Question

My assignment instructions are “rolling” 2 dice and getting the sum and then finding the probability that that sum came up based on how many times the user wants to roll the die. I must use a nested loop and I can’t use separate loops for each dice combination (which I haven’t done). I am not allowed to use arrays in this assignment.

Write a program to simulate tossing a pair of 11-sided dice and determine the percentage of times each possible combination of the dice is rolled.

1. Create a new project called 5.05 Random Dice in the Mod05 Assignments folder.
2. Create a class called DiceProbability in the newly created project folder.
3. Ask the user to input how many times the dice will be rolled.
4. Calculate the probability of each combination of dice. (You may want to start with more familiar six-sided dice.)
5. Print the results neatly in two columns

I need help in finding out what I put into the second “for” loop. Sorry for the messy list of integers and if statements. The code is unfinished.

import java.util.Random;
import java.util.Scanner;
public class DiceProbability
{
public static void main(String[] args)
{
    Scanner in = new Scanner(System.in);
    Random randNum = new Random();

    int count2 = 0;
    int count3 = 0;
    int count4 = 0;
    int count5 = 0;
    int count6 = 0;
    int count7 = 0;
    int count8 = 0;
    int count9 = 0;
    int count10 = 0;
    int count11= 0;
    int count12= 0;
    int count13 = 0;
    int count14 = 0;
    int count15 = 0;
    int count16 = 0;
    int count17 = 0;
    int count18 = 0;
    int count19 = 0;
    int count20 = 0;
    int count21 = 0;
    int count22 = 0;
    int die1 = 0, die2 = 0;
    int rolls = 0;
    int actualDiceSum;
    double probabilityOfDice = 0.0;

    System.out.print("Number of Rolls: ");
    rolls = in.nextInt();

    for(int timesRolled = 0; timesRolled < rolls; timesRolled++)
        {
        die1 = randNum.nextInt(12);
        die2 = randNum.nextInt(12);
        actualDiceSum = die1 + die2;
        for()
        {
            if(actualDiceSum == 2){
            count2++;
            probabilityOfDice = count2 / rolls;
            }
            else if(actualDiceSum == 3){
            count3++;
            probabilityOfDice = count3 / rolls;
            }
            else if(actualDiceSum == 4){
            count4++;
            probabilityOfDice = count4 / rolls;
            }
            else if(actualDiceSum == 5){
            count5++;
            probabilityOfDice = count5 / rolls;
            }
            else if(actualDiceSum == 6){
            count6++;
            probabilityOfDice = count6 / rolls;
            }
            else if(actualDiceSum == 7){
            count7++;
            probabilityOfDice = count7 / rolls;
            }
            else if(actualDiceSum == 8){
            count8++;
            probabilityOfDice = count8 / rolls;
            }
            else if(actualDiceSum == 9){
            count9++;
            probabilityOfDice = count9 / rolls;
            }
            else if(actualDiceSum == 10){
            count10++;
            probabilityOfDice = count10 / rolls;
            }
            else if(actualDiceSum == 11){
            count11++;
            probabilityOfDice = count11 / rolls;
            }
            else if(actualDiceSum == 12){
            count12++;
            probabilityOfDice = count12 / rolls;
            }
            else if(actualDiceSum == 13){
            count13++;
            probabilityOfDice = count13 / rolls;
            }
            else if(actualDiceSum == 14){
            count14++;
            probabilityOfDice = count14 / rolls;
            }
            else if(actualDiceSum == 15){
            count15++;
            probabilityOfDice = count15 / rolls;
            }
            else if(actualDiceSum == 16){
            count16++;
            probabilityOfDice = count16 / rolls;
            }
            else if(actualDiceSum == 17){
            count17++;
            probabilityOfDice = count17 / rolls;
            }
            else if(actualDiceSum == 18){
            count18++;
            probabilityOfDice = count18 / rolls;
            }
            else if(actualDiceSum == 19){
            count19++;
            probabilityOfDice = count19 / rolls;
            }
            else if(actualDiceSum == 20){
            count20++;
            probabilityOfDice = count20 / rolls;
            }
            else if(actualDiceSum == 21){
            count21++;
            probabilityOfDice = count21 / rolls;
            }
            else if(actualDiceSum == 22){
            count22++;
            probabilityOfDice = count22 / rolls;
           }
        }
    }


    System.out.println("Sum of Dice \t\t Probability");
    System.out.println("2's\t\t" + probabilityOfDice + "%");
    System.out.println("3's\t\t" + probabilityOfDice + "%");
    System.out.println("4's\t\t" + probabilityOfDice + "%");
    System.out.println("5's\t\t" + probabilityOfDice + "%");
    System.out.println("6's\t\t" + probabilityOfDice + "%");
    System.out.println("7's\t\t" + probabilityOfDice + "%");
    System.out.println("8's\t\t" + probabilityOfDice + "%");
    System.out.println("9's\t\t" + probabilityOfDice + "%");
    System.out.println("10's\t\t" + probabilityOfDice + "%");
    System.out.println("11's\t\t" + probabilityOfDice + "%");
    System.out.println("12's\t\t" + probabilityOfDice + "%");
    System.out.println("13's\t\t" + probabilityOfDice + "%");
    System.out.println("14's\t\t" + probabilityOfDice + "%");
    System.out.println("15's\t\t" + probabilityOfDice + "%");
    System.out.println("16's\t\t" + probabilityOfDice + "%");
    System.out.println("17's\t\t" + probabilityOfDice + "%");
    System.out.println("18's\t\t" + probabilityOfDice + "%");
    System.out.println("19's\t\t" + probabilityOfDice + "%");
    System.out.println("20's\t\t" + probabilityOfDice + "%");
    System.out.println("21's\t\t" + probabilityOfDice + "%");
    System.out.println("22's\t\t" + probabilityOfDice + "%");
}
}

Answer 1

Well according to me you don’t require 2nd for loop.
Every time a dice is rolled you calculate the the sum and increase the count according to the sum.

you would require to use separate variables for calculating the probability of each sum.

For example

Probability of count2 = (count2/number of rolls);
Probability of count3 = (count2/number of rolls);

Use separate variables for probability of counts

try this code

import java.util.Random;
import java.util.Scanner;
public class DiceProbability
{
public static void main(String[] args)
{
    Scanner in = new Scanner(System.in);
    Random randNum = new Random();
int count2 = 0;
int count3 = 0;
int count4 = 0;
int count5 = 0;
int count6 = 0;
int count7 = 0;
int count8 = 0;
int count9 = 0;
int count10 = 0;
int count11= 0;
int count12= 0;
int count13 = 0;
int count14 = 0;
int count15 = 0;
int count16 = 0;
int count17 = 0;
int count18 = 0;
int count19 = 0;
int count20 = 0;
int count21 = 0;
int count22 = 0;
int die1 = 0, die2 = 0;
int rolls = 0;
int actualDiceSum;
double probabilityOfDice = 0.0;

System.out.print("Number of Rolls: ");
rolls = in.nextInt();

for(int timesRolled = 0; timesRolled < rolls; timesRolled++)
    {
    die1 = randNum.nextInt(12);
    die2 = randNum.nextInt(12);
    actualDiceSum = die1 + die2;

        if(actualDiceSum == 2){
        count2++;

        }
        else if(actualDiceSum == 3){
        count3++;

        }
        else if(actualDiceSum == 4){
        count4++;

        }
        else if(actualDiceSum == 5){
        count5++;

        }
        else if(actualDiceSum == 6){
        count6++;

        }
        else if(actualDiceSum == 7){
        count7++;

        }
        else if(actualDiceSum == 8){
        count8++;

        }
        else if(actualDiceSum == 9){
        count9++;

        }
        else if(actualDiceSum == 10){
        count10++;

        }
        else if(actualDiceSum == 11){
        count11++;

        }
        else if(actualDiceSum == 12){
        count12++;

        }
        else if(actualDiceSum == 13){
        count13++;

        }
        else if(actualDiceSum == 14){
        count14++;

        }
        else if(actualDiceSum == 15){
        count15++;

        }
        else if(actualDiceSum == 16){
        count16++;

        }
        else if(actualDiceSum == 17){
        count17++;

        }
        else if(actualDiceSum == 18){
        count18++;

        }
        else if(actualDiceSum == 19){
        count19++;

        }
        else if(actualDiceSum == 20){
        count20++;

        }
        else if(actualDiceSum == 21){
        count21++;

        }
        else if(actualDiceSum == 22){
        count22++;

       }
    }
}


System.out.println("Sum of Dice \t\t Probability");
System.out.println("2's\t\t" + count2/rolls + "%");
System.out.println("3's\t\t" + count3/rolls + "%");
System.out.println("4's\t\t" + count4/rolls + "%");
System.out.println("5's\t\t" + count5/rolls + "%");
//and so on...
}
}