I'm getting a weird output in my rock paper scissors spock game

[ss1]

So I'm trying to create a rock paper scissors spock game where we use methods that display menu options to play the game, display the score, or quit, and checks for user validity. then the user inputs their choice, also asking for user validity. the computer throws a random choice and returns the value. then it's supposed to compare the two throws and returns who the winner is, and the scores are displayed.

import java.util.Scanner;
public class Project7 {
	public static void main(String[] args) {
		Scanner in = new Scanner (System.in);
		int displayMenu = 0;
		int displayweaponChoice = 0;
		do {
			displayMenu();
			boolean test = true;
			while (test) {
				if (in.hasNextInt()) {
					displayMenu = in.nextInt();
					test = false;
				} else { //user validity, i used the letter a
					System.out.println("Invalid Input");
					String dummy = in.next();

				}
			}
			String weapon ="";
			String computerThrow ="";

			switch (displayMenu) {

			case 1:
				displayweaponChoice();
				weaponChoice();

				computerThrow();

				compareChoices( );

				break;

			}

		} while (displayMenu!= 3);
	}


	public static void displayMenu () {
		Scanner in = new Scanner(System.in);
		System.out.println("1. Play Game");
		System.out.println("2. Show Score");
		System.out.println("3. Quit");			
	}

	public static void displayweaponChoice ( ) {
		Scanner in = new Scanner (System.in);
		int displayweaponChoice = 0;
		System.out.println("Choose your weapon");
		System.out.println("Enter R for Rock");
		System.out.println("Enter P for Paper");
		System.out.println("Enter S for Scissors");
		System.out.println("Enter L for Lizard");
		System.out.println("Enter O Spock");
		if (in.hasNextInt()) { //another user validity = i used a number here
			displayweaponChoice = in.nextInt();
			System.out.println("invalid input");
		}
		}
	public static void weaponChoice () {
		Scanner in = new Scanner (System.in);
		boolean test = true;
		String weaponChoice = in.nextLine();
		String weapon = in.nextLine();
		if (weaponChoice=="R") {
			weapon = "Rock";
		}
		if (weaponChoice == "P"){
			weapon ="Paper";
		}
		if (weaponChoice =="S") {
			weapon = "Scissors";
			
		}
		if (weaponChoice == "L"){
			weapon = "Lizard";
		}
		if (weaponChoice == "K") {
			weapon = "Spock";
		}
		System.out.println("You chose " + weaponChoice);
	}
		public static void computerThrow(){
			String computerThrow = "";
			double random = Math.random();
			int upperBound = 5; 
			int lowerBound = 1;
			int rand = (int) ((Math.random()*(upperBound - lowerBound +1)) +  lowerBound);
		if (rand == 1) {
			computerThrow = "Rock";
		}
		else if (rand == 2) {
			computerThrow = "Paper";
		}
			
		else if (rand == 3) {
			computerThrow = "Scissors";
		}
		else if (rand == 4) {
			computerThrow = "Lizard";
		}
		else if (rand==5){
			computerThrow = "Spock";
		}
		System.out.println("Computer chose " + computerThrow);
	}

	public static void compareChoices () {
		int winner=0;
		String computerThrow = "";
		String weapon ="";
		if (computerThrow==weapon) {
			winner = 0;
		}
		if (computerThrow == "Scissors" && weapon == "Paper") {
			winner = 1;
		}
		if (computerThrow=="Paper" && weapon =="Rock") {
			winner = 1;
		}
		if (computerThrow == "Rock" && weapon == "Lizard") {
			winner = 1; 
		}
		if (computerThrow == "Lizard" && weapon == "Spock") {
			winner = 1;
		}
		if (computerThrow == "Spock" && weapon=="Rock") {
			winner = 1;
		}
		if (computerThrow == "Rock" && weapon == "Paper") {
			winner = 1;
		}
		if (computerThrow == "Paper" && weapon == "Scissors") {
			winner = 1;
		}
		if(computerThrow == "Scissors" && weapon == "Lizard") {
			winner = 1;
		}
		if (computerThrow == "Lizard" && weapon == "Spock") {
			winner = 1;
		}
		if (computerThrow=="Spock"&& weapon=="Scissors") {
			winner = 1;
		}
		if (winner ==1) 
		{
			System.out.println("Computer won");
		}
		if (winner== 0) 
		{
			System.out.println("Tie");
		}
		if (winner == -2) 
		{
			System.out.println("Player won");
		} 
		
	
		
	}
		
	}

1. Play Game
2. Show Score
3. Quit
a
Invalid Input

1
Choose your weapon
Enter R for Rock
Enter P for Paper
Enter S for Scissors
Enter L for Lizard
Enter O Spock
R


You chose //Did not display the word "Rock"
Computer chose Lizard
Tie
1. Play Game
2. Show Score
3. Quit
1
Choose your weapon
Enter R for Rock
Enter P for Paper
Enter S for Scissors
Enter L for Lizard
Enter O Spock
3
invalid input
L

You chose L //doesn't display the actual word
Computer chose Lizard
Tie
1. Play Game
2. Show Score
3. Quit
1
Choose your weapon
Enter R for Rock
Enter P for Paper
Enter S for Scissors
Enter L for Lizard
Enter O Spock
P


You chose
Computer chose Paper
Tie // I'm getting a tie everytime, and it won't say whether or not the computer or the user won

1. Play Game
2. Show Score
3. Quit
2 //will not show score

1. Play Game
2. Show Score
3. Quit
3

[jammas615]

Firstly,

You chose L //doesn't display the actual word

You chose to print the input which is weaponChoice, it should just be weapon.

System.out.println("You chose " + weaponChoice);

[jammas615]

Also, a better way to decide who wins is by using a heirachy of 'weapons'. Assign each weapon a number and then compare the numbers, you then only need one or two controll statements, like:

int rock = 5;
int paper = 4;
int scissors = 3;
etc...
if (weapon > computerWeapon){
System.out.println("you win!");
}

if (weapon < computerWeapon){
System.out.println("you lose!");
}
else {
System.out.println("tie");
}

[Fubarable]

Also, a better way to decide who wins is by using a heirachy of 'weapons'. Assign each weapon a number and then compare the numbers, you then only need one or two controll statements, like:

int rock = 5;
int paper = 4;
int scissors = 3;
etc...
if (weapon > computerWeapon){
System.out.println("you win!");
}

if (weapon < computerWeapon){
System.out.println("you lose!");
}
else {
System.out.println("tie");
}

This may work for somethings but most definitely will not work for the logic of rock-paper-scissors, since there is no linear greater than or less than here, but rather a circular one: rock beats scissors, scissors beats paper and paper beats rock. If you wanted to do this more "esoterically" you could use an enum, and use a payoff matrix, but this is gross over-kill.

[Fubarable]

Also, to the original poster, don't use == to compare Strings. Instead use the equals method.

so this:

        if (computerThrow=="Paper" && weapon =="Rock") {
            winner = 1;
        }

should be this:

        if (computerThrow.equals("Paper") && weapon.equals("Rock")) {
            winner = 1;
        }

[Iron Lion]

What about if you create a class called RSPObject that implements Comparable?

class RSPObj implements Comparable {
    String name;
    RSPObj[] defeats; // doesn't need to be an array if it's just a standard 3-item game of RSP
    RSPObj[] losesTo; // ditto
    // constructor and getter/setter methods omitted
    public int compareTo(RSPObj obj) {
        // return 1 for object that it defeats, 0 for same object/tie, -1 for object that it loses to
    }
}
public class RSP {
    // declare and initialise RSPObj instances
    String[] outcomes = { "loses to", "ties with", "defeats" };
    public void play(RSPObj player1Choice, RSPObj player2Choice) {
        System.out.println(player1Choice.name + " "
                         + outcomes[player1Choice.compareTo(player2Choice) + 1] + " "
                         + player2Choice.name);
    }
}

[ss1]

I haven't learned arrays yet and if I used them I wouldn't get credit for it.......

[ss1]

Now when I pick a weapon the output looks like this:

Choose your weapon
Enter R for Rock
Enter P for Paper
Enter S for Scissors
Enter L for Lizard
Enter O Spock
R


You chose //will not display the word
Computer chose Scissors

Am I doing something wrong in the code?

public static void weapon() {
		Scanner in = new Scanner (System.in);
		String weapon = in.nextLine();
			   weapon = in.nextLine();
		if (weapon.equals("R")) {
			weapon = "Rock";
		}
		else if (weapon.equals ("P")) {
			weapon ="Paper";
		}
		else if (weapon.equals("S")) {
			weapon = "Scissors";
			
		}
		else if (weapon.equals ("L")) {
			weapon = "Lizard";
		}
		else if (weapon.equals("O")) {
			weapon = "Spock";
		}
		System.out.println("You chose " + weapon);
	}

[Iron Lion]

Why are you calling in.nextLine() twice?

[ss1]

Why are you calling in.nextLine() twice?

I've been used to doing that... so should I just say String weapon = in.nextLine?