Question

Hopefully this is a quick question. I’m making a simple rock paper scissors game. I make a random computer choice fine, and get the user’s choice fine. But when I try to find who wins, it prints the last else in my else if block that is for invalid input.

It prints “Enter a valid choice” when a correct choice has been made.

import java.util.Random;
import javax.swing.JOptionPane;

public class JavaApplication4 {

    public static void main(String[] args) 
    {
        Random ranNums = new Random();

        int comp = ranNums.nextInt(3);
        String comp2;
        String winner;

        String user = JOptionPane.showInputDialog
                (null, "Enter rock, paper, or scissors");
        user.toLowerCase();

        if(comp == 0)
            comp2 = "rock";
        else if(comp == 1)
            comp2 = "paper";
        else 
            comp2 = "scissors";

        //Computer wins
        if(comp2 == "rock" && user == "scissors")
            winner = "The computer wins";

        else if(comp2 == "paper" && user == "rock")
            winner = "The computer wins";    

        else if(comp2 == "scissors" && user == "paper")
            winner = "The computer wins";

        //Tie game
        else if(comp2 == "rock" && user == "rock")
            winner = "It's a tie";

        else if(comp2 == "paper" && user == "paper")
            winner = "It's a tie";

        else if(comp2 == "scissors" && user == "scissors")
            winner = "It's a tie";

        //User wins
        else if(comp2 == "scissors" && user == "rock")
            winner = "You win!";

        else if(comp2 == "rock" && user == "paper")
            winner = "You win!";

        else if(comp2 == "paper" && user == "scissors")
            winner = "You win!";
        else
            winner = "Enter a valid choice";

        JOptionPane.showMessageDialog(null, "You picked " + user + "\n" +
            "The computer picked " + comp2 + "\n" +
                winner);



    }
}

Answer 1

you can’t use

comp == "paper" 

to compare strings in java. You use

comp.equals("paper")

or if case doesn’t matter

comp.equalsIgnoreCase("paper")