Trying to stop a Do-While Loop for an application-CodePudding

I'm creating an application for a homework, the problem is that I am trying to create a do-while loop to exit the application (Using the question "Do you want to exit (Y/N)"). To work with the do-while loop, I created a method to store the app and then called the method in the do-while loop, so that when I try to stop the loop, the method loops once more. I want when I type "Y" to the console the whole program stops and doesn't loop one more time. Thank you for reading.

I created a simple example to explain my problem.

Here's the method:

    public static void App(){
    Scanner sc = new Scanner(System.in);
    
    System.out.print("Write a number: ");
    int num1 = sc.nextInt();
    System.out.print("Write another number: ");
    int num2 = sc.nextInt();
    
    System.out.println("\nResult: " (num1 num2));
}

And here I'm trying to create the loop in the main method:

    public static void main(String[] args) {
    
    Scanner sc2 = new Scanner(System.in);      
    App();
  
    String answer;
    do {
     System.out.println("Do you want to exit (Y/N)?");
     answer = sc2.next();
     App();
    } while (answer.equalsIgnoreCase("N")) ;
}

CodePudding user response：

the problem is that I am trying to create a do-while loop to exit the application

You already have that in your program.

so that when I try to stop the loop, the method loops once more...

That doesn't fit the goal of your program.

I want when I type "Y" to the console the whole program stops and doesn't loop one more time

A lot of context that doesn't fit right in.

But anyway, you just have to reorganize your program.

In other words, just move your App() method.

public static void main(String[] args) {
    
    Scanner sc2 = new Scanner(System.in);      
  
    String answer;
    do {
     App();
     System.out.println("Do you want to exit (Y/N)?");
     answer = sc2.next();
    } while (answer.equalsIgnoreCase("N")) ;
}

Also, I spotted a lot of bad practices, so I kind of fixed them:

public static void main(String[] args) throws Exception {
    try(Scanner sc2 = new Scanner(System.in)){
        String answer;
        do {
            App();
            System.out.print("Do you want to exit (Y/N)?");
            answer = sc2.nextLine();
        } while (answer.equalsIgnoreCase("N")) ;
    }
}

Lastly, maybe (just maybe) try to solve your problem first before seeking help for your homework.

CodePudding user response：

The reason why your program is running again after you type n is because the App() method is ran after the question is asked within the do part of the loop.

This code below is the simplest fix I could think of.

public static void main(String[] args) {
    Scanner sc2 = new Scanner(System.in);
    // I removed the line 'App();' as the App method will always run at least one time. Therefore putting that method within the 'do' part of the loop allows us to ask the user if they wish to exit or not after they have received their answer.
    String answer;
    do {
        App();
        System.out.print("Do you want to exit (Y/N)?"); //I changed the 'println' to 'print' here
        answer = sc2.next();
    } while (answer.equalsIgnoreCase("N")) ;
}

As a side note, methods in java should be lower-case when following typical Java naming conventions. While this will not affect how your code runs, I would suggest renaming the method from App() to app().