如何在 java 中存储整数的更新值？

Question

这是我的自动售货机代码-

import java.util.Scanner;

public class VendingMachine
{
    public static final Scanner sc = new Scanner(System.in);
    public static double totalAmt;
    public static double change;
    public static String food = null;
    public static int stockPC = 2;
    public static int stockCo = 2;
    public static int stockCa = 2;
    
    public static void MainMenu(){
        
         System.out.println("Main menu - "); 
         System.out.println("a - Potato Chips -.25");
         System.out.println("b - Cookies - [=11=].85 ");
         System.out.println("c - Candies - [=11=].95");
         
         
         
         String input = sc.next().toLowerCase(); 
         change = 0;
         if(input.equals("a")){
            stockPC = stockPC -1;
            change = totalAmt - 1.25;
            food ="Potato chips";
                if(stockPC == 0){
                 System.out.println("Sorry we're out of Potato Chips:(");
                }else{
                    System.out.println("Please take your "+ food + "\n");       
                     System.out.println("Here is your change $" + change);
                }

         }else if ( input.equals("b")){
            stockCo = stockCo -1;
            change = totalAmt - 0.85;
            food ="Cookies";
                 if(stockCo == 0){
                 System.out.println("Sorry we're out of Cookies:(");
                }else{
                    System.out.println("Please take your "+ food + "\n");       
                     System.out.println("Here is your change $" + change);
                }
         }else if ( input.equals("c")){
            stockCa = stockCa -1;
            change = totalAmt - 0.95;
            food ="Candies";
                 if(stockCa == 0){
                 System.out.println("Sorry we're out of Candies:(");
                }else{
                    System.out.println("Please take your "+ food + "\n");       
                     System.out.println("Here is your change $" + change);
                }
         }else{
               System.out.println("Our system only accepts a,b or c");
         }
         
        }
    
    
    public static void main(String[] args){
         System.out.println("Hi! Welcome to Vending Machine!");
         
        
         System.out.println("How many quarters do you have?");
         double noOfQt = sc.nextDouble();
         totalAmt = noOfQt * 0.25;
         
         System.out.println("How many dimes do you have?");
         double noOfDm = sc.nextDouble();
         totalAmt = totalAmt + (noOfDm * 0.1);
         
         System.out.println("How many nickels do you have?");
         double noOfNk = sc.nextDouble();
         totalAmt = totalAmt + (noOfNk * 0.05);
         
         System.out.println("You have = $" + totalAmt);
         
         MainMenu();
            
         }
    }

我的 MainMenu 方法有问题。在我的 MainMenu 方法中选择一个输入后，我想在方法结束时更新 'integers' 的值，如 change、stockPC、stockCo 和 stockCo。我不想打印这些值。我只想在我的主要方法中使用这些更新后的值。

我该怎么做？

Answer 1

你在哪里实例化你的扫描仪？它需要成为 main 方法的一部分，然后将来自用户的值传递给 MainMenu(-put value here-) 方法。这样 -> 扫描仪就可以工作了。

MainMenu(double amount);

在接收方法中进行计算，只传递来自用户的“通用”双重输入

此外，在您的情况下，将库存中的商品声明为 public 静态并不是一个好的做法。请记住，将变量声明为私有变量并使用 setters/getters 始终是一个好习惯。

不应像您那样初始化数据成员，而是：

private int stockPC;
private int stockCo;
private int stockCa;

使用构造函数定义初始化时的值：

 public VendingMachine(int stockPC, int stockCo, int stock){
 this.stockPC = stockPC;
 this.stockCo = stockCo;
 this.stockCa = stockCa;
}

最后 getters/setters:

public int getStockPC(){
return stockPC;}

public int getstockCo(){
return stockCo;}

public int stockCa(){
return stockCa;}

public void setstockPC(int stockPC){
this.stockPC = stockPC;}

public void stockCo(int stockCo){
this.stockCo = stockCo;}

public void stockCa(int stockCa){
this.stockCa = stockCa;}

希望对您有所帮助

Answer 2

我做了一台永不停止服务的自动售货机。 :D 如果您的金额少于 select 选项的价格，我也添加了金额条件，它将显示消息。

您的代码是正确的，因为您需要的只是缺少一些条件并且不正确。你想要的是 while 循环。但我已根据我的理解更正了您的条件并添加了所需的条件。如果你愿意，你可以删除这些条件。

import java.util.Scanner;

public class Main
{
public static final Scanner sc = new Scanner(System.in);
public static double totalAmt;
public static double change;
public static String food = null;
public static int stockPC = 2;
public static int stockCo = 2;
public static int stockCa = 2;

public static void MainMenu(){
    
     System.out.println("Main menu - "); 
     System.out.println("a - Potato Chips -.25");
     System.out.println("b - Cookies - [=10=].85 ");
     System.out.println("c - Candies - [=10=].95");
     
     String input = sc.next().toLowerCase(); 
     change = 0;
     if(input.equals("a")){
        stockPC = stockPC -1;
        //when stockPC is -1 means stock was zero and you want 1 more
        if(stockPC == -1){
            System.out.println("Sorry we're out of Potato Chips:(");
        }else{
            change = totalAmt - 1.25;
            if(change<0){
                System.out.println("You don't have enough amount to buy");
            }else{
                food ="Potato chips";
                System.out.println("Please take your "+ food + "\n");       
                System.out.println("Here is your change $" + change);
            }
        }
     }else if ( input.equals("b")){
        stockCo = stockCo -1;
        //when stockCo is -1 means stock was zero and you want 1 more
        if(stockCo == -1){
            System.out.println("Sorry we're out of Cookies:(");
        }else{
            change = totalAmt - 0.85;
            if(change<0){
                System.out.println("You don't have enough amount to buy");
            }else{
                food ="Cookies";
                System.out.println("Please take your "+ food + "\n");       
                System.out.println("Here is your change $" + change);
            }
        }
     }else if ( input.equals("c")){
        stockCa = stockCa -1;
        //when stockCa is -1 means stock was zero and you want 1 more
        if(stockCa == 0){
            System.out.println("Sorry we're out of Candies:(");
        }else{
            change = totalAmt - 0.95;
            if(change<0){
                System.out.println("You don't have enough amount to buy");
            }else{
                food ="Candies";
                System.out.println("Please take your "+ food + "\n");       
                System.out.println("Here is your change $" + change);
            }
        }
     }else{
           System.out.println("Our system only accepts a,b or c");
     }
    }

public static void main(String[] args){
     System.out.println("Hi! Welcome to Vending Machine!");
     
    
     System.out.println("How many quarters do you have?");
     double noOfQt = sc.nextDouble();
     totalAmt = noOfQt * 0.25;
     
     System.out.println("How many dimes do you have?");
     double noOfDm = sc.nextDouble();
     totalAmt = totalAmt + (noOfDm * 0.1);
     
     System.out.println("How many nickels do you have?");
     double noOfNk = sc.nextDouble();
     totalAmt = totalAmt + (noOfNk * 0.05);
     
     System.out.println("You have = $" + totalAmt);
     
     while(true){
        MainMenu();
     }
        
     }
}

如何在 java 中存储整数的更新值？

How to store updated value of an integer in java?

java

store