创建一个基本菜单，为什么我做对了？ -Java

Question

I'm taking an Intro to Java class, and I haven't been having any trouble until now. I don't know if I'm just being a fool and the answer is simple but here goes.

I need to create a simple menu. I prompt the user, and then they enter an integer to choose one option. But there also needs to be an option to type "X" and exit the program.

Scanner in = new Scanner(System.in);
    System.out.println("Welcome to the Math Study Guide!");
    System.out.println("Which arithmetic table would you like to use?");
    System.out.println("1) Addition");
    System.out.println("2) Subtraction");
    System.out.println("3) Multiplication");
    System.out.println("4) Division");
    System.out.println("X) Exit the program");
    int input = in.nextInt();


    if (input <= 5 )
        {if (input == 1){System.out.println("Addition");}
        {if (input == 2){System.out.println("Subtraction");}
        {if (input == 3){System.out.println("Multiplication");}
        {if (input == 4){System.out.println("Division");}

    else {System.out.println("You have exited");}

Testing it, whenever I type "X" it shuts down everything and doesn't tell me I've exited. Is there a general input I can use where you can enter either an int or a String?

Answer 1

As already stated in some comments, your probleme is the data-type. If someone enters 'X' in the program, it is expected to be an integer value, which it is not.

To get your Program working you need to alter your datatype from int to String

String input = in.next();

this will get you the input.

Now make a switch/case instead of your if-statements

switch (input) {
    case "1" : System.out.println("Addition");
    break;
    case "2" : System.out.println("Subtraction");
    break;
    deafult: System.out.println("You have exited the program");
    break;
}

If you are not familiar with the switch/case statement: case "1" checks if input equals "1". If true it prints out "Addition", after that it is important to make a break; otherwise it would go on checking if input equals "2" and so on. the default branch is activated if nothing else matches. So your program would also write "You have exited the program" if your input was eg "r". If you don't want that, just add another case "x" and write your thing.