1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 2     xmlns:tools="http://schemas.android.com/tools" 3     android:layout_width="match_parent" 4     android:layout_height="match_parent" 5     android:paddingBottom="@dimen/activity_vertical_margin" 6     android:paddingLeft="@dimen/activity_horizontal_margin" 7     android:paddingRight="@dimen/activity_horizontal_margin" 8     android:paddingTop="@dimen/activity_vertical_margin" 9     tools:context="com.example.android_handler.MainActivity" >10 11     <TextView12         android:id="@+id/textview"13         android:layout_width="wrap_content"14         android:layout_height="wrap_content"15         android:text="@string/hello_world" />16 17 </RelativeLayout>

 1 package com.example.android_handler; 2  3 import android.app.Activity; 4 import android.os.Bundle; 5 import android.os.Handler; 6 import android.os.Message; 7 import android.widget.TextView; 8  9 public class MainActivity extends Activity {10     private TextView textview = null;11     private Handler handler = new Handler(){12         public void handleMessage(android.os.Message msg) {13             textview.setText("" +msg.obj);14         };15     };16     @Override17     protected void onCreate(Bundle savedInstanceState) {18         super.onCreate(savedInstanceState);19         setContentView(R.layout.activity_main);20         textview = (TextView) findViewById(R.id.textview);21         new Thread(){22             public void run() {23                 //这个方法可以回收系统中已经存在的message24                 Message message = Message.obtain();25                 /*26                  * 这个也是27                  * Message message = handler.obtainMessage28                  */29                 30                 31                 //obj可以用于传递多种对象32                 message.obj = "123";33                 handler.sendMessage(message);34             };35         }.start();36     }37 }

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2     xmlns:tools="http://schemas.android.com/tools" 3     android:layout_width="match_parent" 4     android:layout_height="match_parent" 5     android:orientation="vertical" 6     tools:context="com.example.android_handler1.MainActivity" > 7     <ImageView  8        android:id="@+id/imageview" 9         android:layout_width="wrap_content"10         android:layout_height="wrap_content"11         />12     <Button 13         android:id="@+id/button"14         android:layout_width="match_parent"15         android:layout_height="wrap_content"16         android:text="@string/button_string"17         />18 19 </LinearLayout>

 1 package com.example.android_handler1; 2  3 import android.app.Activity; 4 import android.os.Bundle; 5 import android.os.Handler; 6 import android.util.Log; 7 import android.view.View; 8 import android.view.View.OnClickListener; 9 import android.widget.Button;10 import android.widget.ImageView;11 12 public class MainActivity extends Activity implements OnClickListener {13     private Handler handler = new Handler();14     private ImageView imageview = null;15     private MyRunnable runnable = new MyRunnable();16     private Button button = null;17     //创建图片数组18     private int images[]={R.drawable.image1, R.drawable.image2,R.drawable.image3};19     //创建一个索引 用于记录当前图片的下标20     private int index = 0;21     @Override22     protected void onCreate(Bundle savedInstanceState) {23         super.onCreate(savedInstanceState);24         setContentView(R.layout.activity_main);25         imageview = (ImageView) findViewById(R.id.imageview);26         button = (Button) findViewById(R.id.button);27         button.setOnClickListener(this);28         new Thread(){29             public void run() {30                 //第一个参数是传入一个Runnable的对象31                 //第二个参数表示的意思是每张图片显示的时间32                 handler.postDelayed(runnable, 1000);33             };34         }.start();35         36         37     }38     //创建一个MYRunnable类， 用于操作imagevie上的图片39     class MyRunnable implements Runnable40     {41 42         public void run() {43             index++;44             index = index % 3;45             imageview.setImageResource(images[index]);46             handler.postDelayed(runnable, 1000);47         }48         49     }50     public void onClick(View v) {51         //利用handler移除runnable，实现停止图片的轮播52         handler.removeCallbacks(runnable);53         54     }55 }