"Choose a number between 0-9" game

Question

This is a simple "Choose a number between 0-9" Game. It works perfectly but I'd like to know if there's a way to make my code smaller with the exact same functionality.

package firstGame;

    import java.util.Scanner;

    public class Player {

        static Scanner p2Name = new Scanner(System.in);
        static Scanner p1Name = new Scanner(System.in);
        static Scanner p3Name = new Scanner(System.in);

        static Scanner p1Num = new Scanner(System.in);
        static Scanner p2Num = new Scanner(System.in);
        static Scanner p3Num = new Scanner(System.in);

        String name;
        int age;
        int size;

        public static void main(String[] args) {




            // Create a random number generator (0-9)
            int number = (int) (Math.random() * 10);

            // Get Player1's name
            System.out.print("Player 1, please enter your name : ");
            String p1 = p1Name.nextLine();
            System.out.println("Welcome " + p1 + "!");

            // Get Player1's chosen number
            System.out.println("Please enter a number between 0 and 9");
            int p1Choice = p1Num.nextInt();
            System.out.println("");

            // Get Player2's name
            System.out.print("Player 2, please enter your name : ");
            String p2 = p2Name.nextLine();
            System.out.println("Welcome " + p2 + "!");

            // Get Player2's chosen number
            System.out.println("Please enter a number between 0 and 9");
            int p2Choice = p2Num.nextInt();
            System.out.println("");

            // Get Player3's name
            System.out.print("Player 3, please enter your name : ");
            String p3 = p3Name.nextLine();
            System.out.println("Welcome " + p3 + "!");

            // Get Player3's chosen number
            System.out.println("Please enter a number between 0 and 9");
            int p3Choice = p3Num.nextInt();
            System.out.println("");

            //Output generated number
            System.out.println("The number I was thinking of was : " + number);

            //if 1 player wins, output this
            if (number == p1Choice || number == p2Choice || number == p3Choice) {
                System.out.println("We have a winner!");
            }

            //Player1 won or lost?
            if (number == p1Choice) {
                System.out.println(p1 + " won!");
            } else {
                System.out.println(p1 + ", you lose!");
            }

            //Player2 won or lost?
            if (number == p2Choice) {
                System.out.println(p2 + " won!");
            } else {
                System.out.println(p2 + ", you lose!");
            }

            //Player3 won or lost?
            if (number == p3Choice) {
                System.out.println(p3 + " won!");
            } else {
                System.out.println(p3 + ", you lose!");
            }

        }

    }

Answer 1

        static Scanner p2Name = new Scanner(System.in);
        static Scanner p1Name = new Scanner(System.in);
        static Scanner p3Name = new Scanner(System.in);

        static Scanner p1Num = new Scanner(System.in);
        static Scanner p2Num = new Scanner(System.in);
        static Scanner p3Num = new Scanner(System.in);

You don't need all those scanners. One is plenty.

        static Scanner scanner = new Scanner(System.in);

Then replace each call using one of the other variables with scanner.

It's possible that you may have to call scanner.nextLine() after calling scanner.nextInt(). I haven't tried it.

@BKSpurgeon in Java

Here's the @BKSpurgeon solution converted to Java:

Program.java

class Program {

    public static void main(String[] args) {
        GameMaster g = new GameMaster(3);
        g.printResults();
    }

}

Player.java

class Player {

    static Scanner scanner = new Scanner(System.in);

    private String name;       
    private int number;

    public Player(int playerPosition) {
        name = inputName(playerPosition);
        printName();
        number = inputNumber();
        //scanner.nextLine(); // uncomment if needed
    }

    private void printName() {
        System.out.println("Welcome "+ name + "!");
    }

    private int inputNumber() {
        System.out.println("Please enter a number between 0 and 9");

        return scanner.nextInt();
    }

    private String inputName(int playerPosition) {
        System.out.println("Player " + playerPosition + ", please enter your name");

        return scanner.nextLine();
    }

    public String calculateResult(int winningNumber) {
        return name + ((winningNumber == number) ? " won!" : ", you lose!");
    }

}

GameMaster.java

public class GameMaster {

    private final int winningNumber;
    private final List<Player> players = new ArrayList<>();

    public GameMaster(int playerCount) {
        winningNumber = chooseWinningNumber();

        for (int i = 1; i <= playerCount; i++) {
            players.add(new Player(i));
        }
    }

    public void printResults() {
        for (Player p : players) {
            System.out.println(p.calculateResult(winningNumber));
        }
    }

    private static int chooseWinningNumber() {
        return (int) (Math.random() * 10);
    }

}

I made a few tweaks to comply with Java coding conventions, but the structure is mostly the same.

I haven't tried to run it, so beware of typos, etc.

Answer 2

The first issue I see with the code is that there is a lot of (needless) repetition.

• All the players are being asked to enter a name: the code to do this need only be written once, in one place.

• Same issue with number: enter and storage code need only be done once.

• We can store that functionality in a Player class – so every time we create a player it does those same repetitive things. But each player might choose a different number. So that unique value should be saved within an instance of a player class.

• The issue about winning/losing can be taken care of by a GameMaster.

Normally i'd go with TDD but i thought i could do it faster without it. it's worth noting how most of the duplication is eliminated. a die hard OOP might say: but you have conditionals in your PrintResults method!! they'd be right too, but it's probably a lot simpler to leave it in there.

I hope this helps you. From your point of view it's well worth redoing it with TDD (test driven development). btw it's a c#. i know you wrote in Java but who can really tell the difference between the two anyways?

    class Program
    {
        static void Main(string[] args)
        {
            GameMaster g = new GameMaster();
            g.PrintResults();
        }
    }

 class Player
    {
        private string _name;       

        private int winningNumber;

        private int _number;

        public Player(int playerPosition, int winningNumber)
        {
            this.winningNumber = winningNumber;

            _name = GetName(playerPosition);
            PrintName();
            _number = GetNumber();            
        }

        private void PrintName()
        {
            Console.WriteLine("Welcome "+ _name + "!");
        }

        /// <summary>
        /// Gets player's number choice. Note that I have not added
        /// any exception handling. What if a player decides to choose 11?
        /// that is outside the acceptable boundary. There is currently
        /// no way to handle this.
        /// </summary>
        /// <returns></returns>
        private int GetNumber()
        {
            Console.WriteLine("Please enter a number between 0 and 9");
            int _number = Convert.ToInt32(Console.ReadLine());

            return _number;
        }

        private string GetName(int playerPosition)
        {
            Console.WriteLine("Player " + playerPosition + "Please enter your name");
            string name = Console.ReadLine();

            return name;
        }

        public void PrintResult()
        {
            if (this.winningNumber == _number)
            {
                Console.WriteLine(_name + " won!");

            }
            else
            {
                Console.WriteLine(_name + ", you lose!");
            }

            Console.ReadLine();
        }
    }

public class GameMaster
    {
        int winningNumber;

        List<Player> players;

        public GameMaster()
        {
            // get winning number
            this.winningNumber = GetWinningNumber();
            this.players = GetPlayers();
        }

        public void PrintResults()
        {
            foreach (Player p in players)
            {
                p.PrintResult();
            }
        }

        private List<Player> GetPlayers()
        {
            List<Player> players = new List<Player>();

            for (int i = 1; i < 4; i++)
            {
                Player a = new Player(i, winningNumber);
                players.Add(a);
            }

            return players;
        }

        private int GetWinningNumber()
        {
            Random rnd = new Random();
            int number = rnd.Next(0, 10);
            return number;
        }
    }