Viewpager 2 in Android

 

useful blogs & videos : 

https://youtu.be/-wB_JE_PRTo

https://medium.com/google-developer-experts/exploring-the-view-pager-2-86dbce06ff71

https://blog.usejournal.com/early-introduction-of-viewpager2-ff38c60d2169

UnLike RecyclerView , the Single Row Design must have a height of "Match Parent" , else viewpager2 wont work.

ViewPager2 needs an adapter. For this, we can either use RecyclerView.Adapter or FragmentStateAdapter which supports fragment out of the box. We will use FragmentStateAdapter for now.

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Viewpager 2 implements a RecyclerView behind the scenes.

To Attach ViewPager2 & TabLayout , you can use the below code of line to attach them inside the OnCreate( ) 

 viewpager2.setAdapter(new ViewPagerAdapter(Arrays.asList(images)));

TabLayoutMediator tabLayoutMediator = new TabLayoutMediator(
        tabLayout,viewpager2,
        (tab, position) -> tab.setText("OBJECT " + (position + 1)) );
tabLayoutMediator.attach();

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SIMPLE VIEWPAGER IN JAVA :

(swipe single images)

activity_main.xml

<?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=".MainActivity">


    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewpager2"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

package com.deepesh.viewpager2app;

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

import android.os.Bundle;

import java.util.Arrays;

public class MainActivity extends AppCompatActivity {


    ViewPager2 viewpager2;

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

        viewpager2 = findViewById(R.id.viewpager2);

        Integer[] images = {
                R.drawable.img1,
                R.drawable.img2,
                R.drawable.img3,
                R.drawable.img5
        };

        viewpager2.setAdapter(new ViewPagerAdapter(Arrays.asList(images)));

        viewpager2.setOrientation(ViewPager2.ORIENTATION_VERTICAL);

    }
}

ViewPagerAdapter.java

package com.deepesh.viewpager2app;

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

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

import java.util.List;

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

    List<Integer> images;

    ViewPagerAdapter(List<Integer> images) {
        this.images = images;
    }


    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        View view1 = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_page, parent, false);

        return new MyViewHolder(view1);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        Integer currentImageId = images.get(position);
        holder.imageView.setImageResource(currentImageId);
    }

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


    //VIEWHOLDER CLASS

    static class MyViewHolder extends RecyclerView.ViewHolder {

        ImageView imageView;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);

            imageView = itemView.findViewById(R.id.single_page_image);
        }
    }

}

single_page.xml

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    // In Case of ViewPager , the Layout_Height cannot be "Wrap Content".

    <ImageView
        android:id="@+id/single_page_image"
        android:layout_width="0dp"
        android:layout_height="300dp"
        android:layout_marginStart="55dp"
        android:layout_marginTop="42dp"
        android:src="@drawable/ic_launcher_background"
        android:layout_marginEnd="55dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

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