第一行代码android多线程编程

Posted 2021-11-09 iiiLISA

今天写代码的时候，发现书里的Handler构造函数已经过时了。
小白查资料

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    private TextView mText;
    public static final int UPDATE_TEXT=1;
    //定义一个整型常量，用于表示Handler中某个动作

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

        mText = (TextView) findViewById(R.id.text);
        Button changeText = (Button) findViewById(R.id.change_text);
        changeText.setOnClickListener( this);
    }


    //Handler静态内部类
    private static class MyHandler extends Handler {
        //弱引用
        WeakReference<MainActivity> weakReference;
        public MyHandler(MainActivity activity) {
            weakReference = new WeakReference<MainActivity>(activity);
        }
        @Override
        public void handleMessage(Message msg) {
            MainActivity activity = weakReference.get();
            if (activity != null) {
                activity.mText.setText("很高兴认识你");
            }
        }
    }

    private MyHandler handler = new MyHandler(this);



    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.change_text:
                //开启一个子线程更新UI
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        Message message=new Message();
                        message.what=UPDATE_TEXT;
                        handler.sendMessage(message);
                        //将Message对象发出去
                    }
                }).start();
                break;
            default:
                break;
        }
    }
}