Android Handler

package com.example.myapp7;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
/**
 * UI线程发送数据，子线程接收数据。
 * @author shaobn
 * @date 2015-9-15
 * @packege com.example.myapp7MyApp7
 */
public class MainActivity extends ActionBarActivity {
    private Button button;
    private Handler handler;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button) this.findViewById(R.id.button1);
        button.setOnClickListener(new View.OnClickListener() {
            
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Message message = handler.obtainMessage();
                message.what = 8;
                handler.sendMessage(message);
            }
        });
        MyThread myThread = new MyThread();
        Thread thread = new Thread(myThread);
        thread.start();
    }
    class MyThread implements Runnable{
        @Override
        public void run() {
            // TODO Auto-generated method stub
            Looper.prepare();
            handler = new Handler(){
                @Override
                public void handleMessage(Message msg) {
                    // TODO Auto-generated method stub
                    Log.i("msg","--->>>"+String.valueOf(msg.what));
                }
            };
            Looper.loop();
        }
        
    }
}