Question

Java

CSC252   Programming II   
Static Methods, Enums, Constants, Random

Rock Paper Scissors

Write a program that allows the user to play "Rock, Paper, Scissors".

Write the RPS class. All code should be in one file.

main() will be part of the RPS class, fairly small, and contain only a loop that asks the user if they want to play "Rock, Paper, Scissors". If they say yes, it calls the static method play() of the RPS class. If not, the program ends.

play() has no parameters, and no return value. (In this exercise, the class RPS does contain code that will input and output to the user.) Use GUI for all input and output. Note that since play() is a static method, it can be called directly on the RPS class -- main() should not instantiate an RPS object. play() will allow one full game of RPS to run. To win an RPS game, the player or the computer must win 2 out of 3 rounds.

The following should all be done inside the RPS class:

• Decide how the user will input rock, paper or scissors: character? string? integer?
  Prompt the user to input rock, paper, or scissors.
• Use simple constants (static final) to represent ROCK, PAPER, and SCISSORS.
• Use enums to represent WIN, LOSE, TIE. (This is the result of each round.)
• Use the Random class to generate random computer choices. (Don’t use Math.random).
• For each round, print out what the player threw, what the computer threw, and who won or if there was a tie. In RPS, Rock beats Scissors, Scissors beats Paper, and Paper beats Rock. Optimize your code so that you are testing as few cases as possible, but covering all the possible combinations.
• Keep track of the number of rounds that the player has won and the computer has won.
• When someone wins the game (wins 2 rounds), print out a message indicating whether the player or the computer has won, and return to main().

Answer 1

The java code is as follows :

import java.util.*;

enum State
{
   WIN, LOSE, TIE;
}

class RPS
{
   //Constants to represent rock, paper and scisoors
   protected static final int ROCK = 1;
   protected static final int PAPER = 2;
   protected static final int SCISSORS = 3;

   protected static State playerState;

   public static void play()
   {
       Random ran = new Random();
       Scanner in = new Scanner(System.in);

       int playerChoice;
       int CPUChoice;

       int playerWonCount = 0;
       int CPUWonCount = 0;

       System.out.println("Welcome to Rock, Paper, Scissors!!");

       for (int i = 0; i < 3; i++)
       {
           System.out.println("\nRound : " + (i + 1) + " - ");

           System.out.print("Enter " + RPS.ROCK + " for rock, " + RPS.PAPER + " for paper, and " + RPS.SCISSORS + " for scisoors :- ");
           playerChoice = in.nextInt();

           CPUChoice = ran.nextInt(3) + 1;

           System.out.print("\nYou choose : ");
           if (playerChoice == RPS.ROCK)
               System.out.println("Rock");
           else if (playerChoice == RPS.PAPER)
               System.out.println("Paper");
           else
               System.out.println("Scissors");

           System.out.print("CPU choose : ");
           if (CPUChoice == RPS.ROCK)
               System.out.println("Rock");
           else if (CPUChoice == RPS.PAPER)
               System.out.println("Paper");
           else
               System.out.println("Scissors");

           if (playerChoice == CPUChoice)
               System.out.println("\nIts a tie!!");
           else if ( (playerChoice == RPS.PAPER && CPUChoice == RPS.ROCK) || (playerChoice == RPS.ROCK && CPUChoice == RPS.SCISSORS)
               || (playerChoice == RPS.SCISSORS && CPUChoice == RPS.PAPER) )
           {
               System.out.println("\nYou won the round!!");
               playerWonCount++;
           }
           else
           {
               System.out.println("\nCPU won the round!!");
               CPUWonCount++;
           }
       }

       if (CPUWonCount == playerWonCount)
           RPS.playerState = State.TIE;
       else if (CPUWonCount > playerWonCount)
           RPS.playerState = State.LOSE;
       else
           RPS.playerState = State.WIN;

       switch(RPS.playerState)
       {
           case TIE :
               System.out.println("\n\nThe game was a tie!!\n");
               break;
           case WIN :
                   System.out.println("\n\nYou won the game!!\n");
               break;
           case LOSE :
                   System.out.println("\n\nCPU won the game\n");
               break;
       }
   }

   public static void main(String args[])
   {
       char ch = ' ';
       Scanner in = new Scanner(System.in);

       while(true)
       {
           System.out.print("Do you want to play(y/n) : ");
           ch = in.next().charAt(0);

           if (ch != 'n' && ch != 'N')
               RPS.play();
           else break;
       }

       System.out.println("\n\nGame Ended!!");
   }

}

OUTPUT :

Do you want to play y/n) : y Welcome to Rock, Paper, Scissors!! Round : 1 - Enter 1 for rock, 2 for paper, and 3 for scisoors :- 3 You choose : Scissors CPU choose : Scissors Its a tie!! Round : 2 - Enter 1 for rock, 2 for paper, and 3 for scisoors :- 2 You choose : Paper CPU choose : Scissors CPU won the round! ! Round : 3 - Enter 1 for rock, 2 for paper, and 3 for scisoors :- 1 You choose : Rock CPU choose : Scissors You won the round! ! The game was a tie!! Do you want to play(y/n) : 0 Game Ended!!