本质上，我正在用 blueJ 制作一个购物应用程序，但我偶然发现了一个问题。我已经做出了 if 语句，它允许用户 1. 购物 2. 检查购物篮 3. 去结账，当我输入 1 来完成我的购物并将我的东西添加到购物清单时，我似乎无法退出内循环。关于如何解决这个问题的任何想法？import java.util.Scanner;import java.util.ArrayList;public class List{ public String itemsList; ArrayList<String> alist=new ArrayList<String>(); public List() { } /*public String itemList() { System.out.println("1. Veg"); System.out.println("2. sweets"); System.out.println("3. drink"); System.out.println("4. toiletries"); return itemsList; } */ public void Shopping() { Scanner sc = new Scanner(System.in); System.out.println("1. do shopping"); System.out.println("2. check basket"); System.out.println("3. go to checkout"); String choice1 = sc.next(); if(choice1.equals("1")) { boolean stop = false; while(!stop){ Scanner scanner = new Scanner(System.in); System.out.println("1. Veg"); System.out.println("2. sweets"); System.out.println("3. drink"); System.out.println("4. toiletries"); System.out.println("5. alcohol"); System.out.println("6. go back"); String choice = scanner.next(); if(choice.equals("1")) { System.out.println("Veg has been added to your basket"); alist.add("veg"); }else if(choice.equals("2")) { System.out.println("sweets have been added to your basket"); }}
2 回答
万千封印
TA贡献1891条经验 获得超3个赞
1.我可以推荐你对你想做的每一个操作使用不同的方法。通过这种方式，您可以轻松地返回代码的任何部分，因为实际上它会返回一个方法。2.您不必多次启动扫描仪，而在开始时只需一次。3.您可以通过将常见或相似的操作组合成一种方法来优化您的代码。例如，您的代码可以通过以下方式修改：
import java.util.ArrayList;
import java.util.Scanner;
public class List{
static ArrayList<String> alist = new ArrayList<String>();
static Scanner sc = new Scanner(System.in);
static String choice;
public static void main(String args[]){
mainMenue();
}
private static void mainMenue() {
System.out.println("1. do shopping \n2. check basket \n3. go to checkout");
choice = sc.next();
if(choice.equals("1")) shoppingMenue();
else if(choice.equals("2")) checkingMenue();
else if(choice.equals("3")) checkoutMenue();
}
private static void checkoutMenue() {
System.out.println("Are you sure you want to checkout? \n1. No \n2. Yes");
choice = sc.next();
if(choice.equals("1"))return;
else System.out.println("test");
}
private static void checkingMenue() {
System.out.println(alist);
}
private static void shoppingMenue() {
boolean stop = false;
while(!stop){
System.out.println("1. Veg \n2. sweets \n3. drink \n4. toiletries \n5.
alcohol \n6. go back");
choice = sc.next();
if(choice.equals("1")) printAndSave(1);
else if(choice.equals("2")) printAndSave(2);
else if(choice.equals("3")) printAndSave(3);
else if(choice.equals("4")) printAndSave(4);
else if(choice.equals("5")) {
System.out.println("Check ID if age is under 25 \nHow old are you?");
if(sc.nextInt() < 18) System.out.println("You are not old enough to buy
alcohol");
else printAndSave(5);
}
else if(choice.equals("6")) mainMenue();
}
}
private static void printAndSave(int i) {
ArrayList <String> textList = new ArrayList <>(6);
textList.add(0, "");
textList.add(1, "Veg has been added to your basket");
textList.add(2, "Sweets have been added to your basket");
textList.add(3, "Drinks have been added to your basket");
textList.add(4, "Toiletries have been added to your basket");
textList.add(5, "Alcohol has been added to your basket");
System.out.println(textList.get(i));
alist.add("veg");
}
}
MMTTMM
TA贡献1869条经验 获得超4个赞
int num=1;
if(num==1){
while(num<10){
num++;
if(num==5){
break;
}
}
System.out.println(num);
}
输出为 5
这是因为休息；语句跳出它可以找到的最内层循环
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