Issue with logic and Loop in Java

Question

I started coding small program in Java. I wanted to exercise try-catch block, but i did not even come to that part and got stuck on loop part. I know this is very basic loop

Answer 1

You need a logical and (not or) here

while (choice != 1 || choice != 2) {
    System.out.println("Invalid entry, press 1 or 2");
    MenuLoop();
} 

should be something like

while (choice != 1 && choice != 2) {
    System.out.println("Invalid entry, press 1 or 2");
    MenuLoop();
} 

or (using De Morgan's laws) like

while (!(choice == 1 || choice == 2)) {
    System.out.println("Invalid entry, press 1 or 2");
    MenuLoop();
} 

Answer 2

This is a logical problem, the "choice" value should be either 1 or 2. In your (while) statement you are checking that "choice" is not different from 1 but also that "choice" is not different from 2. This condition is never reached because "choice" can be either 1 or 2 but not both values at the same time. This is only an explanation of the situation.

Answer 3

Maybe you can try the following code. In your code , it's not need to use iteration.

choice = input.nextInt();
while (choice != 1 && choice != 2) {
    System.out.println("Invalid entry, press 1 or 2");
    choice = input.nextInt();
}   

Answer 4

Part of the problem is that you are recursively calling menuLoop from within menuLoop

If you had a while loop within main then you could just do a return if the proper keys is not pressed.

so main would be something like

while (!menuLoop () {
  System.out.println("Invalid entry, press 1 or 2");
}

and menuLoop would return a boolean

public static boolean MenuLoop() {

  ....

System.out.println("1. Check for Number 1");
System.out.println("2. Check for Number 2");
System.out.print("Please enter your choice... ");
choice = input.nextInt();
if(choice != 1 && choice != 2) {   // and NOT or
    return false;
}    

switch (choice) {
case 1:
    System.out.println("Pressed 1");
    break;
case 2:
    System.out.println("Pressed 2");
    break;
default:
    System.out.println("Invalid number");
}
return true;

Also please remember that the scanner.nextInt will not swallow up the Enter that may or may not be pressed.