为什么我给ImageSwitcher注册了监听事件，当我点击该图片的时候为什么模拟器说程序失败，强制退出？

public class ImageswitchActivity extends Activity implements ViewFactory, OnItemSelectedListener {
    /** Called when the activity is first created. */
ImageSwitcher imageswitch;
Gallery gallery;
OnClickListener listener0=null;
// AlertDialog alert=null;

    private Integer[] mThumbIds ={R.drawable.mn,R.drawable.gril,R.drawable.beatifull,R.drawable.img};
    private Integer[] mImageIds  ={R.drawable.mn,R.drawable.gril,R.drawable.beatifull,R.drawable.img};
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.main);
        setTitle("imageshow");
        imageswitch=(ImageSwitcher)findViewById(R.id.imageswitch);
        imageswitch.setFactory(this);
        imageswitch.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));
        imageswitch.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));
        gallery = (Gallery) findViewById(R.id.gallery);
        gallery.setAdapter(new ImageAdapter(this));
        gallery.setOnItemSelectedListener(this);
       listener0=new OnClickListener(){
         public void onClick(View v)
         { 
         new AlertDialog.Builder(v.getContext())
               .setView(v)
               .setPositiveButton("确定", new DialogInterface.OnClickListener(){   
                            public void onClick(DialogInterface dialog, int which) {   
                   dialog.dismiss();   
                 }}) 
               .show();
         }
        };
       imageswitch.setOnClickListener(listener0);
      
    }
  public View makeView() {
     ImageView i = new ImageView(this);
     i.setBackgroundColor(0xFF000000);
     i.setScaleType(ImageView.ScaleType.FIT_CENTER);
     i.setLayoutParams(new ImageSwitcher.LayoutParams(
       LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
     return i;
    }public class ImageAdapter extends BaseAdapter {
  public ImageAdapter(Context c) {
   mContext = c;
  }   public int getCount() {
   return mThumbIds.length;
  }   public Object getItem(int position) {
   return position;
  }   public long getItemId(int position) {
   return position;
  }   public View getView(int position, View convertView, ViewGroup parent) {
   ImageView i = new ImageView(mContext);    i.setImageResource(mThumbIds[position]);
   i.setAdjustViewBounds(true);
   i.setLayoutParams(new Gallery.LayoutParams(
     LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
   i.setBackgroundResource(R.drawable.star);
   return i;
  }   private Context mContext;  }public void onItemSelected(AdapterView<?> parent, View view, int position,
  long id) {
imageswitch.setImageResource(mImageIds[position]);

}  
public void onNothingSelected(AdapterView<?> parent) {
 // TODO Auto-generated method stub}
}