Android中更新UI的几种方式

た入场券 2022-07-16 09:28 274阅读 0赞

一：runOnUiThread;

二：handler post;

三：handler sendMessage；

四：view post；

示例代码

package com.example.kirito.myapplication;
    
    import android.app.Activity;
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.widget.TextView;
    
    /**
     * Created by kirito on 2016.10.13.
     */
    
    public class Third extends Activity {
        private TextView tv;
        private Handler handler = new Handler(){
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                //更新UI
                tv.setText("update ui");
            }
        };
    
        private Handler handler2 = new Handler();
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.testhandler);
    
            tv = (TextView) findViewById(R.id.tv_handler);
            /*new Thread(){
                @Override
                public void run() {
                    updateUi3();
                }
            }.start();*/
            updateUi2();
        }
    
        private void updateUi1(){
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    //更新UI
                    tv.setText("update ui1");
                }
            });
        }
    
        private void updateUi2(){
            handler2.post(new Runnable() {
                @Override
                public void run() {
                    //更新UI
                    tv.setText("update ui2---" + Thread.currentThread());
                }
            });
        }
        private void updateUi3(){
            handler.sendEmptyMessage(1);
        }
        private void updateUi4(){
            tv.post(new Runnable() {
                @Override
                public void run() {
                    tv.setText("update ui4---" + Thread.currentThread());
                }
            });
        }
    }

五：Android里检测更新的UI操作，需要通过ViewRootImpl，而它的初始化在onresume方法里，当没有调用onresume方法的时候，即使在其他线程里更新UI也不会报错。