<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

     xmlns:tools="http://schemas.android.com/tools"

     android:layout_width="match_parent"

     android:layout_height="match_parent"

     android:paddingBottom="@dimen/activity_vertical_margin"

     android:paddingLeft="@dimen/activity_horizontal_margin"

     android:paddingRight="@dimen/activity_horizontal_margin"

     android:paddingTop="@dimen/activity_vertical_margin"

     tools:context="com.example.s01_original_e14_simplehandler.MainActivity" >

     <Button

         android:id="@+id/startThread"

         android:layout_width="wrap_content"

         android:layout_height="wrap_content"

         android:text="@string/startThread"/>

      <Button

      android:id="@+id/stopThread"

      android:layout_width="wrap_content"

      android:layout_height="wrap_content"

      android:text="@string/stopThread"

      android:layout_below="@id/startThread"/>

      <TextView

          android:id="@+id/myTextView"

          android:layout_width="wrap_content"

          android:layout_height="wrap_content"

          android:layout_below="@id/stopThread"/>

 </RelativeLayout>

 package com.example.s01_original_e14_simplehandler;

 import android.app.Activity;

 import android.os.Bundle;

 import android.os.Handler;

 import android.view.View;

 import android.view.View.OnClickListener;

 import android.widget.Button;

 import android.widget.TextView;

 public class MainActivity extends Activity {

     private Button startThread = null;

     private Button stopThread = null;

     private TextView myTextView = null;

     @Override

     protected void onCreate(Bundle savedInstanceState) {

         super.onCreate(savedInstanceState);

         setContentView(R.layout.activity_main);

         myTextView = (TextView) findViewById(R.id.myTextView);

         startThread = (Button) findViewById(R.id.startThread);

         stopThread = (Button) findViewById(R.id.stopThread);

         startThread.setOnClickListener(new OnClickListener() {

             @Override

             public void onClick(View v) {

                 handler.post(updateThread);

             }

         });

         stopThread.setOnClickListener(new OnClickListener() {

             @Override

             public void onClick(View v) {

                 handler.removeCallbacks(updateThread);

             }

         });

     }

     Handler handler = new Handler();

     Runnable updateThread = new Runnable() {

         @Override

         public void run() {

             System.out.println("---updateThread");

             myTextView.setText(System.currentTimeMillis()+"");

             handler.postDelayed(updateThread, 2000);

         }

     };

 }