the usage of android viewpage

package com.vp.photo;

import java.util.ArrayList;
import java.util.List;


import android.app.Activity;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.Window;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;

public class ViewpageActivity extends Activity {
    /** Called when the activity is first created. */
	private ViewPager viewpage;
	private LayoutInflater mInflater;
	private List<View> mListViews;
    @Override
    public void onCreate(Bundle savedInstanceState) {
    	requestWindowFeature(Window.FEATURE_NO_TITLE);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        viewpage = (ViewPager) findViewById(R.id.veiwpage);
        mInflater = getLayoutInflater();
        
        mListViews= new ArrayList<View>();
        mListViews.add(mInflater.inflate(R.layout.pageview_mn, null));
        mListViews.add(mInflater.inflate(R.layout.pageview_im, null));
        mListViews.add(mInflater.inflate(R.layout.pageview_mm, null));
        mListViews.add(mInflater.inflate(R.layout.pageview_im, null));
        
        
        MyPageAdapter adpater = new MyPageAdapter();
        viewpage.setAdapter(adpater);
    }
    
    
    class MyPageAdapter extends PagerAdapter{

		@Override
		public int getCount() {
			// TODO Auto-generated method stub
			return mListViews.size();
		}

		
		
		@Override
		public void destroyItem(View container, int position, Object object) {
			// TODO Auto-generated method stub
			((ViewPager)container).removeView(mListViews.get(position));
		}



		@Override
		public Object instantiateItem(View container, int position) {
			// TODO Auto-generated method stub
			((ViewPager)container).addView(mListViews.get(position));
			switch(position){
				case 1:
					break;
				case 2:
					Button FX = (Button) container.findViewById(R.id.fx);
					final EditText ET = (EditText) container.findViewById(R.id.username);
					FX.setOnClickListener(new OnClickListener() {
						
						@Override
						public void onClick(View v) {
							// TODO Auto-generated method stub
							Toast.makeText(ViewpageActivity.this, "發現 ^_^ " + ET.getText().toString() , Toast.LENGTH_SHORT).show();
						}
					});
					break;
				case 3:
					ImageView IV = (ImageView) container.findViewById(R.id.pg_image);
					IV.setBackgroundResource(R.drawable.rain_c);
					break;
				case 4:
					break;
			}
			return mListViews.get(position);
		}

		@Override
		public Parcelable saveState() {
			return null;
		}

		@Override
		public boolean isViewFromObject(View view, Object objects) {
			// TODO Auto-generated method stub
			
			return view == (objects);
		}
    	
    }

	 @Override
	 public boolean onKeyDown(int keyCode, KeyEvent event) { 
	    	if(keyCode == KeyEvent.KEYCODE_BACK){
	    		ExitControl.showWarning(this, "Do you want to exit");
	    	}
	    	return super.onKeyDown(keyCode, event);
	}
}