Exception in thread

안녕하세요 강사님 제목과 같이 오류 메세지가 나오고 있습니다 ㅜㅜ

문제가 있어 아래 소스 코드 첨부 합니다.

package hello.core.order;

import hello.core.member.*;


public class OderApp {

    public static void main(String[] args) {

        MemberService memberService = new MemberServiceImpl();
        OrderService orderService = new OrderServiceImpl();
        long memberId = 1L;
        Member member = new Member(memberId, "memberA", Grade.VIP);
        memberService.join(member);


        Order order = orderService.createOrder(1L, "itemA", 10000);


    }
}

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "hello.core.member.Member.getGrade()" because "member" is null

at hello.core.discount.FixDiscountPolicy.discount(FixDiscountPolicy.java:14)

at hello.core.order.OrderServiceImpl.createOrder(OrderServiceImpl.java:15)

at hello.core.order.OderApp.main(OderApp.java:17)

이렇게 오류 메세지가 나옵니다

무슨 이유인지는  모르겠지만 Order class안에 값들이 미사용인거 같습니다..

Method 'getMemberId()' is never used

Method 'setMemberId(java.lang.Long)' is never used

Method 'getItemName()' is never used

이렇게 쭉 나옵니다..

package hello.core.order;

public class Order {
    private Long memberId;
    private String itemName;
    private int itemPrice;
    private int discountPrice;

    public Order(Long memberId, String itemName, int itemPrice, int discountPrice) {
        this.memberId = memberId;
        this.itemName = itemName;
        this.itemPrice = itemPrice;
        this.discountPrice = discountPrice;
    }

    public Long getMemberId() {
        return memberId;
    }

    public void setMemberId(Long memberId) {
        this.memberId = memberId;
    }

    public String getItemName() {
        return itemName;
    }

    public void setItemName(String itemName) {
        this.itemName = itemName;
    }

    public int getItemPrice() {
        return itemPrice;
    }

    public void setItemPrice(int itemPrice) {
        this.itemPrice = itemPrice;
    }

    public int getDiscountPrice() {
        return discountPrice;
    }

    public void setDiscountPrice(int discountPrice) {
        this.discountPrice = discountPrice;
    }
}

private static Map<Long, Member> store = new HashMap<>();