关于这段ProgressBar的代码看不懂

Question

package com.example.progressbartest;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
import android.widget.ProgressBar;

public class MainActivity extends ActionBarActivity {

private int[] data = new int[100];
int hasData = 0;
int status = 0;
ProgressBar bar, bar2;

Handler mHandler = new Handler() {

    public void handleMessage(Message msg) {

        if (msg.what == 0x111) {
            bar.setProgress(status);
            bar2.setProgress(status);
        }
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    bar=(ProgressBar) findViewById(R.id.bar);
    bar2=(ProgressBar) findViewById(R.id.bar2);
    new Thread()
    {
            public void run() {
        while(status<100){
            status=doWork();
            mHandler.sendEmptyMessage(0x111);
        }   
            }
            }.start();

    }
    public int doWork(){

        data[hasData++]=(int)(Math.random()*100);
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {

            e.printStackTrace();

        }
        return hasData;
}

}

Answer 1

 Handler mHandler = new Handler() {

    public void handleMessage(Message msg) {

        if (msg.what == 0x111) {//消息类型，与sendEmptyMessage(0x111)中传输的消息类型0x111是一致的
            bar.setProgress(status);//根据随机的数目更新进度条
            bar2.setProgress(status);
        }
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    bar=(ProgressBar) findViewById(R.id.bar);
    bar2=(ProgressBar) findViewById(R.id.bar2);
    new Thread()
    {
            public void run() {
        while(status<100){
            status=doWork();//产生一百个随机数个数
            mHandler.sendEmptyMessage(0x111);//因为在thread中是无法直接更新UI的，必须在UI现场中才能更新，所以通过handler发送消息,该消息由handler的handleMessage接收
        }   
            }
            }.start();

    }
    public int doWork(){

        data[hasData++]=(int)(Math.random()*100);  
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {

            e.printStackTrace();

        }
        return hasData;
}