How do you create an Android View Pager with a dots indicator?

You can check out my library to handle your request : https://github.com/tommybuonomo/dotsindicator

In your XML layout

  <com.tbuonomo.viewpagerdotsindicator.DotsIndicator
      android:id="@+id/dots_indicator"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      app:dotsColor="@color/colorPrimary"
      app:dotsSize="16dp"
      app:dotsWidthFactor="3"
      />

In your Java code

dotsIndicator = (DotsIndicator) findViewById(R.id.dots_indicator);
viewPager = (ViewPager) findViewById(R.id.view_pager);
adapter = new ViewPagerAdapter();
viewPager.setAdapter(adapter);
dotsIndicator.setViewPager(viewPager);

First Create a layout, in that give one LinerLayout for Dots which show over your View Pager

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.v4.view.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>


    <LinearLayout
        android:id="@+id/pager_dots"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="10dp"
        android:background="@android:color/transparent"
        android:gravity="center_horizontal"
        android:orientation="horizontal">
    </LinearLayout>

</RelativeLayout>

After that create 2 drawables

1. Unselected Drawable

<?xml version="1.0" encoding="utf-8"?>
<shape android:shape="oval" xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="@android:color/transparent"/>
    <size android:width="12dp" android:height="12dp"/>

    <stroke android:width="1dp" android:color="#ffffff"/>
</shape>

2. Selected Drawable

<?xml version="1.0" encoding="utf-8"?>
<shape android:shape="oval" xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="@android:color/transparent"/>
    <size android:width="12dp" android:height="12dp"/>

    <stroke android:width="1dp" android:color="#000000"/>
</shape>

After that set adapter

private LinearLayout llPagerDots;
private ViewPager viewPager;
private ArrayList<String> eventImagesUrl;
private HomeViewPagerAdapter homeViewPagerAdapter;
private ImageView[] ivArrayDotsPager;

public void setUpViewPager() {
    viewPager = (ViewPager) findViewById(R.id.view_pager);
    llPagerDots = (LinearLayout) findViewById(R.id.pager_dots);

    homeViewPagerAdapter = new HomeViewPagerAdapter(mContext, eventImagesUrl);

    viewPager.setAdapter(homeViewPagerAdapter);

    setupPagerIndidcatorDots();

    ivArrayDotsPager[0].setImageResource(R.drawable.page_indicator_selected);

    viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
            for (int i = 0; i < ivArrayDotsPager.length; i++) {
                ivArrayDotsPager[i].setImageResource(R.drawable.page_indicator_unselected);
            }
            ivArrayDotsPager[position].setImageResource(R.drawable.page_indicator_selected);
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });
}

Create a method setupPagerIndidcatorDots() :

private void setupPagerIndidcatorDots() {
    ivArrayDotsPager = new ImageView[eventImagesUrl.size()];
    for (int i = 0; i < ivArrayDotsPager.length; i++) {
        ivArrayDotsPager[i] = new ImageView(getActivity());
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        params.setMargins(5, 0, 5, 0);
        ivArrayDotsPager[i].setLayoutParams(params);
        ivArrayDotsPager[i].setImageResource(R.drawable.page_indicator_unselected);
        //ivArrayDotsPager[i].setAlpha(0.4f);
        ivArrayDotsPager[i].setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                view.setAlpha(1);
            }
        });
        llPagerDots.addView(ivArrayDotsPager[i]);
        llPagerDots.bringToFront();
    }

All we need are: ViewPager, TabLayout and 2 drawables for selected and default dots.

Firstly, we have to add TabLayout to our screen layout, and connect it with ViewPager. We can do this in two ways:

---

Nested TabLayout in ViewPager

<androidx.viewpager.widget.ViewPager
    android:id="@+id/photos_viewpager"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.tabs.TabLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
</androidx.viewpager.widget.ViewPager>

In this case TabLayout will be automatically connected with ViewPager, but TabLayout will be next to ViewPager, not over it.

---

Separate TabLayout

<androidx.viewpager.widget.ViewPager
    android:id="@+id/photos_viewpager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

<com.google.android.material.tabs.TabLayout
    android:id="@+id/tab_layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

In this case, we can put TabLayout anywhere, but we have to connect TabLayout with ViewPager programmatically

ViewPager pager = (ViewPager) view.findViewById(R.id.photos_viewpager);
PagerAdapter adapter = new PhotosAdapter(getChildFragmentManager(), photosUrl);
pager.setAdapter(adapter);

TabLayout tabLayout = (TabLayout) view.findViewById(R.id.tab_layout);
tabLayout.setupWithViewPager(pager, true);

Once we created our layout, we have to prepare our dots. So we create three files: selected_dot.xml, default_dot.xml and tab_selector.xml.

---

selected_dot.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape
            android:innerRadius="0dp"
            android:shape="ring"
            android:thickness="8dp"
            android:useLevel="false">
            <solid android:color="@color/colorAccent"/>
        </shape>    
    </item>
</layer-list>

---

default_dot.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape
            android:innerRadius="0dp"
            android:shape="ring"
            android:thickness="8dp"
            android:useLevel="false">
            <solid android:color="@android:color/darker_gray"/>
        </shape>    
    </item>
</layer-list>

---

tab_selector.xml

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

    <item android:drawable="@drawable/selected_dot"
          android:state_selected="true"/>

    <item android:drawable="@drawable/default_dot"/>
</selector>

---

Now we need to add only 3 lines of code to TabLayout in our XML layout.

app:tabBackground="@drawable/tab_selector"
app:tabGravity="center"
app:tabIndicatorHeight="0dp"