滑动折叠效果

效果展示

布局（main_activity）

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/img"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:background="#B52525"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />


    <androidx.coordinatorlayout.widget.CoordinatorLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/img">

        <com.google.android.material.appbar.AppBarLayout
            android:id="@+id/appBarLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <com.google.android.material.appbar.CollapsingToolbarLayout
                android:id="@+id/collapsingToolbar"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                app:expandedTitleMarginEnd="0dp"
                app:expandedTitleMarginStart="0dp"
                app:expandedTitleMarginTop="?attr/actionBarSize"
                app:layout_scrollFlags="scroll|exitUntilCollapsed">

                <ImageView
                    android:layout_width="match_parent"
                    android:layout_height="200dp"
                    android:scaleType="centerCrop"
                    android:src="@drawable/img2"
                    app:layout_collapseMode="parallax" />

            </com.google.android.material.appbar.CollapsingToolbarLayout>

        </com.google.android.material.appbar.AppBarLayout>

        <androidx.viewpager2.widget.ViewPager2
            android:id="@+id/view_pager"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="horizontal"
            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
    </androidx.coordinatorlayout.widget.CoordinatorLayout>

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tab_layout"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:visibility="gone"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/img"
        app:tabGravity="center"
        app:tabIndicatorColor="#ff678f"
        app:tabIndicatorFullWidth="false"
        app:tabIndicatorHeight="2dp"
        app:tabMode="scrollable"
        app:tabSelectedTextColor="#ff678f"
        app:tabTextColor="#333333"
        app:tabUnboundedRipple="true" />
</androidx.constraintlayout.widget.ConstraintLayout>

activity逻辑

package com.example.viewpager2_test;

import android.content.res.ColorStateList;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.viewpager2.adapter.FragmentStateAdapter;
import androidx.viewpager2.widget.ViewPager2;

import com.google.android.material.appbar.AppBarLayout;
import com.google.android.material.tabs.TabLayout;
import com.google.android.material.tabs.TabLayoutMediator;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private TabLayout tabLayout;
    private ViewPager2 viewPager2;

    private int activeColor = Color.parseColor("#ff678f");
    private int normalColor = Color.parseColor("#666666");

    private int activeSize = 20;
    private int normalSize = 14;

    private ArrayList<Fragment> fragments;
    private TabLayoutMediator mediator;
    private AppBarLayout appBarLayout;

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

        tabLayout = findViewById(R.id.tab_layout);
        viewPager2 = findViewById(R.id.view_pager);
        appBarLayout = findViewById(R.id.appBarLayout);
        appBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
            @Override
            public void onOffsetChanged(AppBarLayout appBarLayout, int i) {
                if (i == 0) {
                    if (tabLayout.getVisibility() == View.VISIBLE) {
                        tabLayout.setVisibility(View.GONE);
                    }
                } else {
                    if (tabLayout.getVisibility() == View.GONE) {
                        tabLayout.setVisibility(View.VISIBLE);
                    }
                }

            }
        });

        final String[] tabs = new String[]{"关注", "推荐", "最新0", "最新1", "最新2", "最新3", "最新4", "最新5", "最新6"};

        //禁用预加载
        viewPager2.setOffscreenPageLimit(ViewPager2.OFFSCREEN_PAGE_LIMIT_DEFAULT);
        //Adapter
        viewPager2.setAdapter(new FragmentStateAdapter(getSupportFragmentManager(), getLifecycle()) {
            @NonNull
            @Override
            public Fragment createFragment(int position) {
                //FragmentStateAdapter内部自己会管理已实例化的fragment对象。
                // 所以不需要考虑复用的问题
                return TestFragment.newInstance(tabs[position]);
            }

            @Override
            public int getItemCount() {
                return tabs.length;
            }
        });
        //viewPager 页面切换监听监听
        viewPager2.registerOnPageChangeCallback(changeCallback);

        mediator = new TabLayoutMediator(tabLayout, viewPager2, new TabLayoutMediator.TabConfigurationStrategy() {
            @Override
            public void onConfigureTab(@NonNull TabLayout.Tab tab, int position) {
                //这里可以自定义TabView
                TextView tabView = new TextView(MainActivity.this);

                int[][] states = new int[2][];
                states[0] = new int[]{android.R.attr.state_selected};
                states[1] = new int[]{};

                int[] colors = new int[]{activeColor, normalColor};
                ColorStateList colorStateList = new ColorStateList(states, colors);
                tabView.setText(tabs[position]);
                tabView.setTextSize(normalSize);
                tabView.setTextColor(colorStateList);

                tab.setCustomView(tabView);
            }
        });
        //要执行这一句才是真正将两者绑定起来
        mediator.attach();
    }

    private ViewPager2.OnPageChangeCallback changeCallback = new ViewPager2.OnPageChangeCallback() {
        @Override
        public void onPageSelected(int position) {
            //可以来设置选中时tab的大小
            int tabCount = tabLayout.getTabCount();
            for (int i = 0; i < tabCount; i++) {
                TabLayout.Tab tab = tabLayout.getTabAt(i);
                TextView tabView = (TextView) tab.getCustomView();
                if (tab.getPosition() == position) {
                    tabView.setTextSize(activeSize);
                    tabView.setTypeface(Typeface.DEFAULT_BOLD);
                } else {
                    tabView.setTextSize(normalSize);
                    tabView.setTypeface(Typeface.DEFAULT);
                }
            }
        }
    };

    @Override
    protected void onDestroy() {
        mediator.detach();
        viewPager2.unregisterOnPageChangeCallback(changeCallback);
        super.onDestroy();
    }
}

Fragment内部使用RecyclerView

效果如下

传不上去。。。。