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Thread: Help Improve My Rock,Paper,Scissors

  1. #1
    Member Emperor_Xyn's Avatar
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    Default Help Improve My Rock,Paper,Scissors

    Well I finally had the logic to make a rock paper scissors, but i'm very sure i'm taking long steps.

    Heres the code:
    /*
     * To change this template, choose Tools | Templates
     * and open the template in the editor.
     */
    package rps;
    import java.util.*;
     
    public class RPS {
     
    static int x;  
    static boolean ock=false;
    static boolean aper=false;
    static boolean cissors=false;
     
        public static void main(String[] args) {
            rock da = new rock();
           da.say();
     
     
           for (int x=0;x<5;x=x+1){
           double crn = Math.random()*10;
          if(crn>7){
              ock=true;}
           if(crn>3&&crn<7){
               aper=true;}
     
          if(crn>0&&crn<3){
               cissors=true;
           }
     
     
           Scanner keyboard = new Scanner(System.in);
           String choice = keyboard.next();
     
     
     
     
     
           if (choice.equals("rock")){
               if(ock){
                   System.out.println("Computer picked rock, you tie.");
               }
               if(aper){
                   System.out.println("Computer picked paper, you lose!");
               }
                if(cissors){
                   System.out.println("Computer picked scissors, you win!");
               }
           }
        if (choice.equals("paper")){
               if(ock){
                   System.out.println("Computer picked rock, you win.!");
               }
               if(aper){
                   System.out.println("Computer picked paper, you tie!");
               }
                if(cissors){
                   System.out.println("Computer picked scissors, you win!");
               }
           }
     
             if (choice.equals("scissors")){
               if(ock){
                   System.out.println("Computer picked rock, you lose.");
               }
               if(aper){
                   System.out.println("Computer picked paper, you win!");
               }
                if(cissors){
                   System.out.println("Computer picked scissors, you tie!");
               }
           }
           }
     
        }}

    Question 1: How can I improve the randomization of 3 different possibilities.

    Question 2: How can I improve all the if statements, just throw out some google keywords if you like.


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Help Improve My Rock,Paper,Scissors

    randomization of 3 different possibilities
    Do you want the 3 possibilities equally likely? Your code does not generate equally likely outcomes.

    Write a loop for 1000 times and count each of the outcomes with your code and print out the three counts. Then change the logic so the three outcomes are nearly equal.

  3. #3
    Member Emperor_Xyn's Avatar
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    Default Re: Help Improve My Rock,Paper,Scissors

    Quote Originally Posted by Norm View Post
    Do you want the 3 possibilities equally likely? Your code does not generate equally likely outcomes.
    Yes, norm, exactly. I'm guessing somewhere in the vast supply of API, there's a method already made that can do something like this? I just don't know it other than making Math.random();

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    Default Re: Help Improve My Rock,Paper,Scissors

    Question 1: How can I improve the randomization of 3 different possibilities.
    There is a package called java.util.Random that will help you with pseudo-random numbers. In particular, check out nextInt(n).

    You can easily use this to generate a random integer in a given range. Just be sure to check out what 'seeding' a random number generator means (google), otherwise you will get the same set of results each time you run the program.

    Personally, I prefer to generate a full random primitive and use the modulo operator to trim it to size (read up on modulo because it is useful for all kinds of reasons).

    Question 2: How can I improve all the if statements, just throw out some google keywords if you like.
    You could have used string concatenation to solve this without so much typing. Consider, you only need one little bit of logic to say "Computer choose xxx" and another separate bit of logic to say "you win" or "you loose". Semantically this way is identical to the way you have done it but it is cleaner and displays a better understanding of logic.

    A good exercise here would be turn the check for win/loss into a function that returns true/false. Also, I would take a look at the many, many ways in which this code can fail:

    if (choice.equals("rock"))


    What if I type "Rock" or " rock" or "rock " or "rrock". I would go for a menu choice where the user has to press '1' '2' or '3' and asks them to try again if the input is bad.

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