Question

我通过新的Handler（）调用多个处理程序.postDelayed（new Runnable（）..... 如果我点击返回按钮，我怎么能阻止它？

 public class Tag1 extends Oberklasse implements OnClickListener {

public Button btn;
//private Handler myHandler = new Handler();
Handler handler;
Runnable myRunnable;




@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.tt1);
    //Bildschirm soll anbleiben!!!
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

    //Lautstärke BUttons enable
    setVolumeControlStream(AudioManager.STREAM_MUSIC);





    getActionBar().setTitle("Tag 1");
    getActionBar().setDisplayHomeAsUpEnabled(true); 


    //tt1.xml beschriften
    TextView textView = (TextView)findViewById(R.id.uebung1);
    textView.setText("Übung 1:");

    TextView textView2 = (TextView)findViewById(R.id.uebung2);
    textView2.setText("Übung 2:");

    TextView textView3 = (TextView)findViewById(R.id.uebung3);
    textView3.setText("Übung 3:");

    TextView textView4 = (TextView)findViewById(R.id.uebung4);
    textView4.setText("Übung 4:");

    TextView textView5 = (TextView)findViewById(R.id.uebung5);
    textView5.setText("Übung 5:");

    TextView textView6 = (TextView)findViewById(R.id.uebung6);
    textView6.setText("Übung 6:");

    TextView textView7 = (TextView)findViewById(R.id.uebung7);
    textView7.setText("Übung 7:");






    //Button finden und Initialisieren!
    btn = (Button) findViewById(R.id.trainingsstart);
    btn.setOnClickListener(this);

}

@Override
public void onClick(View v) {





    Crunch();

    Handler handler=  new Handler();
    Runnable myRunnable = new Runnable() {
    public void run() {
        UnterarmLiegestütz1();
    }
    };
    handler.postDelayed(myRunnable,3000);

}

@Override 
public void onBackPressed() { 
    super.onBackPressed();
    uebung.stop();
    handler.removeCallbacks(myRunnable);

}






}

我有一个问题，我的处理程序没有像＃34; myHandler＆＃34; 。我该怎么处理？谢谢你的帮助！

现在我收到了这些错误：

03-28 17:47:03.662: E/AndroidRuntime(1961): FATAL EXCEPTION: main
03-28 17:47:03.662: E/AndroidRuntime(1961): java.lang.NullPointerException
03-28 17:47:03.662: E/AndroidRuntime(1961):     at de.basti12354.tage.uebungen.Tag1.onBackPressed(Tag1.java:120)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.app.Activity.onKeyUp(Activity.java:2159)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.KeyEvent.dispatch(KeyEvent.java:2647)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.app.Activity.dispatchKeyEvent(Activity.java:2389)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1860)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:3791)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3774)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3483)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3540)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3516)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:3666)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:1982)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1698)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1689)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:1959)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.os.MessageQueue.nativePollOnce(Native Method)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.os.MessageQueue.next(MessageQueue.java:132)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.os.Looper.loop(Looper.java:124)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at android.app.ActivityThread.main(ActivityThread.java:5103)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at java.lang.reflect.Method.invokeNative(Native Method)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at java.lang.reflect.Method.invoke(Method.java:525)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-28 17:47:03.662: E/AndroidRuntime(1961):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

您可以使用：

 Handler handler = new Handler()
 handler.postDelayed(new Runnable())

或者您可以使用：

 handler.removeCallbacksAndMessages(null);

<强>文档

public final void removeCallbacksAndMessages（Object token）

在API级别1中添加删除所有待处理的回调帖子并发送   obj是令牌的消息。如果token为null，则所有回调和   消息将被删除。

或者你也可以这样做：

Handler handler=  new Handler()
Runnable myRunnable = new Runnable() {
public void run() {
    // do something
}
};
handler.postDelayed(myRunnable,zeit_dauer2);

然后：

handler.removeCallbacks(myRunnable);

<强>文档

public final void removeCallbacks（Runnable r）

在API级别1中添加删除任何待处理的Runnable r帖子   在消息队列中。

public final void removeCallbacks（Runnable r，Object token）

修改

改变这个：

@Override public void onClick(View v) { Crunch(); Handler handler= new Handler(); Runnable myRunnable = new Runnable() {

要：

@Override public void onClick(View v) { Crunch(); handler= new Handler(); myRunnable = new Runnable() { /* ... */}

因为你有以下内容。在onCreate之前声明，但您重新声明，然后在导致NPE的onClick中初始化它。

Handler handler; // declared before onCreate Runnable myRunnable;

Answer 2

您可以定义布尔值，并在想要停止处理程序时将其更改为false。像这样......

boolean stop = false;

handler.postDelayed(new Runnable() {
    @Override
    public void run() {

        //do your work here..

        if (!stop) {
            handler.postDelayed(this, delay);
        }
    }
}, delay);

Answer 3

这可能是旧的，但对于那些寻找答案的人，你可以使用它......

public void stopHandler() {
   handler.removeMessages(0);
}

欢呼声

Answer 4

  Boolean condition=false;  //Instance variable declaration.

 //-----------------Inside oncreate--------------------------------------------------- 
  start =(Button)findViewById(R.id.id_start);
        start.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                starthandler();

                if(condition=true)
                {
                    condition=false;
                }


            }
        });

        stop=(Button) findViewById(R.id.id_stoplocatingsmartplug);

        stop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                stophandler();

            }
        });


    }

//-----------------Inside oncreate---------------------------------------------------

 public void starthandler()
    {

        handler = new Handler();
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {


                if(!condition)
                {
                    //Do something after 100ms 


                }

            }
        }, 5000);

    }


    public void stophandler()
    {
        condition=true;
    }

停止handler.postDelayed（）

4 个答案: