsRunning = true; 
    } else { 
     mGameLogic.onResume(); 
    } 
} 


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

     setFocusable(true); 
     WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE); 
     Display display = wm.getDefaultDisplay(); 
     Point size = new Point(); 
     display.getSize(size); 
     int width = size.x; 
     int height = size.y; 
     kula = new KulaSprite(BitmapFactory.decodeResource(getResources(), R.drawable.kula), 600,300); 
     paletka = new PaletkaSprite(BitmapFactory.decodeResource(getResources(), R.drawable.paletka),15,height/2); 
     paletka2 = new PaletkaSprite(BitmapFactory.decodeResource(getResources(), R.drawable.paletka2), width-15,height/2); 
     mGameLogic = new GameLogic(getHolder(), this); 
     getHolder().addCallback(this); 
    } 

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

    @Override 
    public void surfaceCreated(SurfaceHolder holder){ 
     start(); 
    } 


    @Override 
    public void surfaceDestroyed(SurfaceHolder holder){ 
    } 

public void onDraw(Canvas canvas) { 
     canvas.drawColor(Color.rgb(00, 60, 10)); 
     paint.setTextSize((getHeight()*2)/3); 
     paint.setColor(Color.rgb(00, 80, 10)); 
     canvas.drawText(p1, getWidth()/12, (getHeight()*3)/4,paint); 
     canvas.drawText(p2, getWidth()/2, (getHeight()*3)/4,paint); 
     kula.draw(canvas); 
     paletka.draw(canvas); 
     paletka2.draw(canvas); 


    } 




public class GameLogic extends Thread { 

private SurfaceHolder _surfaceHolder; 
private GameView mGameView; 
private int game_state; 
public static final int PAUSE = 0; 
public static final int READY = 1; 
public static final int RUNNING = 2; 
private Object mPauseLock = new Object(); 
private boolean mPaused; 


public GameLogic(SurfaceHolder surfaceHolder, GameView mGameView) { 
    super(); 
    this._surfaceHolder = surfaceHolder; 
    this.mGameView = mGameView; 
} 



public void setGameState(int gamestate) { 
    this.game_state = gamestate; 
} 

public int getGameState(){ 
    return game_state; 
} 

public void onPause() { 
    synchronized (mPauseLock) { 
     mPaused = true; 
    } 
} 

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

@Override 
public void run() { 

    Canvas canvas; 
    canvas = null; 

    while (game_state == RUNNING) { 


     try { 
       canvas = this._surfaceHolder.lockCanvas(null); 
       synchronized (_surfaceHolder) { 
        this.mGameView.update(); 
        this.mGameView.onDraw(canvas); 

       } 
     } 

     finally { 
        if (canvas != null) { 
         _surfaceHolder.unlockCanvasAndPost(canvas); 
        } 
     } 
     synchronized (mPauseLock) { 
      while (mPaused) { 
       try { 
        mPauseLock.wait(); 
       } catch (InterruptedException e) { 
       } 
      } 
     } 
    } 
} 

}

03-30 14:19:24.880: D/libEGL(3010): loaded /system/lib/egl/libEGL_tegra.so 
03-30 14:19:24.910: D/libEGL(3010): loaded /system/lib/egl/libGLESv1_CM_tegra.so 
03-30 14:19:24.920: D/libEGL(3010): loaded /system/lib/egl/libGLESv2_tegra.so 
03-30 14:19:24.960: D/OpenGLRenderer(3010): Enabling debug mode 0 
03-30 14:19:29.270: W/dalvikvm(3010): threadid=11: thread exiting with uncaught   exception (group=0x41703ba8) 
03-30 14:19:29.270: E/AndroidRuntime(3010): FATAL EXCEPTION: Thread-2715 
03-30 14:19:29.270: E/AndroidRuntime(3010): Process: com.pingpong, PID: 3010 
03-30 14:19:29.270: E/AndroidRuntime(3010): java.lang.NullPointerException 
03-30 14:19:29.270: E/AndroidRuntime(3010):  at  com.GameView.onDraw(GameView.java:88) 
03-30 14:19:29.270: E/AndroidRuntime(3010):  at com.pingpong.GameLogic.run(GameLogic.java:60) 

Answer 1

按後退按鈕或旋轉你的設備會引起活動重新創建自己。由於您正在製作遊戲，因此將該屏幕鎖定到AndroidManifest文件所需的方向，以便進行方向更改不會觸發它。 http://developer.android.com/guide/topics/manifest/activity-element.html

要處理退出你需要重寫的活動onPause()或onStop()和停止執行你的遊戲循環用戶（背襯或家庭按）。由於它們在單獨的線程中，無論您是否在活動中，循環都會繼續執行。