Fragment+ViewPager滑动

package com.qy.glide;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.RadioGroup;

import com.bumptech.glide.Glide;
import com.qy.glide.fragment.Frag01;
import com.qy.glide.fragment.Frag02;
import com.qy.glide.fragment.Frag03;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

private ViewPager pager;
private RadioGroup radioGroup;
private ArrayList<Fragment> list;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
	
	
    pager = findViewById(R.id.vp);
    radioGroup = findViewById(R.id.radioG);
    //页面数据
    list = new ArrayList<>();
    list.add(new Frag01());
    list.add(new Frag02());
    list.add(new Frag03());
    //view pager 适配器
    pager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
        @Override
        public Fragment getItem(int i) {
            return list.get(i);

        }

        @Override
        public int getCount() {
            return list.size();
        }
    });
    ///滑动的时候切换按钮选中状态
    pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int i, float v, int i1) {

        }

        @Override
        public void onPageSelected(int i) {
            radioGroup.check(radioGroup.getChildAt(i).getId());
        }

        @Override
        public void onPageScrollStateChanged(int i) {

        }
    });
    //点击按钮切换
    radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(RadioGroup group, int checkedId) {
            switch (checkedId) {
                case R.id.r1:
                    pager.setCurrentItem(0);
                    break;
                case R.id.r2: 
                    pager.setCurrentItem(1);
                    break;
                case R.id.r3:
                    pager.setCurrentItem(2);
                    break;
            }
        }
    });

}

}