無限循環或提前終止做while循環

Question

我一直在與這個程序戰鬥一段時間了。它已經開始正確編譯，但是當我按原樣運行它時，它會無限地顯示「您的賬單是__」。當我改變初始響應值時，它拒絕運行。我對如何解決這個問題不知所措。

/* Savannah Moore 
    CSCI 1301 
    2/11/2013 
    Internet Package Code: Code determines customer's final pricing. */ 
import java.util.Scanner; 

public class internet{ 
    public static void main(String[] args){ 
     double hours, price; 
     int internet; 
     String response, check="Yes"; 


     Scanner kb = new Scanner(System.in); /* This sections questions the user as to which package they have bought. */ 
     System.out.println("Our internet packages include:"); 
     System.out.println("Package 1: For $9.95 per month, 10 hours of access are provided. Additional hours are $2.00 per hour."); 
     System.out.println("Package 2: For $13.95 per month, 20 hours of access are provided. Additional hours are $1.00 per hour."); 
     System.out.println("Package 3: For $19.95 per month, unlimited access is provided."); 
     System.out.println("Please enter your package number:"); 
     internet=kb.nextInt(); 
     System.out.println("Please enter your total hours used:"); 
     hours=kb.nextDouble(); 
     response = "Yes"; 

while(check.compareToIgnoreCase(response)== 0) 
    { 
     switch (internet) 
     { 
     case 1: 
       { if (hours > 10) 
         price = (hours-10)*2 + 9.95; /* This adds the additional hours to the user's price at the current overage rate. */ 
        else  
         price = 9.95; 
       } 
       System.out.println("Your bill is $" +price); 
       break; 
     case 2: 
       { if (hours > 20) 
         price = (hours-20) + 13.95; 
        else  
         price = 13.95; 
       } 
       System.out.println("Your bill is $" +price); 
       break;   
    case 3:System.out.println("Your bill is $19.95"); 
       break; 
     default: System.out.println("This package choice is invalid."); 

     System.out.println("Would you like to compare your price with that of another package? Yes or No"); /* This gives the user the ability to stop the loop. */ 
     response=kb.nextLine(); 
     response=kb.nextLine(); 
    } 
    } 

    System.out.println("Thank you for using us as your internet service provider. Have a nice day!"); 
    } 
    } 

Answer 1

循環變得無限，因爲用戶將響應更改爲'否'的機會在case語句中。因此，當你的案件陳述中出現break;時，你立即跳回'while'檢查，並且因爲回覆和檢查都是'是'，它再次執行。

只要在案件陳述中的default:案件後面加上那些陳述，它應該可以工作。

換句話說，變革：

... 
    default: System.out.println("This package choice is invalid."); 

    System.out.println("Would you like to compare your price with that of another package? 
     Yes or No"); /* This gives the user the ability to stop the loop. */ 
    response=kb.nextLine(); 
    response=kb.nextLine(); 
    } 
} 

到：

 ... 
    default: System.out.println("This package choice is invalid."); 
    } 
    System.out.println("Would you like to compare your price with that of another package? 
     Yes or No"); /* This gives the user the ability to stop the loop. */ 
    response=kb.nextLine(); 
    response=kb.nextLine(); 
} 

我不知道你爲什麼這樣做response=kb.nextLine();兩次。

Answer 2

這應該做的伎倆

import java.lang.*; 
import java.util.Scanner; 

public class Program 
{ 
    /** 
    * This is the main entry point for the application 
    */ 
    public static void main(String[] args){ 
     double hours, price; 
     int internet; 
     String response, check="Yes"; 


     response = "Yes"; 

while(check.compareToIgnoreCase(response)== 0) 
    { 

     Scanner kb = new Scanner(System.in); /* This sections questions the user as to which package they have bought. */ 
     System.out.println("Our internet packages include:"); 
     System.out.println("Package 1: For $9.95 per month, 10 hours of access are provided. Additional hours are $2.00 per hour."); 
     System.out.println("Package 2: For $13.95 per month, 20 hours of access are provided. Additional hours are $1.00 per hour."); 
     System.out.println("Package 3: For $19.95 per month, unlimited access is provided."); 
     System.out.println("Please enter your package number:"); 
     internet=kb.nextInt(); 
     System.out.println("Please enter your total hours used:"); 
     hours=kb.nextDouble(); 
     switch (internet) 
     { 
     case 1: 
       { if (hours > 10) 
         price = (hours-10)*2 + 9.95; /* This adds the additional hours to the user's price at the current overage rate. */ 
        else  
         price = 9.95; 
       } 
       System.out.println("Your bill is $" +price); 
       break; 
     case 2: 
       { if (hours > 20) 
         price = (hours-20) + 13.95; 
        else  
         price = 13.95; 
       } 
       System.out.println("Your bill is $" +price); 
       break;   
    case 3:System.out.println("Your bill is $19.95"); 
       break; 
     default: System.out.println("This package choice is invalid."); 
     } 
     System.out.println("Would you like to compare your price with that of another package? Yes or No"); /* This gives the user the ability to stop the loop. */ 
     response=kb.nextLine(); 
     response=kb.nextLine(); 

    } 

    System.out.println("Thank you for using us as your internet service provider. Have a nice day!"); 
    } 
}