/***********************************************************************
  Item01 장점2> 객체를 호출 할 때마다 매번 새로운 객체를 생성할 필요는 없다.
***********************************************************************/
public class Drill {

    private static final Drill GOOD_ID  = new Drill.withId("minikuma");
    private static final Drill GOOD_NUM = new Drill.withNum(100);

    private String id;
    private int num;

    public Drill() { }

    public Drill(String id) {
      this.id = id;
    }
    public Drill(int num) {
      this.num = num;
    }
    public static Drill withId(String id) {
      return new Drill(id);
    }
    public static Drill withNum(int num) {
      return new Drill(num);
    }
    //client 소스에서 사용
    public static void main(String[] args) {
          //미리 생성된 객체를 재 사용
          Drill drill = GOOD_ID;
          Drill numdrill = GOOD_NUM;
    }
  }