ViewPager2+Fragment

review

1.Fragment The birth of

Fragment It can be regarded as a small Activity, But do you know Fragment What is the cause of this ？

Fragment, Chinese translation is debris ,Fragments In activity Activity Change the layout configuration for different screen sizes （ A small screen may display one clip at a time , And the big screen can show two or more ）

Use Fragment It is equivalent to one layout adapting to two devices

To make a Activity Simple configuration interface

A simple and efficient , Easy to maintain .

What is? Fragment

​ Fragment Must parasitize on a host Activity in , Equivalent to a son Activity

**Activity Send a message to Fragment

Native Bundle

2. How to hide the title bar

private void hideBar(){
    
    ActionBar actionBar = getSupportActionBar();
    if(actionBar!=null){
    
        actionBar.hide();
	}
}

ViewPager2

Introduce

Allow pages with data to be flipped left and right

Analysis of the source code

ViewPager2 Although it is inherited from ViewGroup, But actually it is Yes RecyclerView Encapsulation

Let's take a look first ViewPager2 The basic source code , A focus on initialize Method inside ：

private void initialize(Context context, AttributeSet attrs) {
    
        //  initialization RecyclerView
        mRecyclerView = new RecyclerViewImpl(context);
        mRecyclerView.setId(ViewCompat.generateViewId());
        //  initialization LayoutManager
        mLayoutManager = new LinearLayoutManagerImpl(context);
        mRecyclerView.setLayoutManager(mLayoutManager);
        setOrientation(context, attrs);  

		mRecyclerView.setLayoutParams(
            new ViewGroup.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
        mRecyclerView.addOnChildAttachStateChangeListener(enforceChildFillListener());

        //  Create the object of the sliding event converter 
        mScrollEventAdapter = new ScrollEventAdapter(mLayoutManager);
        //  Create objects that simulate drag events 
        mFakeDragger = new FakeDrag(this, mScrollEventAdapter, mRecyclerView);
        //  establish PagerSnapHelper object , Used to achieve the basic effect of page switching 
        mPagerSnapHelper = new PagerSnapHelperImpl();
        mPagerSnapHelper.attachToRecyclerView(mRecyclerView);

        mRecyclerView.addOnScrollListener(mScrollEventAdapter);
        // ······
}

stay initialize Method inside , Primary initialization RecyclerView The basic configuration and basic components of include ：

1. to RecyclerView Set sliding listening events （ScrollEventAdapter）

2. Set up PagerSnapHelper, Achieve the effect of page switching

Specific source code analysis can be viewed ：ViewPager2 Principle analysis - Simple books (jianshu.com)

example 1： Production of simple rotation map

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activity_main.xml

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

    <androidx.viewpager2.widget.ViewPager2 android:layout_width="match_parent" android:layout_height="200dp" android:id="@+id/viewPager" >
    </androidx.viewpager2.widget.ViewPager2>

</LinearLayout>

MainActivity.java

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.RecyclerView;
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);  //  to ViewPager Configure adapter 
    }
}

newly build XML file ： Name it item_pager

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/container">


    <ImageView android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/ivImage" android:layout_centerInParent="true" android:scaleType="centerCrop" />
        <!-- centerCrop  Scale the picture equally ,  Let the short edge of the image match ImageView The length of the side is the same ,  That is, no blank space can be left , After zooming, the middle part is intercepted for display . fitXY  It's the horizontal direction of the original picture （ namely XY Direction ） Drawn after stretching ,  Will change the original proportion  -->


</RelativeLayout>

newly build ViewPagerAdapter.java file

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

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

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


public class ViewPagerAdapter extends RecyclerView.Adapter<ViewPagerAdapter.ViewPagerViewHolder> {
    

    //  Image array 
    private List<Integer> img = new ArrayList<>();

    //  Add an array of pictures to the constructor of the adapter 
    public ViewPagerAdapter(){
    
        img.add(R.drawable.gdufs);
        img.add(R.drawable.gdufs2);
        img.add(R.drawable.world);  //  The pictures here can be added by yourself 
    }


    // onCreatedViewHolder() Method is used to bind item View 
    @NonNull
    @Override
    public ViewPagerViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    
        return new ViewPagerViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_pager,parent,false));
    }


    //  The function of this method is to match the data with the view （ViewHolder） binding 
    @Override
    public void onBindViewHolder(@NonNull ViewPagerViewHolder holder, int position) {
    
        holder.mIv.setImageResource(img.get(position));
    }


    //  return Item The number of , That is to say ViewPager Number of pages you can slide 
    @Override
    public int getItemCount() {
    
        return img.size();
    }


    //  establish ViewHolder Inner class , Used to store and bind instantiated Item object 
    class ViewPagerViewHolder extends RecyclerView.ViewHolder{
    

        ImageView mIv;
        RelativeLayout mContainer;
        public ViewPagerViewHolder(@NonNull View itemView) {
    
            super(itemView);
            mContainer = itemView.findViewById(R.id.container);
            mIv = itemView.findViewById(R.id.ivImage);
        }
    }


}

ViewPager2+Fragment The combination of

example 2： Up and down navigation bar

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level ViewPager

xml file ：

<?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:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.example.ViewPager2.activity.HorizontalScroll">

    <androidx.viewpager2.widget.ViewPager2 android:id="@+id/vp_h" android:layout_width="match_parent" android:layout_height="match_parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

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

import android.os.Bundle;

import com.example.ViewPager2.adapter.HorizontalVpAdapter;
import com.example.viewpagers.R;


public class HorizontalScroll extends AppCompatActivity {
    

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

        ViewPager2 viewPager2 = findViewById(R.id.vp_h);
        HorizontalVpAdapter adapter = new HorizontalVpAdapter(this);
        viewPager2.setAdapter(adapter);

    }
}

Adapter file ：HorizontalVpAdapter.java

package com.example.ViewPager2.adapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;

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

import com.example.viewpagers.R;

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

public class HorizontalVpAdapter extends RecyclerView.Adapter<HorizontalVpAdapter.HorizontalVpViewHolder> {
    

    private List<Integer> backgrounds;
    private Context mContext;

    //  Construction method of adapter , Add different backgrounds to the array 
    public HorizontalVpAdapter(Context context){
    
        mContext = context;
        if(backgrounds == null){
    
            backgrounds = new ArrayList<>();
            backgrounds.add(R.color.blue);
            backgrounds.add(R.color.white);
            backgrounds.add(R.color.black);
            backgrounds.add(R.color.teal_200);
            backgrounds.add(R.color.teal_700);
            backgrounds.add(R.color.purple_200);
        }
    }


    // onCreatedViewHolder() Method is used to bind item View 
    @NonNull
    @Override
    public HorizontalVpViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    
        return new HorizontalVpViewHolder(LayoutInflater.from(mContext)
                .inflate((R.layout.item), parent, false));
    }

    //  The function of this method is to match the data with the view （ViewHolder） binding 
    @Override
    public void onBindViewHolder(@NonNull HorizontalVpViewHolder holder, int position) {
    
        holder.mTextView.setText(" The first  " + (position + 1) + " Interface ");
        holder.mLinearLayout.setBackgroundColor(backgrounds.get(position));
    }


    //  return Item The number of , That is to say ViewPager Number of pages you can slide 
    @Override
    public int getItemCount() {
    
        if(backgrounds == null){
    
            return 0;
        }
        return backgrounds.size();
    }


    //  establish ViewHolder Inner class , Used to store and bind instantiated Item object 
    class HorizontalVpViewHolder extends RecyclerView.ViewHolder {
    
        private LinearLayout mLinearLayout;
        private TextView mTextView;

        HorizontalVpViewHolder(@NonNull View itemView) {
    
            super(itemView);
            mLinearLayout = itemView.findViewById(R.id.item_ll_background);
            mTextView = itemView.findViewById(R.id.item_tv_title);
        }
    }
}

item.xml file ：

<?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="match_parent" android:id="@+id/item_ll_background">


    <TextView android:id="@+id/item_tv_title" android:layout_width="wrap_content" android:layout_height="wrap_content" />

</LinearLayout>

vertical ViewPager

The vertical is the same as the horizontal , Only need android:orientation=“vertical” that will do , Others are the same

<androidx.viewpager2.widget.ViewPager2 android:id="@+id/vp_v" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"/>

Bottom navigation bar ——RadioGroup And ViewPager 2 Continuous use

java file NavigationBottom.java

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

import android.os.Bundle;
import android.widget.RadioButton;
import android.widget.RadioGroup;

import com.example.ViewPager2.adapter.RgAdapter;
import com.example.ViewPager2.fragment.HomeFragment;
import com.example.ViewPager2.fragment.MessageFragment;
import com.example.ViewPager2.fragment.MyFragment;
import com.example.viewpagers.R;


public class NavigationBottom extends AppCompatActivity implements RadioGroup.OnCheckedChangeListener {
    

    private ViewPager2 vpRg;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_navigation_bottom);
        RgAdapter adapter = new RgAdapter(this);

        RadioGroup rg = findViewById(R.id.rg);
        vpRg = findViewById(R.id.vp_rg);
        rg.setOnCheckedChangeListener(this);

        vpRg.setAdapter(adapter);
        adapter.addFragment(new HomeFragment());
        adapter.addFragment(new MessageFragment());
        adapter.addFragment(new MyFragment());
        vpRg.setCurrentItem(0);

        //  This method can monitor  ViewPager 2  The interface changes , Then operate other controls .
        vpRg.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
    
            @Override
            public void onPageSelected(int position) {
    
                super.onPageSelected(position);
                switch (position){
    
                    case 0:
                        ((RadioButton)findViewById(R.id.rb_home)).setChecked(true);
                        break;
                    case 1:
                        ((RadioButton)findViewById(R.id.rb_msg)).setChecked(true);
                        break;
                    case 2:
                        ((RadioButton)findViewById(R.id.rb_my)).setChecked(true);
                        break;
                }
            }
        });


    }

    @Override
    public void onCheckedChanged(RadioGroup group, int checkedId) {
    
        switch (checkedId){
    
            case R.id.rb_home:
                vpRg.setCurrentItem(0);
                break;
            case R.id.rb_msg:
                vpRg.setCurrentItem(1);
                break;
            case R.id.rb_my:
                vpRg.setCurrentItem(2);
                break;
        }
    }


}

Adapter file RgAdapter.java

import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.viewpager2.adapter.FragmentStateAdapter;

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

public class RgAdapter extends FragmentStateAdapter {
    

    private List<Class> fragments;

    public RgAdapter(@NonNull FragmentActivity fragmentActivity){
    
        super(fragmentActivity);
        if(fragments == null){
    
            fragments = new ArrayList<>();
        }
    }

    public void addFragment(Fragment fragment){
    
        if(fragments != null){
    
            fragments.add(fragment.getClass());
        }
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
    
        try {
    
            return (Fragment) fragments.get(position).newInstance();
        } catch (IllegalAccessException e) {
    
            e.printStackTrace();
        } catch (InstantiationException e) {
    
            e.printStackTrace();
        }
        return null;
    }

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

newly build color Folder ：select_rg.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="@color/teal_200" android:state_checked="true"/>
    <item android:color="@color/grey" android:state_checked="false" />
</selector>

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

    <androidx.viewpager2.widget.ViewPager2 android:id="@+id/vp_rg" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_above="@+id/rg"/>

    <View android:layout_width="match_parent" android:layout_height="0.5dp" android:background="#d9d9d9" android:layout_above="@id/rg" />


    <RadioGroup android:id="@+id/rg" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:orientation="horizontal" android:paddingTop="5dp" >

        <RadioButton android:id="@+id/rb_home" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:button="@null" android:checked="true" android:drawableTop="@drawable/selector_home" android:drawablePadding="5dp" android:gravity="center" android:paddingTop="5dp" android:paddingBottom="5dp" android:text="@string/home" android:textColor="@color/select_rg" android:textSize="16sp" />


        <RadioButton android:id="@+id/rb_msg" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:button="@null" android:drawableTop="@drawable/selector_msg" android:drawablePadding="5dp" android:gravity="center" android:paddingTop="5dp" android:paddingBottom="5dp" android:text="@string/msg" android:textColor="@color/select_rg" android:textSize="16sp"/>

        <RadioButton android:id="@+id/rb_my" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="1" android:button="@null" android:drawableTop="@drawable/selector_my" android:drawablePadding="5dp" android:gravity="center" android:paddingTop="5dp" android:paddingBottom="5dp" android:text="@string/my" android:textColor="@color/select_rg" android:textSize="16sp"/>

    </RadioGroup>


</RelativeLayout>

Top navigation bar ——TabLayout And ViewPager 2 Continuous use

NavigationTop.java file

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

import android.graphics.Color;
import android.os.Bundle;

import com.example.ViewPager2.adapter.TabAdapter;
import com.example.viewpagers.R;
import com.google.android.material.tabs.TabLayout;

public class NavigationTop extends AppCompatActivity {
    

    private ViewPager2 vpTab;
    private TabLayout tabVp;

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

        TabAdapter adapter = new TabAdapter(this);
        vpTab = findViewById(R.id.vp_tb);
        tabVp = findViewById(R.id.tb_vp);
        vpTab.setAdapter(adapter);   //  This is very important ！！！
        tabVp.setTabTextColors(Color.parseColor("#111111"),Color.parseColor("#0371DD"));

        adapter.addColor(android.R.color.holo_blue_bright);
        adapter.addColor(android.R.color.holo_red_dark);
        adapter.addColor(android.R.color.holo_green_dark);
        adapter.addColor(android.R.color.holo_blue_dark);
        adapter.addColor(android.R.color.holo_purple);
        adapter.addColor(android.R.color.holo_orange_dark);

        tabVp.addTab(tabVp.newTab().setText(" The first interface "));
        tabVp.addTab(tabVp.newTab().setText(" Second interface "));
        tabVp.addTab(tabVp.newTab().setText(" The third interface "));
        tabVp.addTab(tabVp.newTab().setText(" The fourth interface "));
        tabVp.addTab(tabVp.newTab().setText(" The fifth interface "));
        tabVp.addTab(tabVp.newTab().setText(" Sixth interface "));

        tabVp.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
    
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
    
                vpTab.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {
    

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {
    

            }

        });

        vpTab.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
    
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
    
                super.onPageScrolled(position, positionOffset, positionOffsetPixels);
            }

            @Override
            public void onPageSelected(int position) {
    
                super.onPageSelected(position);
                tabVp.setScrollPosition(position, 0, false);
            }

            @Override
            public void onPageScrollStateChanged(int state) {
    
                super.onPageScrollStateChanged(state);
            }
        });

    }
}

xml file

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" xmlns:app="http://schemas.android.com/apk/res-auto" tools:context="com.example.ViewPager2.activity.NavigationTop" >

    <com.google.android.material.tabs.TabLayout android:id="@+id/tb_vp" android:layout_width="match_parent" android:layout_height="wrap_content" app:tabMode="scrollable" app:tabIndicatorFullWidth="false" app:tabIndicatorColor="#0371DD" app:tabRippleColor="@android:color/transparent" app:tabSelectedTextColor="#0371DD" app:tabTextColor="#111111" app:layout_constraintTop_toTopOf="parent" app:layout_constraintStart_toStartOf="parent" />

    <androidx.viewpager2.widget.ViewPager2 android:layout_below="@id/tb_vp" android:id="@+id/vp_tb" android:layout_width="match_parent" android:layout_height="match_parent" app:layout_constraintTop_toBottomOf="@+id/tb_vp" />


</RelativeLayout>

Add child Fragment——ShowFragment.java

import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

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

import com.example.viewpagers.R;

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

/** * A simple {@link Fragment} subclass. * Use the {@link ShowFragment#newInstance} factory method to * create an instance of this fragment. */
public class ShowFragment extends Fragment {
    

    public ShowFragment() {
    
        // Required empty public constructor
    }

    /** * Use this factory method to create a new instance of * this fragment using the provided parameters. * * @return A new instance of fragment ShowFragment. */
    // TODO: Rename and change types and number of parameters
    public static ShowFragment newInstance(List<Integer> colors, int item) {
    
        ShowFragment fragment = new ShowFragment();
        Bundle args = new Bundle();
        args.putSerializable("color",(ArrayList<Integer>)colors);
        args.putInt("item",item);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
    
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_show, container, false);
    }


    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    
        view.<FrameLayout>findViewById(R.id.fl_show)
                .setBackgroundResource(((ArrayList<Integer>) getArguments()
                        .getSerializable("color")).get(getArguments().getInt("item")));
        view.<TextView>findViewById(R.id.tv_show)
                .setText(" The first  " + (getArguments().getInt("item")+1) + " A page ");
        super.onViewCreated(view, savedInstanceState);
    }
}

fragment_show.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/fl_show" tools:context="com.example.ViewPager2.fragment.ShowFragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView android:id="@+id/tv_show" android:layout_width="match_parent" android:layout_height="match_parent" android:text="@string/hello_blank_fragment" />

</FrameLayout>

Adaptation file ： TabAdapter

import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.viewpager2.adapter.FragmentStateAdapter;

import com.example.ViewPager2.fragment.ShowFragment;

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

public class TabAdapter extends FragmentStateAdapter {
    

    private List<Integer> colors;

    public TabAdapter(@NonNull FragmentActivity fragmentActivity) {
    
        super(fragmentActivity);
        if(colors == null){
    
            colors = new ArrayList<>();
        }
    }

    public void addColor(int color){
    
        if(colors != null){
    
            colors.add(color);
        }
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
    
        return ShowFragment.newInstance(colors,position);
    }

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

expand ：ViewPager2+Fragment+RecyclerView

Reference blog ：https://blog.csdn.net/xiangshiweiyu_hd/article/details/104005810
port androidx.viewpager2.adapter.FragmentStateAdapter;

import com.example.ViewPager2.fragment.ShowFragment;

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

public class TabAdapter extends FragmentStateAdapter {

private List<Integer> colors;

public TabAdapter(@NonNull FragmentActivity fragmentActivity) {
    super(fragmentActivity);
    if(colors == null){
        colors = new ArrayList<>();
    }
}

public void addColor(int color){
    if(colors != null){
        colors.add(color);
    }
}

@NonNull
@Override
public Fragment createFragment(int position) {
    return ShowFragment.newInstance(colors,position);
}

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

}

##  expand ：ViewPager2+Fragment+RecyclerView





 Reference blog ：https://blog.csdn.net/xiangshiweiyu_hd/article/details/104005810