Android笔记（三十二） Android中线程之间的通信（四）主线程给子线程发送消息

         之前的例子都是我们在子线程（WorkerThread）当中处理并发送消息，然后在主线程（UI线程）中获取消息并修改UI，那么可以不可以在由主线程发送消息，子线程接收呢？我们按照之前的思路写一下代码：

package cn.lixyz.handlertest;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;


public class MainActivity extends Activity {

    private Button button;
    private Handler handler;
    private int i = 0;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        button = (Button) findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d("TTTT", "onClick:" + Thread.currentThread().getName());
                Message msg = handler.obtainMessage();
                handler.sendMessage(msg);
            }
        });

        WorkerThread wt = new WorkerThread();
        wt.start();
    }


    class WorkerThread extends Thread {
        @Override
        public void run() {
            super.run();
            handler = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    super.handleMessage(msg);
                    Log.d("TTTT", "收到了消息对象");
                }
            };
        }
    }
}

MainActivity.java