5-2修改数量不知道为什么错了

package com.imooc.goods;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Scanner;

public class ShoppingCart {
	private Map<String, GoodsInCart> shoppingCart;

	Scanner sc = new Scanner(System.in);

	public ShoppingCart() {
		shoppingCart = new HashMap<String,GoodsInCart>();
	}

	public ShoppingCart(Map<String, GoodsInCart> shoppingCart) {
		this.shoppingCart = shoppingCart;
	}

	public Map<String, GoodsInCart> getShoppingCart() {
		return shoppingCart;
	}

	public void setShoppingCart(Map<String, GoodsInCart> shoppingCart) {
		this.shoppingCart = shoppingCart;
	}

	public void addGoodsToCart(GoodsManage gm) { // 添加商品到购物车
		gm.displayAllGoods();
		Iterator<Goods> it = gm.getGoodsSet().iterator();
		boolean flag = true;
		while (flag) {
				System.out.println("请输入要添加的商品编号：");
				String id = sc.next();
				GoodsInCart gic = new GoodsInCart();
				while (it.hasNext()) {
					Goods g = it.next();
					if (id.equals(g.getGoodsId())) {
						gic.setGoods(g);
						break;
					}
				}
				System.out.println("请输入要添加的商品数量：");
				int num = sc.nextInt();
				gic.setNum(num);
				shoppingCart.put(id, gic);
				if(num>0)
					flag = false;
				else
					System.out.println("输入错误，请重新输入！");
					continue;
		}
	}

	public void updateNumInCart() { // 修改购物车中的商品数量
		Iterator<GoodsInCart> it = shoppingCart.values().iterator();
		System.out.println("请输入要修改的商品编号：");
		String id = sc.next();
		GoodsInCart gic = new GoodsInCart();
		while (it.hasNext()) {
			if (id.equals(gic.getGoods().getGoodsId())){
				it.next();
				break;
			}else{
				System.out.println("商品编号不存在");
				continue;
			}
		}
		System.out.println("请输入要修改的商品数量：");
		int num = sc.nextInt();
		gic.setNum(num);
		if(num==0){
			System.out.println("因为商品数量为0，商品被移除");
			shoppingCart.remove(id,gic);
		}else{
			shoppingCart.put(id, gic);
		}
	}

	public void displayAllInCart() { // 显示购物车中的所有商品
		if (shoppingCart.size() != 0) {
			Iterator<GoodsInCart> it = shoppingCart.values().iterator();
			while (it.hasNext()) {
				GoodsInCart gic = it.next();
				Goods g = gic.getGoods();
				System.out.println("商品编号：" + g.getGoodsId() + ",商品名称：" + g.getGoodsName() + ",商品价格：" + g.getPrice()
				+ ",商品描述：" + g.getGoodsDesp() + ",商品数量：" + gic.getNum());
			}
		} else {
			System.out.println("购物车是空的哟，赶紧装满吧~");
		}
	}

	public void settleAccounts() { // 结算
		double sum = 0;
		Iterator<GoodsInCart> it = shoppingCart.values().iterator();
		while (it.hasNext()) {
			GoodsInCart gic = it.next();
			Goods g = gic.getGoods();
			System.out.println("商品编号：" + g.getGoodsId() + ",商品名称：" + g.getGoodsName() + ",商品价格：" + g.getPrice()
					+ ",商品描述：" + g.getGoodsDesp() + ",商品数量：" + gic.getNum());
			double sum1 = g.getPrice() * gic.getNum();
			sum = sum + sum1;
		}
		System.out.println("商品的总价为：" + sum);
		shoppingCart.clear();
	}
}