Android图像切换器imageSwitcher的实例应用

package com.example.su446;
 
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.Button;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher.ViewFactory;
 
public class MainActivity extends Activity {
 //声明并初始化一个保存要显示图像id的数组
 private int[]imageId={R.drawable.img01,R.drawable.img02,R.drawable.img03,R.drawable.img04,
 R.drawable.img05,R.drawable.img06,R.drawable.img07,R.drawable.img08,R.drawable.img09};
 private int index=0;//显示图像的索引
 private ImageSwitcher imageSwitcher;//声明一个图像切换器对象
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 imageSwitcher=(ImageSwitcher)findViewById(R.id.imageSwitcher1);
 //设置淡入动画
 imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));
 //设置淡出动画
 imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));
 imageSwitcher.setFactory(new ViewFactory() {
 
 @Override
 public View makeView() {
 // TODO Auto-generated method stub
 ImageView imageView=new ImageView(MainActivity.this);
 imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
 imageView.setLayoutParams(new ImageSwitcher.LayoutParams(
  LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
 return imageView;
 }
 });
 imageSwitcher.setImageResource(imageId[index]);//显示默认的图片
 Button up=(Button)findViewById(R.id.button1);
 Button down=(Button)findViewById(R.id.button2);
 up.setOnClickListener(new OnClickListener() {//为上一张添加事件监听器
 
 @Override
 public void onClick(View v) {
 // TODO Auto-generated method stub
 if(index>0)
  index--;
 else
  index=imageId.length-1;
 imageSwitcher.setImageResource(imageId[index]);
 }
 });
 down.setOnClickListener(new OnClickListener() {//为下一张添加事件监听器
 
 @Override
 public void onClick(View v) {
 // TODO Auto-generated method stub
 if(index