CODEWITHSUNDEEP
javawhile-loop
Ih8th3c0ld
Ih8th3c0ld

Reputation: 3

Exit While loop from String input

So I am writing a user menu using a simple while loop and case breaking but having an issue. I need to use chars instead of ints for my cases (really using a string Scanner for simplicity) and for the most part it works. But when I enter D (my exit case) the loop does not break. Not sure why, I have done this with ints many times without an issue...

import java.util.Scanner;

public class Postfix_Notation {
 public static void main(String[] args) {
  Scanner scanner = new Scanner(System.in);
  String choice = "Z";

  while (choice != "D") {
   System.out.println("Enter A, B  or C to perform an operation or enter D to exit.");
   System.out.println("A- Evaluate a user input postfix expressions");
   System.out.println("B- Convert, display infix expressions to postfix expressions then evaluate and display the result of thepostfix expression");
   System.out.println("C- Reads words from a the text file (hangman.txt) in a LinkedList and use an iterator on it to displays all the words (duplicates allowed) in descending alphabetical order");
   System.out.println("D- Exit");
   choice = new Scanner(System.in).next();

   switch (choice) {
    case "A":
     System.out.println("Enter a string: ");
     String s = new Scanner(System.in).next();
     System.out.println("All possible permutations of " + s + " are: ");
     System.out.println("\n");
     break;

    case "B":
     Scanner input2 = new Scanner(System.in);

     System.out.println("Enter a hex string: ");
     String hexString = input2.next();

     System.out.println("The decimal equivalent of " + hexString + " is " + (hexString));
     System.out.println("\n");
     break;

    case "C":
     Scanner input = new Scanner(System.in);

     System.out.println("Enter a binary string: ");
     String binaryString = input.next();

     System.out.println("The decimal equivalent of " + binaryString + " is " + (binaryString));
     System.out.println("\n");
     break;

    case "D":

     System.out.println("Program Ended");

     break;

    default:
     System.out.println("Invalid Input");
   }
  }
 }
}

Upvotes: 0

Views: 2436

Answers (1)

Michu93
Michu93

Reputation: 5689

So while(!choice.equals("D")) do the job. Check this link: How do I compare strings in Java?. You compared references instead of values.

Upvotes: 1

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