Android异步更新UI的方式之使用Handler消息传递机制

package com.example.runonuithreadtest; 
import android.app.Activity; 
import android.os.Bundle; 
import android.os.Handler; 
import android.widget.TextView; 
public class MainActivity extends Activity { 
private TextView tv; 
Handler handler = new Handler() 
{ 
  public void handleMessage(android.os.Message msg) { 
   if(msg.what==0x123) 
   { 
    tv.setText("更新后的TextView"); 
   } 
  }; 
}; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
  tv = (TextView) findViewById(R.id.tv); 
  new MyThread().start(); 
} 
class MyThread extends Thread 
{ 
  @Override 
  public void run() { 
   //延迟两秒更新 
   try { 
    Thread.sleep(2000); 
   } catch (InterruptedException e) { 
    // TODO Auto-generated catch block 
    e.printStackTrace(); 
   } 
   handler.sendEmptyMessage(0x123); 
  } 
} 
}