Multi-Threaded Android: Handler, Thread, Looper, and Message Queue

雨点打透心脏的1/2处 2022-12-28 04:17 131阅读 0赞

主线程就是一个handler thread，负责处理整个app的类似于callbacks等事件

**Thread**

1、

class Test extends Thread{
    
       @Override
       public void run() {
           Log.d("Threading", "test class thread is  > " + Thread.currentThread().getName());
    }
    }

2、

class Test implements Runable{
    
       @Override
       public void run() {
           Log.d("Threading", "test class thread is  > " + Thread.currentThread().getName());
    }
    }

new Test.start();

![Image for post][]3\\

3、

private void yourMethodName(){
    new Thread(new Runnable() {
        @Override
        public void run() {
                try {
                 yourActivity.runOnUiThread(new Runnable() {
                 @Override
                 public void run() {
                        txtview.setText("some value");
                        edittext.setText("some new value");
                 }
                 });
                }catch (Exception e) {
                      //print the error here
                }
          }
     }).start();
    }

4、Message, MessageQueue, Looper

![Image for post][Image for post 1]

![Image for post][Image for post 2]

5、

Handler handler = new Handler(Looper.getMainLooper());
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            // update the ui from here
        }
    },1000);

Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg){
            if(msg.what == 0){
                updateUI();
            }else{
                showError();
            }
        }
    };
    
    Thread thread = new Thread() {
        @Override
        public void run(){
            doSomeWork();
            if(succeed){
                //we can't update the UI from here so we'll signal our handler and it will do it for us.
                handler.sendEmptyMessage(0);
            }else{
                handler.sendEmptyMessage(1);
            }
        }   
    };

![Image for post][Image for post 3]

[Image for post]: /images/20221120/0d8a4f8338284d3794d3555c2c5140c4.png
[Image for post 1]: /images/20221120/0b3ea9bac8634f639e9e191d312b98fe.png
[Image for post 2]: /images/20221120/62dc5533d67a4d3e8c902cdc8d7b0844.png
[Image for post 3]: https://img-blog.csdnimg.cn/img_convert/496529bf8451972736f89849d448581d.png