Handler向子线程发送数据

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
private Button btn = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn =  findViewById(R.id.btn);
        HandlerThread t1 = new  HandlerThread();
        HandlerThread t2 = new HandlerThread();

        t1.start();
        t2.start();
        try {
            /**
             *   等待  使子线程内的handler能够初始化完毕，避免 时序错误带来的 mHandler = null
             */
            Thread.sleep(1000);
        } catch (InterruptedException e) {

        }

        t1.mHandler.sendMessage(new Message());
        t2.mHandler.sendMessage(new Message());
//        t1.stop();
//        t2.stop();
    }

    static  public class HandlerThread extends  Thread{
       public Handler  mHandler;
        @Override
        public void run() {
            Looper.prepare(); // 子线程无默认的 looper 需手动添加  
            mHandler = new Handler(){
                @Override
                public void handleMessage(Message msg) {
                    super.handleMessage(msg);
                    Log.d(TAG, "handleMessage:---------------------------- "+Thread.currentThread().getName());
                    Log.d(TAG, "Thread ID-----------------------"+Thread.currentThread().getId());
                }} ;
            Looper.loop(); // 循环
        };
        }
    }

日志输出：

2018-11-08 14:09:44.411 6000-6022/com.example.admin.handlertest D/MainActivity: handleMessage:---------------------------- Thread-2
2018-11-08 14:09:44.411 6000-6023/com.example.admin.handlertest D/MainActivity: handleMessage:---------------------------- Thread-3
2018-11-08 14:09:44.411 6000-6023/com.example.admin.handlertest D/MainActivity: Thread ID-----------------------43152
2018-11-08 14:09:44.411 6000-6022/com.example.admin.handlertest D/MainActivity: Thread ID-----------------------43151