Android开发之ViewPager+Fragment

<android.support.v4.view.ViewPager 
     android:id="@+id/viewpager"     
     android:layout_width="wrap_content"    
     android:layout_height="wrap_content"   
     android:layout_gravity="center" >  
 </android.support.v4.view.ViewPager>

Fragment1 f1 = new Fragment1();
Fragment2 f2 = new Fragment2();
Fragment3 f3 = new Fragment3();
fragmentContainter = new ArrayList<Fragment>();    
fragmentContainter.add(f1);
fragmentContainter.add(f2);
fragmentContainter.add(f3);

pager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager())
        {

            @Override
            public int getCount()
            {

                return fragmentContainter.size();
            }

            @Override
            public android.support.v4.app.Fragment getItem(int arg0)
            {
                return fragmentContainter.get(arg0);
            }
        });