Android 이미지 전환기 구현

private int[] imageId = new int[] { 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 };   //                ID   
private int index = 0;           //          
private ImageSwitcher imageSwitcher;    //            
 
 
 imageSwitcher = (ImageSwitcher) findViewById(R.id.imageSwitcher1); //        
      //       
 imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
  android.R.anim.fade_in)); //       
 imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,
  android.R.anim.fade_out)); //       
 imageSwitcher.setFactory(new ViewFactory() {
 
 @Override
 public View makeView() {
  ImageView imageView = new ImageView(MainActivity.this); //      ImageView    
  imageView.setScaleType(ImageView.ScaleType.FIT_CENTER); //              
  imageView.setLayoutParams(new ImageSwitcher.LayoutParams(
   LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
  return imageView;                    //   imageView  
 }
 
 });
 imageSwitcher.setImageResource(imageId[index]);  //         
     Button up = (Button) findViewById(R.id.btn1);  //   “   ”  
 Button down = (Button) findViewById(R.id.btn2); //   “   ”  
 up.setOnClickListener(new OnClickListener() {
  @Override
 public void onClick(View v) {
   if (index > 0) {
   index--;
  } else {
   index = imageId.length - 1;
  }
  imageSwitcher.setImageResource(imageId[index]); //       
 }
 });
 down.setOnClickListener(new OnClickListener() {
  @Override
 public void onClick(View v) {
  if (index < imageId.length - 1) {
  index++;
  } else {
  index = 0;
  }
  imageSwitcher.setImageResource(imageId[index]); //       
 }
 }); 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="horizontal"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:id="@+id/llayout"
  android:gravity="center"
  >
  <Button 
   android:text="   " 
   android:id="@+id/btn1" 
   android:layout_width="wrap_content" 
   android:layout_height="wrap_content"/>
 
 <ImageSwitcher
 android:id="@+id/imageSwitcher1" 
 android:layout_gravity="center"
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content"/>
 
  <Button 
   android:text="   " 
   android:id="@+id/btn2" 
   android:layout_width="wrap_content" 
   android:layout_height="wrap_content"/>
</LinearLayout>