viewPager2 基本使用

1 增加依赖

dependencies {
    implementation "androidx.viewpager2:viewpager2:1.0.0"
    implementation 'androidx.recyclerview:recyclerview:1.1.0'
}

2.添加xml里面的viewPager2

<?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">
    <androidx.viewpager2.widget.ViewPager2
        android:background="#ccc"
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="200sp"/>
</LinearLayout>

3.使用 1.自定义 new ViewPagerAdapter() 2.viewPager.setAdapter

package com.example.viewpagerapplication;

import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager2.widget.ViewPager2;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ViewPager2 viewPager = findViewById(R.id.viewpager);
        ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter();
        viewPager.setAdapter(viewPagerAdapter);
    }
}

文件ViewPagerAdapter.java 1.设置行数才能显示，2.加载xml需要注意

package com.example.viewpagerapplication;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

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

// 3 RecyclerView.Adapter(后面要跟着一个范型)
public class ViewPagerAdapter extends RecyclerView.Adapter<ViewPagerAdapter.ViewPagerViewHolder> {
    private List<String> titles = new ArrayList<>();
    public  ViewPagerAdapter(){ // 初始化数据函数
        titles.add("1");
        titles.add("21");
        titles.add("31");
        titles.add("41");
        titles.add("51");
        titles.add("61");
        titles.add("71");
        titles.add("81");
        titles.add("91");
        titles.add("101");
    }
    @NonNull
    @Override
    public ViewPagerAdapter.ViewPagerViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        // 2.1ViewPagerViewHolder 修改下面的内部类 (加载 ，解析xml的操作)
        return new ViewPagerAdapter.ViewPagerViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_pager,parent,false));
    }

    @Override
    public void onBindViewHolder(@NonNull ViewPagerViewHolder holder, int position) {
        // 2.ViewPagerViewHolder 修改下面的内部类
        // 修改数据
        holder.tV.setText(titles.get(position));
    }

    @Override     // 设置10个滚动的数据个数 getItemCount
    public int getItemCount() {
        return 8;
    }
    // 1.建1个内部类
    class ViewPagerViewHolder extends  RecyclerView.ViewHolder {
        TextView tV;
        RelativeLayout relativeLayout;
        public ViewPagerViewHolder(@NonNull View itemView) {
            super(itemView);
            relativeLayout = itemView.findViewById(R.id.container);
            tV = itemView.findViewById(R.id.test1);
        }
    }
}