Android Creating a DatePickerDialog

MainActivity.java

public class MainActivity extends AppCompatActivity {

    Button buttonShow;

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

        buttonShow= (Button) findViewById(R.id.buttonShow);
        buttonShow.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                CustomDatePicker customDatePicker=new CustomDatePicker();
                customDatePicker.show(getSupportFragmentManager(),"customDatePicker1");
            }
        });
    }
}

CustomDatePicker.java

public class CustomDatePicker extends DialogFragment {
    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {

        Calendar calendar=Calendar.getInstance();

        int year=calendar.get(Calendar.YEAR);
        int month=calendar.get(Calendar.MONTH);
        int day=calendar.get(Calendar.DAY_OF_MONTH);

        final DatePickerDialog datePickerDialog=new DatePickerDialog(getContext(), new DatePickerDialog.OnDateSetListener() {
            @Override
            public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
                String output=String.format("%s:%s:%s",year,month,dayOfMonth);
                Toast.makeText(getContext(),output,Toast.LENGTH_LONG).show();
            }
        },year,month,day);



        return datePickerDialog;
    }
}

References
https://github.com/mhdr/AndroidSamples/tree/master/019