制，Android消息循环是针对线程的（每个线程都可以有自己的消息队列和消息循环）。
下面根据如下列子来开始进行Android消息处理系统的分析。
package com.XXX;

import android.app.Activity;
import android.os.Bundle;
import android.os.Message;
import android.util.Log;
import android.os.Handler;

public class MyHandler extends Activity {
static final String TAG = "Handler";
Handler h = new Handler(){
public void handleMessage (Message msg)
{
switch(msg.what)
{
case HANDLER_TEST:
Log.d(TAG, "Hanle Message in the handler thread, id = " + Thread.currentThread().getId() + "\n");
break;
}
}
};

static final int HANDLER_TEST = 1;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG, "The main thread id = " + Thread.currentThread().getId() + "\n");

new myThread().start();
setContentView(R.layout.main);
}