CODEWITHSUNDEEP
javaeclipsemenu
PrgmRNoob
PrgmRNoob

Reputation: 151

Creating a console menu for user to make a selection

Doing a program in Eclipse with Java. What I want to do is when I execute the program I want present the user with a choice. I have all the calculations etc. done, I'm just unsure as to how to make this menu to offer the user choices. Example of what I'm looking for:

To enter an original number: Press 1
To encrypt a number: Press 2
To decrypt a number: Press 3
To quit: Press 4
Enter choice:



public static void main(String[] args) {
    Data data = new Data(); 
    data.menu(); }
}

Upvotes: 4

Views: 97037

Answers (2)

Sh0cK v
Sh0cK v

Reputation: 101

For simplicity's sake I would recommend using a static method that returns an integer value of the option.

    public static int menu() {

        int selection;
        Scanner input = new Scanner(System.in);

        /***************************************************/

        System.out.println("Choose from these choices");
        System.out.println("-------------------------\n");
        System.out.println("1 - Enter an original number");
        System.out.println("2 - Encrypt a number");
        System.out.println("3 - Decrypt a number");
        System.out.println("4 - Quit");

        selection = input.nextInt();
        return selection;    
    }

Once you have the method complete you would display it accordingly in your main method as follows:

    public static void main(String[] args) {

        int userChoice;

        /*********************************************************/

        userChoice = menu();

        //from here you can either use a switch statement on the userchoice 
        //or you use a while loop (while userChoice != the fourth selection)
        //using if/else statements to do your actually functions for your choices.
    }

hope this helps.

Upvotes: 10

Jon Newmuis
Jon Newmuis

Reputation: 26530

You can use a scanner to read input from System.in, as follows:

public static void main(String[] args) {
    Data data = new Data();
    data.menu();

    Scanner scanner = new Scanner(System.in);
    int choice = scanner.nextInt();

    switch (choice) {
        case 1:
            // Perform "original number" case.
            break;
        case 2:
            // Perform "encrypt number" case.
            break;
        case 3:
            // Perform "decrypt number" case.
            break;
        case 4:
            // Perform "quit" case.
            break;
        default:
            // The user input an unexpected choice.
    }
}

Note that this will require the user to input a number and press enter, before continuing execution. If they enter invalid input, this will halt; if you want it to prompt them again, you will need to wrap this in a loop of some sort, depending on how you want the system to behave.

Scanner#nextInt may very well throw an exception, should the user input something that cannot be parsed to an integer. You can catch this exception and handle it appropriately. If the user enters an integer that is out of the range of valid options (i.e. it is not in the range of 1-4), it will fall to the default branch of the switch statement, where you can again handle the error case however you wish.

Upvotes: 4

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