Thread: Calculate median dice game HELP!

Hello,

I am a beginner programmer in Java. I got stuck with one of the exercises and do not understand what could be wrong.
I cannot find out what is the issue with my median calculation....

My program should roll one dice (1-6) number of times. The program shall then collect how many of each dice value was computed.
The program should also calculate average value and median value. The output should look like:

Number of rolls :

xxx times of dice value 1
xxx times of dice value 2
xxx times of dice value 3
xxx times of dice value 4
xxx times of dice value 5
xxx times of dice value 6

Average:

Median:

Here is my code:

import java.util.Arrays;
import java.util.Scanner;
 
public class DiceGame
{
public static void main (String[] args) 
{
 
Scanner inputReader = new Scanner(System.in);
 
//Array or each dice value
int[] number = new int[]{1, 2, 3, 4, 5, 6};
 
//Array for collecting number of each dice value
int[] counter = new int[6]; 
 
//number of executions:
int exec = 11;
 
//Array to calculate median
int[] medianArray = new int[exec];
 
// Variables needed to calculate median and average values
double sum = 0;
double average = 0;
double median = 0;
 
//Prints how many executions 
System.out.println("Number of rolls" + exec);
 
for(int i =0 ;  i < exec ; i++)
{
    //Roll the dice
    int dice=(int)(Math.random()*6);
 
    //For each roll count each value
    counter[dice]++;
 
    //For each roll store result in Array
    medianArray[i] = dice;
 
}
 
for(int j = 0 ; j < 6 ; j++)
{
    System.out.println(counter[j]+" times of dice value "+number[j]);
    sum = sum + (counter[j] * number[j]);
}
 
average = sum / exec;
System.out.println("Average " + average);
 
// Sort medianArray:
Arrays.sort (medianArray);
 
//If number of elements are an even number:
if (medianArray.length % 2 == 0)
{
    median = (medianArray[medianArray.length/2] + 
             medianArray[(medianArray.length/2) +1])
             /2;
 
    System.out.println("Median "+ median);
}
 
//Otherwise the median value is in the middle:
else
{
    median = medianArray[((medianArray.length)/2)];
    System.out.println("Median "+ median);
}
 
}
}

Output looks like:

Number of rolls11
3 times of dice value 1
0 times of dice value 2
2 times of dice value 3
2 times of dice value 4
2 times of dice value 5
2 times of dice value 6
Average 3.5454545454545454
Median 3.0

The meedian value is not correct, it should be the 6th value in the sorted medianArray, in other words value 4.
What could be wrong in my code?

Can you copy the program's output and paste it here so we can see what you are asking about?
Please add comments to the output to describe what is wrong with it and show what the desired output is.

Please edit your post and wrap your code with code tags:

[code]
**YOUR CODE GOES HERE**
[/code]

to get highlighting and preserve formatting.

The meedian value is not correct,

What is the correct formula for computing the median value? Does your code use that formula?

the latter don't work

Why do you think your value is wrong?

Since the medianArray consists of index 11, the median valus is in the middle, hence:

median = medianArray[((medianArray.length)/2)];

Why isn't that code executed?

Is that the only change that the code needs? I get this exception with that simple change:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 6

Upon reviewing your code, I noticed a small error that might be causing the incorrect median value. In the if statement where you calculate the median for an even number of elements, change (medianArray.length/2) + 1 to (medianArray.length/2) - 1. This adjustment will ensure you access the correct index in the sorted medianArray.
Once you make this change, give your code another try and see if the median calculation comes out as expected. Remember, programming is all about learning and improving over time, so don't worry if you encountered a small hiccup.
By the way, if you ever need to roll a d12 or any other dice for testing or fun, you can use the Dice Roller tool at https://flipsimu.com/dice-roller/roll-d12/. It's a handy resource for generating random dice rolls and adding some excitement to your projects.

It sounds like you're working on an interesting Java program. Calculating the median of dice rolls can be a bit tricky, but I'm sure we can figure it out.
To help you better, it would be great if you could share some of your code or let us know specifically where you're getting stuck. That way, we can provide more targeted assistance.
By the way, if you're into programming and looking to make some extra money, you might want to explore Apps That Pay You Real Money. It's a handy resource for finding apps that offer opportunities to earn while you pursue your coding interests.