如何使用if else和while循环创建计算菜单价格的java代码

Question

我需要使用Java创建一个代码。当任何人进入这家饮料店时，它显示了如何选择和订购菜单项目和数量。选择一个菜单后，代码询问“是否要选择另一个菜单项”。如果不想要其他菜单，请输入（-1）。输入（-1）价格后，通过代码计算，余额超过1000/=商店给10%的折扣。余额中必须加上服务费（20%）和增值税（12%）。

 Scanner scan=new Scanner(System.in);
  int i=0;
  double tot=0,price,vat,service,res=0,result;
 System.out.println("\t\t\t\tWELCOME TO BEVERAGE SHOP");
 System.out.print("User Name:");
 String name=scan.next();
 System.out.println("Hello!!!"+" "+name+" "+"Welcome...");
 System.out.print("\n");
 System.out.println("Please see our menu and select");
 System.out.print("\n");
 System.out.println("|\tPRODUCT ID\t|\t\tPRODUCT NAME\t\t|\tPRICE(LKR)\t|\n|\t1\t\t|\t\tTea\t\t\t|\t80\t\t|\n|\t2\t\t|\t\tCoffee\t\t\t|\t100\t\t|\n|\t3\t\t|\t\tIce Coffee\t\t|\t150\t\t|");
 System.out.print("\n");
 System.out.println("If you have selected the items you want,you can enter the product below");    
 while(i>=0){
     System.out.print("Product Id:");
     int id=scan.nextInt();
     System.out.print("Qyantity:");
     double quan=scan.nextDouble();

     System.out.println(id +":"+quan);

     System.out.print("if you want to stop entering id and buy, please enter \"(-1)\" \nor you want to continue enter anothe number:");
     int no=scan.nextInt();
     if(no==-1){
           vat=(res*12)/100;
           service=(res*20)/100;
           result=vat+service;
      System.out.println("Your Amount is:"+" "+result);
           if(res>1000){
           price=(res*10)/100;
           vat=(res*12)/100;
           service=(res*20)/100;
           result=(vat+service)-price;
           System.out.println("Your Amount is:"+" "+result);
           }
     }
     else{

         switch(id){
              case 1:
                  tot=80*quan;
                  break;
              case 2:
                  tot=100*quan;
                  break;
              case 3:
                  tot=150*quan;
                  break;   
       }
            res+=tot;  
     }  
 }
  i++; 

Answer 1

我将缩短这一点：

int no=scan.nextInt();
while(i>=0){
//your code
    int no=scan.nextInt();
    if(no==-1){
       //your code
       // leave the loop
       break;
    }

 }

需要设置exit/break条件，然后离开while-loop