ViewPager滑动--RadioButton标识滑动到第几页

//下面我们举一个三张导航页面的例子 我们先看看布局文件 贯穿整个页面的是ViewPager 上面还有三个小圆点使用的是RadioButton

<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=".MainActivity" >

    <android.support.v4.view.ViewPager  android:id="@+id/vp" android:layout_width="match_parent" android:layout_height="match_parent" ></android.support.v4.view.ViewPager>

     <RadioGroup  android:id="@+id/myradiogroup" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignBottom="@+id/vp" android:layout_centerHorizontal="true" android:layout_marginBottom="40dp" android:orientation="horizontal" >

        <RadioButton  android:id="@+id/radio_btn1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:checked="true" />

        <RadioButton  android:id="@+id/radio_btn2" android:layout_width="wrap_content" android:layout_height="wrap_content" />
        <RadioButton  android:id="@+id/radio_btn3" android:layout_width="wrap_content" android:layout_height="wrap_content" />
    </RadioGroup>

</RelativeLayout>

在主类中实现代码

import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.widget.ImageView;
import android.widget.RadioButton;

public class MainActivity extends Activity implements OnPageChangeListener{
    private ViewPager vPager;//viewpager
    private List<View> list;//加载三张图片的集合
    private RadioButton r1,r2,r3;//三个radioButton的按钮
    private int[] image={R.drawable.aaa,R.drawable.bbb,R.drawable.ccc};//三个图片的数组
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //初始化数据 主要是加载三张图片和获得控件的id
        init();
    }

    private void init() {
    //初始化集合
        list=new ArrayList<View>();
        //遍历数组的长度 取出图片设置给每一次实例化的ImageView
        for (int i = 0; i < image.length; i++) {
            ImageView imageView=new ImageView(MainActivity.this);
            imageView.setImageResource(image[i]);
            list.add(imageView);
        }

        vPager=(ViewPager) findViewById(R.id.vp);
        r1=(RadioButton) findViewById(R.id.radio_btn1);
        r2=(RadioButton) findViewById(R.id.radio_btn2);
        r3=(RadioButton) findViewById(R.id.radio_btn3);
        vPager.setAdapter(adapter);
        //为页面的滑动设置监听
        vPager.setOnPageChangeListener(this);
    }
//添加 ViewPager适配器
    PagerAdapter adapter=new PagerAdapter() {

        public Object instantiateItem(android.view.ViewGroup container, int position) {
            container.addView(list.get(position));
            return list.get(position);
        };

        @Override
        public boolean isViewFromObject(View arg0, Object arg1) {
            return arg0==arg1;
        }

        @Override
        public int getCount() {
            return list.size();
        }

        public void destroyItem(android.view.ViewGroup container, int position, Object object) {
            container.removeView(list.get(position));
        };
    };
    //实现viewPager页面滑动监听
    @Override
    public void onPageScrollStateChanged(int arg0) {

    }
    @Override
    public void onPageScrolled(int arg0, float arg1, int arg2) {

    }
    //设置页面滑动后的效果
    @Override
    public void onPageSelected(int arg0) {
        switch (arg0) {
        case 0:
            r1.setChecked(true);
            r2.setChecked(false);
            r3.setChecked(false);
            break;
        case 1:
            r1.setChecked(false);
            r2.setChecked(true);
            r3.setChecked(false);
            break;
        case 2:
            r1.setChecked(false);
            r2.setChecked(false);
            r3.setChecked(true);
            break;
        default:
            break;
        }

    }
}

上述代码实现的效果如下展示