package de.bvb.test;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import java.lang.ref.WeakReference;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        new Thread(new Runnable() {            @Override            public void run() {                //3.子线程中发送消息                handler.sendEmptyMessage(1);            }        }).start();    }    @Override    protected void onDestroy() {        super.onDestroy();        //4.在onDestroy把消息对象从消息队列移除        handler.removeCallbacksAndMessages(null);    }    //2.创建handler的实例    private Handler handler = new MyHandler(this);    //1.创建静态的自定义Handler类    static class MyHandler extends Handler {        private WeakReference
     
       mWeakReference;        //传入activity,加上弱引用        public MyHandler(Activity activity) {            mWeakReference = new WeakReference<>(activity);        }        //在handleMessage处理业务        @Override        public void handleMessage(Message msg) {            Activity activity = mWeakReference.get();            if (activity != null) {                switch (msg.what) {                    case 1:                        break;                    default:                        break;                }            }        }    }}