如果用戶輸入'N'，我該如何讓程序退出？

Question

如果用戶輸入'N'，我該如何讓程序退出？

Scanner scan = new Scanner(System.in); 
System.out.println("Would you like to buy and dairy products? Y/N "); 
String answer = scan.nextLine(); 

switch (answer) 
{ 
case "Y": 
case "y": 
    System.out.println("\nHere are our list of dairy products:-"); 
    break; 
case "N": 
case "n"://exit from program; 
    System.out.println("You don't want any dairy items"); 
    break; 
default : 
    System.out.println("Invalid choice, please select Yes/No bu entering the characters 'Y'/'N'"); 
    break; 
} 

Answer 1

假設這是主要的方法中，你可以只使用一個return;聲明，從而結束該方法，因此該程序。

否則System.exit()將工作。

Answer 2

做的稍微好一點的辦法......你做什麼：

Scanner scan = new Scanner(System.in); 

System.out.println("Would you like to buy any dairy products? Y/N "); 
String answer = ""; 

while (!answer.equals("y") && !answer.equals("n")) { 
    answer = scan.nextLine().toLowerCase(); 

    switch (answer) { 
     case "y": 
      System.out.println("\nHere are our list of dairy products:-"); 
      break; 
     case "n"://exit from program; 
      System.out.println("You don't want any dairy items"); 
      System.exit(0); // program terminates if N or n was supplied. 
      break; 
     default : 
      System.out.println("Invalid choice, please select Yes/No by entering the characters Y or N"); 
      break; 
    } 
} 
// Code continues here if Y or y was supplied.