Tiny app to demonstrate PagerAdapter

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#eee"/>

card.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
    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">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="8dp"
        android:gravity="center"
        tools:text="hello world"/>

</android.support.v7.widget.CardView>

MainActivity.java

package com.example.stackoverflow;

import android.os.Bundle;
import android.support.constraint.ConstraintLayout;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.Arrays;
import java.util.List;

public class MainActivity extends AppCompatActivity {

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

        List<String> items = Arrays.asList("one", "two", "three", "four", "five", "six", "seven", "eight", "nine");
        ViewPager pager = findViewById(R.id.pager);
        pager.setAdapter(new MyAdapter(items));
    }

    private static class MyAdapter extends PagerAdapter {

        private final List<String> items;

        private MyAdapter(List<String> items) {
            this.items = items;
        }

        @Override
        public int getCount() {
            return (items != null)
                   ? ((items.size() - 1) / 6) + 1
                   : 0;
        }

        @Override
        public Object instantiateItem(ViewGroup container, int pageNumber) {
            LayoutInflater inflater = LayoutInflater.from(container.getContext());
            ConstraintLayout page = (ConstraintLayout) inflater.inflate(R.layout.page, container, false);

            for (int i = 0; i < 6; ++i) {
                View child = page.getChildAt(i);
                int position = (pageNumber * 6) + i;

                if (position < items.size()) {
                    TextView text = (TextView) ((ViewGroup) child).getChildAt(0);
                    text.setText(items.get(position));
                }
                else {
                    child.setVisibility(View.GONE);
                }
            }

            container.addView(page);
            return page;
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object key) {
            container.removeView((View) key);
        }

        @Override
        public boolean isViewFromObject(View view, Object key) {
            return view == key;
        }
    }
}

page.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
    android:padding="6dp">

    <include
        layout="@layout/card"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="6dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="@+id/verticalGuideline"
        app:layout_constraintBottom_toBottomOf="@+id/horizontalGuidelineTop"/>

    <include
        layout="@layout/card"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="6dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="@+id/verticalGuideline"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="@+id/horizontalGuidelineTop"/>

    <include
        layout="@layout/card"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="6dp"
        app:layout_constraintTop_toTopOf="@+id/horizontalGuidelineTop"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="@+id/verticalGuideline"
        app:layout_constraintBottom_toBottomOf="@+id/horizontalGuidelineBottom"/>

    <include
        layout="@layout/card"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="6dp"
        app:layout_constraintTop_toTopOf="@+id/horizontalGuidelineTop"
        app:layout_constraintLeft_toLeftOf="@+id/verticalGuideline"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="@+id/horizontalGuidelineBottom"/>

    <include
        layout="@layout/card"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="6dp"
        app:layout_constraintTop_toTopOf="@+id/horizontalGuidelineBottom"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="@+id/verticalGuideline"
        app:layout_constraintBottom_toBottomOf="parent"/>

    <include
        layout="@layout/card"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="6dp"
        app:layout_constraintTop_toTopOf="@+id/horizontalGuidelineBottom"
        app:layout_constraintLeft_toLeftOf="@+id/verticalGuideline"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"/>

    <android.support.constraint.Guideline
        android:id="@+id/verticalGuideline"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.5"/>

    <android.support.constraint.Guideline
        android:id="@+id/horizontalGuidelineTop"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.33"/>

    <android.support.constraint.Guideline
        android:id="@+id/horizontalGuidelineBottom"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.67"/>

</android.support.constraint.ConstraintLayout>