Question

Write a program in Java that creates an array of doubles. The array must have size 1000. Fill this array with random numbers between 0 and 1. Then compute and print the total value of all the elements of the array, the mean, the minimum, and the maximum.

Filling the array with random numbers must be done by a method that you define and implement. Computing and printing the statistics must be done by another method, which again you must define and implement. This second method must use an enhanced for loop.

Answer 1

Source code of the program and its working are given below.Comments are also given along with the code for better understanding.Screen shot of the code and output are also attached.If find any difficulty, feel free to ask in comment section. Please do upvote the answer.Thank you.

Working of the program

• Random class is imported to generate random numbers
• A double array of size 1000 is declared
• fillArray() method is called to fill array with random numbers
• In fillArray() method, a for loop is used to iterate through the array
• nextDouble() method of Random class is used to generate a random number between 0 and 1
• generated random numbers are stored into array.
• In main() method computeStatistics() method is called to perform various calculation and display its result.
• In computeStatistics() method, min,max variables are initialized with first element of the array
• An enhanced for loop is used to iterate through the array
• inside the loop, each element's value is added to variable total.
• Element is compared with max and min values.
• If the element is greater than max,then set it as the new max
• If the element is lesser than min,then set it as the new min
• Mean is calculated by total divided by number of elements
• Results are displayed

Source code

//importing Random class to generate random numbers
import java.util.Random;
public class Main {
    public static void main(String[] args) {
        //declaring an array of 1000 doubles
        double doubles[] = new double[1000];
        //calling fillArray() method to fill array with random values
        double doublesFilled[] = fillArray(doubles);
        //calling computeStatistics() 
        computeStatistics(doublesFilled);
    }

    public static double[] fillArray(double d[]) {
        //creating instance of Random class
        Random rand = new Random();
        //iterate through array
        for (int i = 0; i < 1000; i++) {
            //generating random double value in between 0 and 1
            double randomValue = rand.nextDouble();
            //storing the random value into array
            d[i] = randomValue;
        }
        return d;
    }

    public static void computeStatistics(double arr[]) {
        //declaring variables
        double min, max, total = 0, mean;
        //setting min and max to arr[0]
        min = max = arr[0];
        //iterate each double value in the array using enhanced for loop
        for (double i : arr) {
            //finding total
            total = total + i;
            //checking the element is greater than max,if yes set element as new max
            if (i > max)
                max = i;
            //checking the element is smaller than min,if yes set element as new min
            if (i < min)
                min = i;
        }
        //calculating mean
        mean = total / 1000;
        //printing results
        System.out.println("Total value: " + total);
        System.out.println("Mean of the elements: " + mean);
        System.out.println("Minimum of elements: " + min);
        System.out.println("Maximum of elements: " + max);
    }
}

Screen shot of the code

Screen shot of the output