Question

我有一个应用程序，它从片段内部每1秒运行一个postDelayed任务，使用一个使用复选框启用/禁用的处理程序。（工作正常）

当应用程序暂停时，runnable仍然会在后台生效，因为我想要它。但是，如果我恢复应用程序，我希望能够在使用handler.removeCallbacks（runnable）使checkBox变为unChecked时停止处理程序但是我得到一个NullPointerException。

有办法做到这一点吗？

＆＃13;

@Override
  public void onClick(View v) {
    // TODO Auto-generated method stub
    if(checkBox1.isChecked()) {
      if(deviceStart()==0) {
        //Failed to start service
        checkBox1.setChecked(false);
        Toast.makeText(getActivity(), "Failed to Start Service. Please Try Again...",Toast.LENGTH_SHORT).show();
      } else {
          handler = new Handler();
          handler.postDelayed(runnable, 1000);
      }
    } else {
      if(pocketHaloStop()==0) {
        //Failed to stop service
        checkBox1.setChecked(true);
        Toast.makeText(getActivity(), "Failed to Stop Service. Please Try Again...",Toast.LENGTH_SHORT).show();
      } else {
        handler.removeCallbacks(runnable); //This generates Null Pointer Exception if app is Resumed!
      }
    }
  });

＆＃13;

以下是Runnable和onPause / onResume：

的代码

＆＃13;

private Runnable runnable = new Runnable() {
		
		@Override
		public void run() {
			/* do what you need to do */

			handler.postDelayed(this, 1000);
		}
	};
    
    private void save(final boolean isChecked) {
		mContext = getActivity();
		SharedPreferences settings = mContext.getSharedPreferences("settings", Context.MODE_PRIVATE);
		SharedPreferences.Editor editor = settings.edit();
		editor.putBoolean("Check", isChecked);
		editor.commit();
	}

	private boolean load() { 
		mContext = getActivity();
		SharedPreferences settings = mContext.getSharedPreferences("settings", Context.MODE_PRIVATE);
		return settings.getBoolean("Check", false);
	}

    @Override
    public void onResume() {
    	super.onResume();
    	checkBox1 = (CheckBox)view.findViewById(R.id.checkEnable);
		checkBox1.setChecked(load());
		
    }

    @Override
    public void onPause() {
        super.onPause();
        save(checkBox1.isChecked());
        checkBox1.setOnClickListener(null);
    }

＆＃13;

Answer 1

将Handler的创建移动到onCreate（）。

 ....
 public void onCreate(Bundle savedInstanceState) {
     ...

     handler = new Handler();

     ...
 }

应用程序恢复后Android Runnable停止处理程序

1 个答案: