package com.example.uirefresh; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.ScrollView; import android.widget.TextView; public class MainActivity extends Activity implements android.view.View.OnClickListener{ private Button btnExit; private TextView text; private ScrollView scroll; private boolean bool = true; @Override protected void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);     btnExit = (Button) findViewById(R.id.exit);     text    = (TextView) findViewById(R.id.text);     scroll  = (ScrollView) findViewById(R.id.scroll);     btnExit.setOnClickListener(this);     //在主线程main中开一子线程来刷新局部的ScrollView     new Thread(new RefreshThread()).start();    } @Override public void onClick(View v) {     switch(v.getId()) {     case R.id.exit :         finish();         break;     } }   public class RefreshThread implements Runnable{     @Override     public void run() {         while(bool) {             try {                 Thread.sleep(5000);//每五秒刷新一次             } catch (InterruptedException e) {                 e.printStackTrace();             }             synchronized (this) {                                 //用post方法刷新                 text.post(new Runnable() {                                      @Override                     public void run() {                         text.append("Hello World...n");                     }                 });             }         }     }       }   @Override protected void onDestroy(){     super.onDestroy();     bool = false; } }