Sentinel值不会在循环中退出

Question

//在下面的程序中，初始时当用户遇到指令时，他可以简单地输入标记以退出while循环，但是，当您得到您想要的票的结果时买，按999不退出程序

import java.io.*; 

public class ManyTickets 
{ 

    public static void main (String [] args) throws IOException 
    { 
    String userInput; 
    String userInput2; 
    int intInput = 0; 
    int intInput2 = 0; 
    double total = 0.00; 
    BufferedReader ageInput = new BufferedReader (new InputStreamReader (System.in)); 
    try{ 
    System.out.println("Please enter your age, or press '999' to exit."); 
    userInput = ageInput.readLine(); 
    intInput = Integer.parseInt (userInput); 
    while (intInput != 999) 
    { 
     if (intInput < 0 || intInput > 110) 
     System.out.println("Invalid entry, or your age seems a bit too high to enter buy these tickets"); 
     else if (intInput <= 12) 
     { 
     total = total + 6; 
     System.out.println("The ticket cost for 1 ticket is " + total); 
     } 
     else if (intInput <= 64) 
     { 
     total = total + 11; 
     System.out.println("The ticket cost for 1 ticket is " + total); 
     } 
     else 
     { 
     total = total + 8; 
     System.out.println("The ticket cost for 1 ticket is $" + total); 
     } 
     System.out.println("So far, your tickets cost is: $" + total ); 
     System.out.print("Would you like to buy more tickets? You can buy up to 1 more ticket per customer! If no press 999 to exit"); 
     userInput = ageInput.readLine(); 
     intInput2 = Integer.parseInt (userInput); 
     } 
    }catch (NumberFormatException e){ 
     System.out.println("Please restart the program, and enter an integer instead!"); 
    } 
    } 
    { 
    double total = 0.0; 
    System.out.println("Thank you, The total cost for the ticket is: $" + total); 
    System.out.println("Have a nice day!"); 
    } 
} 

Answer 1

用户输入999打破循环后，您没有做任何事情时，其999如下，

intInput2 = Integer.parseInt(userInput); 

if (intInput2 == 999) { 
break; 
} 

Answer 2

您使用两个不同的变量，intInput和intInput2。我不明白你为什么需要第二个（就在catch块之前）。只需重用intInput，这是您在while循环中针对哨兵值进行检查的人。