ViewPager引导页，底部圆点导航

项目列表

首先新建一个class文件，名字为 MyPageAdapter.java

package com.example.smartwee;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.viewpager.widget.PagerAdapter;

import java.util.List;

public class MyPageAdapter extends PagerAdapter {
    private List views;
    private Context context;
    MyPageAdapter(List views,Context context){
        this.context=context;
        this.views=views;
    }
    @Override
    public int getCount() {
        return views.size();
    }

    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
        return view == object;
    }
    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) {
        container.addView(views.get(position));
        return views.get(position);
    }

    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        container.removeView(views.get(position));
    }

}

 创建布局文件，welcome_0,welcome_1welcome_2,welcome_3,welcome_4,

一共五个，代表有五页的引导，可以增加或减少，不过Welcom.java中的代码也需要更改

布局代码都是一样的，这里贴一个，使用scaleType让图片按比例填充，多余的裁剪

新建一个Activity，名字为 Welcome

package com.example.smartwee;

import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;

import java.util.ArrayList;
import java.util.List;

public class Welcome extends AppCompatActivity {

    private ViewPager viewPager;
    private ImageView iv1,iv2,iv3,iv4,iv5;
    private int[] pics={R.layout.welcome_0,R.layout.welcome_1,R.layout.welcome_2,R.layout.welcome_3,R.layout.welcome_4};
    private List views;
    private MyPageAdapter pageAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_welcome);
        //获取控件
        iv1 =findViewById(R.id.iv_1);
        iv2 =findViewById(R.id.iv_2);
        iv3 =findViewById(R.id.iv_3);
        iv4 =findViewById(R.id.iv_4);
        iv5 =findViewById(R.id.iv_5);
        viewPager=findViewById(R.id.viewPager);
        initView();
    }

    private void initView() {
        //初始化圆点，让第一个点为true，其他的关闭
        setDot(true,false,false,false,false);


        if (views == null)
            views = new ArrayList<>();//判断初始化
        for (int i =0;i < pics.length;i++){
            View view = LayoutInflater.from(this).inflate(pics[i],null);
            views.add(view);//将pics中的布局添加至view中
        }
        pageAdapter = new MyPageAdapter(views,this);//MyPageAdapter是开始时创建的名字，可以自己更改
        viewPager.setAdapter(pageAdapter);//设置适配器

        //给viewpage添加监听事件
        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {//position的值代表你翻动到了第几页

                switch (position){
                    case 0:
                        setDot(true,false,false,false,false);
                        break;
                    case 1:
                        setDot(false,true,false,false,false);
                        break;
                    case 2:
                        setDot(false,false,true,false,false);
                        break;
                    case 3:
                        setDot(false,false,false,true,false);
                        break;
                    case 4:
                        setDot(false,false,false,false,true);
                        break;
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    private void setDot(boolean a,boolean b,boolean c,boolean d,boolean e) {
        if (a){
            iv1.setImageResource(R.drawable.btn_select_t_12);
        }else {
            iv1.setImageResource(R.drawable.btn_select_f_12);
        } if (b){
            iv2.setImageResource(R.drawable.btn_select_t_12);
        }else {
            iv2.setImageResource(R.drawable.btn_select_f_12);
        } if (c){
            iv3.setImageResource(R.drawable.btn_select_t_12);
        }else {
            iv3.setImageResource(R.drawable.btn_select_f_12);
        } if (d){
            iv4.setImageResource(R.drawable.btn_select_t_12);
        }else {
            iv4.setImageResource(R.drawable.btn_select_f_12);
        } if (e){
            iv5.setImageResource(R.drawable.btn_select_t_12);
        }else {
            iv5.setImageResource(R.drawable.btn_select_f_12);
        }//图片t_12是一个12像素的绿点，我用ps画的，f_12是白色的
    }

}

 启动前不要忘记在AndroidManifest.xml中更改启动页

启动效果：