Question

Possible Duplicate:
How do I compare strings in Java?

I wrote a program that will “roll dice” and tell you how many turns it takes to get yahtzee. This works, but there is a problem when it asks you to go again. It will keep giving me an “Invalid input”, when in fact I enter something that should exit the loop. Here is my code, the loop goes from lines 24-34 but I’ll put all of it just in case it is a problem earlier on.

import java.util.Scanner;
import java.util.Random;

public class Yahtzee {

public static void main(String[] args){

    int d[] = {0,0,0,0,0};
    int x = 0;
    Scanner s = new Scanner(System.in);
    Random r = new Random();

    while (1!=0){
        d[0] = r.nextInt(6);
        d[1] = r.nextInt(6);
        d[2] = r.nextInt(6);
        d[3] = r.nextInt(6);
        d[4] = r.nextInt(6);
        x+=1;

        if (d[0]==d[1] && d[0]==d[2] && d[0]==d[3] && d[0]==d[4]) {
            System.out.println("You got yahtzee, every dice showed " + Integer.toString(d[0]));
            System.out.println("It only took " + Integer.toString(x) + " turns");
            while (1!=3) {
                System.out.print("Go again? y/n: ");
                String ans = s.nextLine();
                if (ans.toLowerCase()=="n"){
                    System.exit(0);
                } else if (ans.toLowerCase()=="y") {
                    break;
                } else {
                    System.out.println("Invalid input!");
                }
            }

        }   
    }   
}   
}

I honestly cannot figure this out, although it is probably incredibly obvious. Where is the problem?

Answer 1

Use .equals to compare strings, rather than the equality operator ==.

if (ans.toLowerCase().equals("n")){
    System.exit(0);
} else if (ans.toLowerCase().equals("y")) {

The equality operator checks only that their memory location is equal, which it is not in this case.