package com.shaking.androidthreadtest;

import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
 private static final int UPDATE_TEXT=1;
 private String data;
 private TextView textView;
 
 private Handler handler=new Handler(){
 @Override
 public void handleMessage(Message msg) {
  switch (msg.what){
  case UPDATE_TEXT:
   textView.setText(data);
  }
 }
 };

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main_layout);
 Button button=findViewById(R.id.button);
 textView=findViewById(R.id.text_view);
 button.setOnClickListener(this);
 }

 @Override
 public void onClick(View view) {
 new Thread(new Runnable() {
  @Override
  public void run() {
  //假设此处进行了耗时操作，最终得到结果字符串data
  data="Nice to meet you";
  Message message=new Message();
  message.what=UPDATE_TEXT;
  handler.sendMessage(message);
  }
 }).start();
 }
}

private static class MyHandler extends Handler{
 @Override
 public void handleMessage(Message msg) {
   
  
 }
 }

package com.shaking.androidthreadtest;

import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.lang.ref.WeakReference;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
 private static final int UPDATE_TEXT=1;
 private String data;
 private TextView textView;

 private static class MyHandler extends Handler{
 //使该内部类持有对外部类的弱引用
 private WeakReference<MainActivity> weakReference;
 //构造器中完成弱引用初始化
 MyHandler(MainActivity activity){
  weakReference=new WeakReference<>(activity);
 }
 @Override
 public void handleMessage(Message msg) {
  //通过弱引用的get()方法获得外部类对象的引用
  MainActivity activity=weakReference.get();
  activity.textView.setText(activity.data);
 }
 }
 //创建Handler对象
 private MyHandler handler=new MyHandler(this);
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main_layout);
 Button button=findViewById(R.id.button);
 textView=findViewById(R.id.text_view);
 button.setOnClickListener(this);
 }

 @Override
 public void onClick(View view) {
 new Thread(new Runnable() {
  @Override
  public void run() {
  //假设此处进行了耗时操作，最终得到结果字符串data
  data="Nice to meet you";
  Message message=new Message();
  message.what=UPDATE_TEXT;
  handler.sendMessage(message);
  }
 }).start();
 }
}