轮播图

xml界面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <android.support.v4.view.ViewPager
        android:layout_width="match_parent"
        android:layout_height="300dp"
        android:layout_gravity="center_horizontal"
        android:id="@+id/view_pager"
        />
    <RadioGroup
        android:layout_marginTop="15dp"
        android:id="@+id/rg"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        >
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center" />
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center" />
        <RadioButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center" />
    </RadioGroup>
</LinearLayout>

main界面

 private ViewPager viewPager;
    private RadioGroup radioGroup;
    private int[] str={R.drawable.a1,R.drawable.ada,R.drawable.asa};
    ArrayList<ImageView> list=new ArrayList<>();
     @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewPager=findViewById(R.id.view_pager);
        //手指滑动时就不在自动轮播啦
        radioGroup=findViewById(R.id.rg);
        for (int i=0;i<str.length;i++){
            ImageView imageView=new ImageView(MainActivity.this);
            imageView.setBackgroundResource(str[i]);
            list.add(imageView);
        }
        viewPager.setAdapter(new MyAdapter(list,MainActivity.this));
        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int i, float v, int i1) {

            }

            @Override
            public void onPageSelected(int i) {

            }

            @Override
            public void onPageScrollStateChanged(int i) {

            }
        });
        handler.sendEmptyMessageDelayed(0,2000);
    }

hander

Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what){
                case 0:
                    int currentitem=viewPager.getCurrentItem();
                    viewPager.setCurrentItem(currentitem+1);
                    radioGroup.check(currentitem%list.size()+1);
                    handler.sendEmptyMessageDelayed(0,2000);
                    break;
            }
        }
    };

adapter

package com.example.demo6;

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import java.util.ArrayList;

public class MyAdapter extends PagerAdapter{
    private ArrayList<ImageView> list;
    private Context context;

    public MyAdapter(ArrayList<ImageView> list, Context context) {
        this.list = list;
        this.context = context;
    }

    @Override
    public int getCount() {
        return Integer.MAX_VALUE;
    }

    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {
        return view==o;
    }

    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) {
        ImageView imageView=list.get(position%list.size());
        if (imageView.getParent()!=null){
            ((ViewPager)imageView.getParent()).removeView(imageView);
        }
        ((ViewPager)container).addView((View) imageView,0);
        return imageView;
    }

    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
//        super.destroyItem(container, position, object);
    }
}