Java菜單使用Do while循環不斷重複

Question

此代碼應該顯示一個菜單，之後它應該給用戶從菜單中選擇的可能性。用戶可以隨着數量選擇3個項目，之後顯示總價格並停止程序。 這是程序應該是什麼在運行時，如：

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: 

用戶後輸入比薩餅的數量要求，並且工作正常。 用戶必須被要求3次才能進入披薩和數量，但是循環不會停下來並不停地詢問和詢問，這是我的問題！ 以下是代碼：

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，或幫助高度讚賞:)。

Answer 1

您的陳述count = count++看起來不對。僅使用count++或count = count + 1。

使用count = count++創建字節碼有點像這樣：

​​

所以實際上計數沒有得到增加。

使用count = ++count應該工作，但在邏輯上看起來錯誤：

count = count + 1 
count = count 

最好不要嘗試編譯器的有趣的特性。

Answer 2

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

您只需編寫「i ++;」然後你很好。

而順便說一句。從來沒有存錢的浮動或雙）

編輯：

int i = 1; 
i = ++i; 

，因爲你是我增加分配新值之前這將是可能的。

Answer 3

你有幾件事情可以在你的程序中改進。首先，讓我們來看看這個bug，你說的是count = count ++，但是通過這樣做，編譯器將開始遞增計數值，然後將計數恢復到它的舊值，因爲count++將返回不是遞增值。爲了簡化，這個聲明什麼也不做，也不增加count的值。

當你想增加，使用後綴操作符： count++;

通過分析你的程序，你可以注意到很多重複的代碼可以減少！

例如，比較輸入時，您可以使用.equals()，這樣你就不必爲大寫和小寫分裂的情況：

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

相當於

cas.equals('f') 

您可以重複其他情況。

在每個if語句中，您正在執行相同的system.out.println。爲了簡單起見，你可以聲明打印一個變量，像

String typeofPizza; 

，然後將每個if

typeofPizza = "Margherita"; 

這樣裏面，可以取出打印到if條款的結束：

System.out.println("Total for " + quant + typeofPizza + "is :" + total); 

Answer 4

感謝您的早期迴應:)。程序運行良好。我無法相信一個犯這種低級錯誤count ++而不是++ count。我也發生了變化詮釋計數到而不是。