处理程序不能正常工作

Question

首先，如果我的标题没有很好地描述我的问题，但我找不到更好的问题。

有一个简单的秒表应用程序，它有三个按钮开始，停止，重置和显示时间的文本视图。应用程序只有一个这样的活动：

public class StopwatchActivity extends AppCompatActivity { 

private int mNumberOfSeconds = 0; 
private boolean mRunning = false; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_stopwatch); 
    //if if uncomment this runner method and delete the runner inside onClickStart everything will work find 
    //runner() 

} 

public void onClickStart(View view){ 
    mRunning = true; 
    runner(); 
} 

public void onClickStop(View view){ 
    mRunning = false; 
} 

public void onClickReset(View view){ 
    mRunning = false; 
    mNumberOfSeconds = 0; 

} 

public void runner(){ 
    final TextView timeView = (TextView) findViewById(R.id.time_view); 
    final Handler handler = new Handler(); 
    handler.post(new Runnable() { 
     @Override 
     public void run() { 
      int hours = mNumberOfSeconds/3600; 
      int minutes = (mNumberOfSeconds%3600)/60; 
      int second = mNumberOfSeconds%60; 
      String time = String.format("%d:%02d:%02d" , hours , minutes , second); 
      timeView.setText(time); 
      if (mRunning){ 
       mNumberOfSeconds++; 
      } 
      handler.postDelayed(this , 1000); 
     } 
    }); 

} 
} 

我的问题是，当我评论亚军（）在onClickStart方法，并把它在onCreate方法一切正常。但是当我更改上面的代码时，代码仍在运行，但是在按停止按钮之后，再次按下启动按钮，第二个代码将以非常快的速度增加4或5。 任何人都可以解释我有什么区别这两种模式？

Answer 1

声明你处理全球

public void runner(){ 
    timeView = (TextView) findViewById(R.id.time_view); 
    handler = new Handler(); 
    runnable = new Runnable() { 
     @Override 
     public void run() { 
      int hours = mNumberOfSeconds/3600; 
      int minutes = (mNumberOfSeconds%3600)/60; 
      int second = mNumberOfSeconds%60; 
      String time = String.format("%d:%02d:%02d" , hours , minutes , second); 
      timeView.setText(time); 
      if (mRunning){ 
       mNumberOfSeconds++; 
      } 
      handler.postDelayed(this , 1000); 
     } 
    } 
    handler.post(runnable); 

} 

按钮功能

public void onClickStart(View view){ 
    if(handler != null) { 
     //restart the handler to avoid duplicate runnable 
     handler.removeCallbacks(runnable);//or this handler.removeCallbacksAndMessages(null); 
    } 
    mRunning = true; 
    runner(); 
} 

public void onClickStop(View view){ 
    mRunning = false; 
    handler.removeCallbacks(runnable); // this will stop the handler from working 
}