<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    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">

    <!--on below line we are creating our calendar view
        selector color is use as a indicator for selected date
        text color normal is use to give text color to unselected date
        text color selected is use to give text color to selected date-->
    <devs.mulham.horizontalcalendar.HorizontalCalendarView
        android:id="@+id/calendarView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:selectorColor="@android:color/holo_red_dark"
        app:textColorNormal="@color/purple_200"
        app:textColorSelected="@color/purple_200" />

</RelativeLayout>

import android.os.Bundle;
import android.util.Log;

import androidx.appcompat.app.AppCompatActivity;

import java.util.Calendar;

import devs.mulham.horizontalcalendar.HorizontalCalendar;
import devs.mulham.horizontalcalendar.utils.HorizontalCalendarListener;

public class MainActivity extends AppCompatActivity {

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

        /* starts before 1 month from now */
        Calendar startDate = Calendar.getInstance();
        startDate.add(Calendar.MONTH, -1);

        /* ends after 1 month from now */
        Calendar endDate = Calendar.getInstance();
        endDate.add(Calendar.MONTH, 1);

        // on below line we are setting up our horizontal calendar view and passing id our calendar view to it.
        HorizontalCalendar horizontalCalendar = new HorizontalCalendar.Builder(this, R.id.calendarView)
                // on below line we are adding a range 
                // as start date and end date to our calendar.
                .range(startDate, endDate)
                // on below line we are providing a number of dates
                // which will be visible on the screen at a time.
                .datesNumberOnScreen(5)
                // at last we are calling a build method 
                // to build our horizontal recycler view.
                .build();
        // on below line we are setting calendar listener to our calendar view.
        horizontalCalendar.setCalendarListener(new HorizontalCalendarListener() {
            @Override
            public void onDateSelected(Calendar date, int position) {
                // on below line we are printing date 
                // in the logcat which is selected.
                Log.e("TAG", "CURRENT DATE IS " + date);
            }
        });
    }
}