android应用中怎么对UI进行异步更新

发布时间：2020-12-05 15:55:15 作者：Leah
来源：亿速云阅读：150

本篇文章给大家分享的是有关android应用中怎么对UI进行异步更新，小编觉得挺实用的，因此分享给大家学习，希望大家阅读完这篇文章后可以有所收获，话不多说，跟着小编一起来看看吧。

1.使用Handler消息传递机制

package com.example.runonuithreadtest;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;

public class MainActivity extends Activity {
 
 private TextView tv;
 
 Handler handler = new Handler()
 {
  public void handleMessage(android.os.Message msg) {
   if(msg.what==0x123)
   {
    tv.setText("更新后的TextView");
   }
  };
 };
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  tv = (TextView) findViewById(R.id.tv);
  new MyThread().start();
 }
 class MyThread extends Thread
 {
  @Override
  public void run() {
   //延迟两秒更新
   try {
    Thread.sleep(2000);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   handler.sendEmptyMessage(0x123);
  }
 }
}

2. 使用AsyncTask异步任务

注：更新UI的操作只能在onPostExecute(String result)方法中。

package com.example.runonuithreadtest;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity {
 
 private TextView tv;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  tv = (TextView) findViewById(R.id.tv);
  new Yibu().execute();
 }
 class Yibu extends AsyncTask<String, String, String>
 {

  @Override
  protected String doInBackground(String... params) {
   try {
    Thread.sleep(2000);
   } catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   return null;
  }
  @Override
  protected void onPostExecute(String result) {
   // TODO Auto-generated method stub
   tv.setText("更新后的TextView");
  }
  
 }
}

3. 使用runOnUiThread(action)方法

package com.example.runonuithreadtest;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity {
 
 private TextView tv;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  tv = (TextView) findViewById(R.id.tv);
  new MyThread().start();
 }
 class MyThread extends Thread
 {
  @Override
  public void run() {
   runOnUiThread(new Runnable() {
    
    @Override
    public void run() {
     // TODO Auto-generated method stub
      try {
       //延迟两秒更新
       Thread.sleep(2000);
      } catch (InterruptedException e) {
       e.printStackTrace();
      }
      tv.setText("更新后的TextView");
    }
   });
  }
 }
}

4. 使用Handler的post(Runnabel r)方法

package com.example.runonuithreadtest;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;

public class MainActivity extends Activity {
 
 private TextView tv;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  tv = (TextView) findViewById(R.id.tv);
  Handler handler = new Handler();
  handler.post(new Runnable(){
   @Override
   public void run() {
    try {
     //延迟两秒更新
     Thread.sleep(2000);
    } catch (InterruptedException e) {
     e.printStackTrace();
    }
    tv.setText("更新后的TextView");
   }

以上就是android应用中怎么对UI进行异步更新，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注亿速云行业资讯频道。

android应用中怎么对UI进行异步更新

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