Android ViewPager实现左右滑动翻页效果

package com.example.demo;  import java.util.ArrayList;  import android.app.Activity; import android.content.Context; import android.os.Bundle; import android.support.v4.view.PagerAdapter; import android.support.v4.view.ViewPager; import android.view.View; import android.view.ViewGroup; import android.widget.TextView;   public class MainActivity extends Activity {   @Override  protected void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   setContentView(R.layout.activity_main);      ViewPager mViewPager=(ViewPager) findViewById(R.id.viewPager);      PagerAdapter mPagerAdapter=new MyPagerAdapter(this);      mViewPager.setAdapter(mPagerAdapter);  }    private class MyPagerAdapter extends PagerAdapter{    private Context context;      private ArrayList<TextView> views;      public MyPagerAdapter(Context context){    this.context=context;    views=new ArrayList<TextView>();    for(int i=0;i<30;i++){     TextView tv=new TextView(context);     tv.setText(""+i);     views.add(tv);    }   }      @Override   public int getCount() {    return views.size();   }      @Override   public void destroyItem(ViewGroup container, int position,Object object) {    container.removeView(views.get(position));   }      @Override   public View instantiateItem(ViewGroup container, int position){     ((ViewGroup) container).addView(views.get(position));        return views.get(position);   }    @Override   public boolean isViewFromObject(View arg0, Object arg1) {    return arg0==arg1;   }  } } 

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools"  android:layout_width="match_parent"  android:layout_height="match_parent"  tools:context="com.example.demo.MainActivity" >   <android.support.v4.view.ViewPager   android:id="@+id/viewPager"   android:layout_width="match_parent"  android:layout_height="match_parent"/> </RelativeLayout>