Set year, month and day to a date

import java.util.Calendar;
import java.util.Date;

public class Main {
  public static void setDay(Date date, int day) {
    if (date == null)
      return;
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    cal.set(Calendar.DAY_OF_MONTH, day);
  }

  public static void setMonth(Date date, int month) {
    if (date == null)
      return;
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    cal.set(Calendar.MONTH, month - 1);
  }

  public static void setYear(Date date, int year) {
    if (date == null)
      return;
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    cal.set(Calendar.YEAR, year);
  }
}