膨脹布局NullPointerException

Question

我想在玩家死亡時給布局充氣（游戲超出布局）。 我這樣嘗試過：

View GameOverDialog;

LayoutInflater myInflater = (LayoutInflater)getApplicationContext().getSystemService(getApplicationContext().LAYOUT_INFLATER_SERVICE);
GameOverDialog = myInflater.inflate(R.layout.lose, null, false);
rlGame.addView(GameOverDialog);
GameOverDialog.setVisibility(View.GONE);

玩家死亡時：

private void lose(){
    GameOverDialog.setVisibility(View.VISIBLE);
}

我還使用處理程序，以便玩家死亡時可以發送消息：

final static int DEATH = 0, LOSE = 1;

final Handler handler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        if (msg.what == DEATH) {
            //play music
            postDelayed(new Runnable() {
                @Override
                public void run() {
                    Message msg = handler.obtainMessage();
                    msg.what = LOSE;
                    handler.sendMessage(msg);
                }
            }, 1000);
        }
        if (msg.what == LOSE) {
            lose();
        }
        super.handleMessage(msg);
    }
};

但是，當處理程序調用Los（）方法時，應用程序崩潰了，我得到了NullPointerException。 我希望有一個人可以幫助我 ：）。

提前致謝！
Joeri。

編輯

全班：

public class Game extends Activity {

final static int DEATH = 0, LOSE = 1;
RelativeLayout rlGame;
GamePanel game_panel;
private int ScreenWidth, ScreenHeight;
View GameOverDialog;
ImageView retry, quit;
TextView textRetry, textQuit;

final Handler handler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        if (msg.what == DEATH) {
            //play music
            postDelayed(new Runnable() {
                @Override
                public void run() {
                    Message msg = handler.obtainMessage();
                    msg.what = LOSE;
                    handler.sendMessage(msg);
                }
            }, 1000);
        }
        if (msg.what == LOSE) {
            lose();
        }
        super.handleMessage(msg);
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.game);

    rlGame = (RelativeLayout) findViewById(R.id.rlGame);
    DisplayMetrics dm = new DisplayMetrics();
    this.getWindowManager().getDefaultDisplay().getMetrics(dm);

    final int height = dm.heightPixels;
    final int width = dm.widthPixels;

    game_panel = new GamePanel(getApplicationContext(), width, height, rlGame);
    rlGame.addView(game_panel);

    LayoutInflater myInflater = (LayoutInflater)getApplicationContext().getSystemService(getApplicationContext().LAYOUT_INFLATER_SERVICE);
    GameOverDialog = myInflater.inflate(R.layout.lose, null, false);
    rlGame.addView(GameOverDialog);
    retry = (ImageView) GameOverDialog.findViewById(R.id.retry);
    retry.setOnTouchListener(new TouchButton(retry, textRetry));
    quit = (ImageView) GameOverDialog.findViewById(R.id.quit);
    quit.setOnTouchListener(new TouchButton(quit, textQuit));
    textRetry = (TextView)GameOverDialog.findViewById(R.id.textRetry);
    textQuit = (TextView)GameOverDialog.findViewById(R.id.textQuit);
    GameOverDialog.setVisibility(View.GONE);
}

@Override
public void onBackPressed() {
}

@Override
protected void onStop() {
    super.onStop();
}

private void lose() {
    GameOverDialog.setVisibility(View.VISIBLE);
}

}

我還嘗試在onBackPressed方法中將可見性設置為VISIBLE，這行得通，我不知道為什么，但是我認為在處理程序中出了點問題...

Answer 1

避免在不需要時使用getApplicationContext() ：

game_panel = new GamePanel(this, width, height, rlGame);
rlGame.addView(game_panel);

LayoutInflater myInflater = (LayoutInflater)
        getSystemService(Context.LAYOUT_INFLATER_SERVICE);

編輯：

根據您的評論（下一次，請更新您的問題），似乎在設置變量的onCreate之前調用了handleMessage。 因此，在字段初始化之后設置您的監聽器：

Handler handler;

@Override
protected void onCreate(Bundle savedInstanceState) {
    ...
    // Init field
    GameOverDialog = myInflater.inflate(R.layout.lose, null, false);
    // Set the handler
    handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            if (msg.what == DEATH) {
                //play music
                postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        Message msg = handler.obtainMessage();
                        msg.what = LOSE;
                        handler.sendMessage(msg);
                    }
                }, 1000);
            }
            if (msg.what == LOSE) {
                lose();
            }
            super.handleMessage(msg);
        }
    };
    ...
}