Question

此代码应显示一个菜单，然后它应该让用户可以从菜单中进行选择。用户可以选择3个项目以及数量，然后显示总价格并停止程序。这是程序在运行时的样子：

This is the menu for Tal'Qroq Restourant:


This is the menu of pizzas

A.Margherita ..... $5.50
B.Capricosa ..... $6.50
C.Funghi ..... $7.00
D.Vegeterian..... $7.00
E.Tropical..... $8.00
F.Meat ..... $8.00
G.Salami..... $8.00
H.Maltija..... $8.00
I.Calzona..... $8.50
J.Tal'Qroq special..... $8.00 

Enter your pizza order according to the menu letters:

用户输入比萨饼后，会询问数量并且工作正常。用户必须被要求3次输入披萨和数量，但循环不会停止并继续询问和无限询问这是我的问题！以下是代码：

public class Menu{
    public static void main (String[]args){

    float total = 0;
    char cas = 0;
    int quant = 0;
    int count = 0;

    System.out.println("This is the menu for Tal'Qroq Restourant:");
    System.out.println("\n");
    System.out.println("This is the menu of pizzas");
    System.out.println("\n");
    System.out.println("A.Margherita ..... $5.50");
    System.out.println("\n");
    System.out.println("B.Capricosa ..... $6.50");
    System.out.println("\n");
    System.out.println("C.Funghi ..... $7.00");
    System.out.println("\n");
    System.out.println("D.Vegeterian..... $7.00");
    System.out.println("\n");
    System.out.println("E.Tropical..... $8.00");
    System.out.println("\n");
    System.out.println("F.Meat ..... $8.00");
    System.out.println("\n");
    System.out.println("G.Salami..... $8.00");
    System.out.println("\n");
    System.out.println("H.Maltija..... $8.00");
    System.out.println("\n");
    System.out.println("I.Calzona..... $8.50");
    System.out.println("\n");
    System.out.println("J.Tal'Qroq special..... $8.00");
    System.out.println("\n");

    float a = 5.50f;
    float b = 6.50f;
    float c = 7.00f;
    float d = 7.00f;
    float e = 8.00f;
    float f = 8.00f;
    float g = 8.00f;
    float h = 8.00f;
    float i = 8.00f;
    float j = 8.00f;


    do{
        System.out.print("Enter your pizza order according to the menu letters: ");
        cas = Keyboard.readChar(); 

        System.out.print("Enter the ammount of pizza you want: ");
        quant = Keyboard.readInt();

         if(cas == 'a' || cas == 'A'){
        System.out.println("Total for " + quant + " Margherita is :" + (a*quant));
        System.out.println("\n");
        total = total + (a*quant);
        count = count++;

        }else if(cas == 'b' || cas == 'B'){
            System.out.println("Total for " + quant + " Capricosa is :" + (b*quant));
            System.out.println("\n");
            total = total + (b*quant);
            count = count++;

        }else if(cas == 'c' || cas == 'C'){
            System.out.println("Total for " + quant + " Funghi is :" + (c*quant));
            System.out.println("\n");
            total = total + (c*quant);  
            count = count++;

        }else if(cas == 'd' || cas == 'D'){
            System.out.println("Total for " + quant + " Vegeterian is :" + (d*quant));
            System.out.println("\n");
            total = total + (d*quant);
            count = count++;

        }else if(cas == 'e' || cas == 'E'){
            System.out.println("Total for " + quant +  " Tropical is :" + (e*quant));
            System.out.println("\n");
            total = total + (e*quant);
            count = count++;

        }else if(cas == 'f' || cas == 'F'){
            System.out.println("Total for " + quant + " Meat is :" + (f*quant));
            System.out.println("\n");
            total = total + (f*quant);
            count = count++;

        }else if(cas == 'g' || cas == 'G'){
            System.out.println("Total for " + quant + " Salami is :" + (g*quant));
            System.out.println("\n");
            total = total + (g*quant);
            count = count++;

        }else if(cas == 'h' || cas == 'H'){
            System.out.println("Total for " + quant + " Calzona is :" + (h*quant));
            System.out.println("\n");
            total = total + (h*quant);
            count = count++;

        }else if(cas == 'i' || cas == 'I'){
           System.out.println("Total for " + quant + " Maltija is :" + (i*quant));
           System.out.println("\n");
           total = total + (i*quant);
           count = count++;

        }else if(cas == 'j' || cas == 'J'){
           System.out.println("Total for " + quant + " Tal'Qroq special is :" + (j*quant));
           System.out.println("\n");
           total = total + (j*quant);
           count = count++;
        }else{
        System.out.println("Your selection isn't avaliable in our Menu!");
        System.out.println("\n");
    }    
    } while (count <= 3);
    System.out.println("Your total is €" + total);
}

}

任何答案或帮助都非常感谢：）。

Answer 1

您的陈述ReflectionException in Container.php line 736: Class swaggable\Http\Controllers\back\controllers\BackToolsController does not exist看起来不对。仅使用count = count++或count++。

使用count = count + 1创建字节代码有点像这样：

count = count++

因此实际上计数不会增加。

使用temp = count count = count + 1 count = temp应该有效，但逻辑上看错了：

count = ++count

最好不要尝试编译器的有趣的特性。

Answer 2

int i = 1;
i = i++;
System.out.prinln(i); //-> 1

你必须写＆＃34; i ++;＆＃34;然后你很好。

顺便说一下。永远不会在浮动或双重中存钱;）

编辑：

int i = 1;
i = ++i;

这是可能的，因为你在分配新值之前增加了我。

Answer 3

您可以在程序中改进几件事。首先，让我们来看看这个bug，你说的是count = count ++但是通过这样做，编译器将首先递增count的值，然后将count恢复为旧的值，因为{{1}将返回不是递增的值。为简化起见，此语句不执行任何操作，也不增加count++的值。

如果要增加，请使用后缀运算符： count;

通过分析您的程序，您可以注意到许多可以减少的重复代码！

例如，在比较输入时，您可以使用count++，这样您就不必将大小写分割为大写和小写：

.equals()

相当于

(cas == 'f' || cas == 'F')

您可以重复其余的案例。

在每个if语句中，您正在执行相同的cas.equals('f')。为简单起见，您可以声明一个用于打印的变量，例如

system.out.println

然后在每个String typeofPizza;

内

if

这样，您可以将打印件移除到typeofPizza = "Margherita";子句的末尾：

if

Answer 4

感谢您的早期回复:)。该程序运行良好。我无法相信犯了这样一个愚蠢的错误count ++而不是++ count。我还将int count改为 1 而不是<强> 0

Java菜单使用Do while循环不断重复

4 个答案: