How do I translate data from Calendar to Date?

For the test, I call the calendar to select the date

Layout

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:orientation="vertical">

<TextView android:id="@+id/currentDateTime"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:textSize="18sp" />

<Button android:id="@+id/dateButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Изменить дату"
        android:onClick="setDate"  />

public class MainActivity extends AppCompatActivity {

TextView currentDateTime;
Calendar dateAndTime=Calendar.getInstance();
@Override
public void onCreate(Bundle savedInstance) {
    super.onCreate(savedInstance);
    setContentView(R.layout.activity_main);
    currentDateTime=(TextView)findViewById(R.id.currentDateTime);
    setInitialDateTime();
}

// окно для выбора даты
public void setDate(View v) {
    new DatePickerDialog(MainActivity.this, d,
            dateAndTime.get(Calendar.YEAR),
            dateAndTime.get(Calendar.MONTH),
            dateAndTime.get(Calendar.DAY_OF_MONTH))
            .show();
}

// установка текущей даты для textview
private void setInitialDateTime()
{
    SimpleDateFormat sdf = new SimpleDateFormat("dd - MM - yyyy");
    String date = sdf.format(new Date().getTime());
    currentDateTime.setText(date);
}

//обработчик выбора даты
DatePickerDialog.OnDateSetListener d = new DatePickerDialog.OnDateSetListener() {
    public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
        dateAndTime.set(Calendar.YEAR, year);
        dateAndTime.set(Calendar.MONTH, monthOfYear);
        dateAndTime.set(Calendar.DAY_OF_MONTH, dayOfMonth);
        setInitialDateTime();
    }
};
}

How do I convert this calendar data to Date format ? so that you can save the selected date in the SQL database Roughly speaking, I want to fill the textview with a date from the database, but to write the date to the database, it needs to be somehow converted from the calendar format

As a result of the responses received, part of the code turned into

    private void setInitialDateTime()
{
    SimpleDateFormat sdf = new SimpleDateFormat("dd - MM - yyyy");
    String date = sdf.format(dateAndTime.getTime());
    currentDateTime.setText(date);
}