ViewPager2+Fragment联动

主Activity

package com.chengzis.nextstage;

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

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

import com.chengzis.nextstage.adapter.FragmentAdapter;
import com.chengzis.nextstage.fragment.ViewPager2Fragment1;

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

/**
 * ViewPager2+Fragment联动
 * 1.先写全屏 (1.fragment  adapter extends )
 * <p>
 * 2.在写下面的tab
 */

/**
 * 知识点；
 * FragmentManager getSupportFragmentManager()
 *
 * @author 83765
 */
public class ViewPager2Fragment extends AppCompatActivity implements View.OnClickListener {
    private LinearLayout lv1, lv2, lv3, lv4;
    private ImageView iv1, iv2, iv3, iv4;
    private ViewPager2 vp2;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_pager2_fragment);

        initPager();
        initTabView();


    }


    private void initTabView() {
        lv1 = findViewById(R.id.Lv_1);
        lv2 = findViewById(R.id.Lv_2);
        lv3 = findViewById(R.id.Lv_3);
        lv4 = findViewById(R.id.Lv_4);

        lv1.setOnClickListener(this);
        lv2.setOnClickListener(this);
        lv3.setOnClickListener(this);
        lv4.setOnClickListener(this);

        iv1 = findViewById(R.id.iv_1);
        iv2 = findViewById(R.id.iv_2);
        iv3 = findViewById(R.id.iv_3);
        iv4 = findViewById(R.id.iv_4);


    }

    private void initPager() {
        vp2 = findViewById(R.id.vp2);
        ViewPager2Fragment1 fragment1 = new ViewPager2Fragment1();
        List<Fragment> fragmentList = new ArrayList<>();
        fragmentList.add(ViewPager2Fragment1.newInstance("微信"));
        fragmentList.add(ViewPager2Fragment1.newInstance("通讯录"));
        fragmentList.add(ViewPager2Fragment1.newInstance("发现"));
        fragmentList.add(ViewPager2Fragment1.newInstance("我"));


        FragmentAdapter fragmentAdapter = new FragmentAdapter(getSupportFragmentManager(), getLifecycle(), fragmentList);
        vp2.setAdapter(fragmentAdapter);
        /**
         * ViewPager2监听
         *
         */
        vp2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            //页面滚动
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                super.onPageScrolled(position, positionOffset, positionOffsetPixels);


            }

            @Override
            public void onPageSelected(int position) {
                super.onPageSelected(position);
                changeTab(position);
            }
        });
    }

    private void changeTab(int position) {

        switch (position) {

            case R.id.Lv_1:
                vp2.setCurrentItem(0);

            case 0:
                iv1.setSelected(true);
                iv2.setSelected(false);
                iv3.setSelected(false);
                iv4.setSelected(false);

                break;

            case R.id.Lv_2:
                vp2.setCurrentItem(1);
            case 1:
                iv1.setSelected(false);
                iv2.setSelected(true);
                iv3.setSelected(false);
                iv4.setSelected(false);

                break;
            case R.id.Lv_3:
                vp2.setCurrentItem(2);
            case 2:
                iv1.setSelected(false);
                iv2.setSelected(false);
                iv3.setSelected(true);
                iv4.setSelected(false);

                break;
            case R.id.Lv_4:
                vp2.setCurrentItem(3);
            case 3:
                iv1.setSelected(false);
                iv2.setSelected(false);
                iv3.setSelected(false);
                iv4.setSelected(true);

                break;
            default:
                break;
        }
    }

    /**
     * 线性布局点击事件
     *
     * @param v
     */
    @Override
    public void onClick(View v) {
        changeTab(v.getId());
    }


}

主xml

<?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:orientation="vertical"
    android:layout_height="match_parent">

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/vp2"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"/>

    <include layout="@layout/tab_item"/>




</LinearLayout>

adpter

package com.chengzis.nextstage.adapter;

import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.lifecycle.Lifecycle;
import androidx.viewpager2.adapter.FragmentStateAdapter;

import java.util.List;

/**
 * viewpager2的适配器
 * @author 83765
 */

public class FragmentAdapter extends FragmentStateAdapter {

    List<Fragment> fragments ;

    public FragmentAdapter(@NonNull FragmentManager fragmentManager, @NonNull Lifecycle lifecycle, List<Fragment> fragments) {
        super(fragmentManager, lifecycle);
        this.fragments = fragments;
    }


    @NonNull
    @Override
    public Fragment createFragment(int position) {
        return fragments.get(position);
    }

    @Override
    public int getItemCount() {
        return fragments.size();
    }
}

fragment

package com.chengzis.nextstage.fragment;

import android.os.Bundle;

import androidx.fragment.app.Fragment;

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

import com.chengzis.nextstage.R;


/**
 * @author 83765
 */
public class ViewPager2Fragment1 extends Fragment {


    private static final String ARG_PARAM1 = "param1";


    private String mParam1;
    private View root;


    public ViewPager2Fragment1() {

    }


    public static ViewPager2Fragment1 newInstance(String param1) {
        ViewPager2Fragment1 fragment = new ViewPager2Fragment1();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);

        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        if(root==null){
            root = inflater.inflate(R.layout.fragment_view_pager2_, container, false);
            TextView tv = root.findViewById(R.id.tv_change);
            tv.setText(mParam1);

        }

        return root;
    }
}

tab_item

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <LinearLayout
        android:id="@+id/Lv_1"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/iv_1"
            android:src="@drawable/tab_weixiin"
            android:layout_width="40dp"
            android:layout_height="40dp" />
        <TextView
            android:text="微信"
            android:gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>


    </LinearLayout>

    <LinearLayout
        android:id="@+id/Lv_2"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/iv_2"
            android:src="@drawable/tab_weixiin"
            android:layout_width="40dp"
            android:layout_height="40dp" />
        <TextView
            android:text="通讯录"
            android:gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>


    </LinearLayout>

    <LinearLayout
        android:id="@+id/Lv_3"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/iv_3"
            android:src="@drawable/tab_weixiin"
            android:layout_width="40dp"
            android:layout_height="40dp" />
        <TextView
            android:text="发现"
            android:gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>


    </LinearLayout>


    <LinearLayout
        android:id="@+id/Lv_4"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/iv_4"
            android:src="@drawable/tab_weixiin"
            android:layout_width="40dp"
            android:layout_height="40dp" />
        <TextView
            android:text="我"
            android:gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>


    </LinearLayout>





</LinearLayout>

原文链接：https://blog.csdn.net/tzztzz01/article/details/126594960