Datepicker dialog box in android

MAIN ACTIVITY JAVA FILE :

package com.example.viraj.date_picker_type_two;

import android.app.DatePickerDialog;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import java.util.Calendar;

import android.util.Log;
import android.view.View;
import android.widget.DatePicker;
import android.widget.TextView;
import android.app.DatePickerDialog;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";

    private TextView mDisplayDate;
    private DatePickerDialog.OnDateSetListener mDateSetListener;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mDisplayDate = (TextView) findViewById(R.id.tvDate);

        mDisplayDate.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Calendar cal = Calendar.getInstance();
                int year = cal.get(Calendar.YEAR);
                int month = cal.get(Calendar.MONTH);
                int day = cal.get(Calendar.DAY_OF_MONTH);

                DatePickerDialog dialog = new DatePickerDialog(
                        MainActivity.this,
                        android.R.style.Theme_Holo_Light_Dialog_MinWidth,
                        mDateSetListener,
                        year,month,day);
                dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
                dialog.show();
            }
        });

        mDateSetListener = new DatePickerDialog.OnDateSetListener() {
            @Override
            public void onDateSet(DatePicker datePicker, int year, int month, int day) {
                month = month + 1;
                Log.d(TAG, "onDateSet: mm/dd/yyy: " + month + "/" + day + "/" + year);

                String date = month + "/" + day + "/" + year;
                mDisplayDate.setText(date);
            }
        };
    }
}

XML FILE

<?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"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context="com.example.viraj.date_picker_type_two.MainActivity">

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:hint="Select Date"

        android:id="@+id/tvDate"

        android:layout_marginTop="50dp"

        android:layout_centerHorizontal="true"

        android:textSize="30sp"/>

</android.support.constraint.ConstraintLayout>