android高手之路之使用runable需要注意的问题

看一段代码：

package com.example.threaddemo;

import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;

public class ThreadDemo extends Activity {
	private static final String TAG = "ThreadDemo";
	private int count = 0;
	private Handler mHandler =  new Handler();
	private Runnable mRunnable = new Runnable() {

		@Override
		public void run() {
			 Log.e(TAG, Thread.currentThread().getName() + " " +count);
			 ++count;
			 setTitle("" +count);
			//Performed once every two seconds
	        mHandler.postDelayed(mRunnable, 2000);
		}
	};

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_thread_demo);
		 mHandler.post(mRunnable);
	}

}

然后我们按返回键退出。

再进来。发现问题：

就是说，除了之前运行的runable，又多了一个

如何解决，在ondrestroy方法中添加

mHandler.removeCallbacks(mRunnable);

@Override
	protected void onDestroy() {
		mHandler.removeCallbacks(mRunnable);
		super.onDestroy();
	}