Random Array: Getting min, max, and average

Question

I am writing a class which is supposed to populate an array with random integers. The size of the array is given via user input via the scanner class. You are then supposed to include methods for obtaining the average, minimum, and maximum values, as well as a toString method for displaying the random integers. I have written out the class but cannot get the methods to work in my Driver program. I use array.getMax() and it returns a cannot be applied to given types throw. And my String only ever returns the array address. Can someone please show me where I went wrong?

Class:

import java.util.*;

public class RandomArray {

    public int size;
    private static Random gen = new Random();

    public RandomArray()
    {
        Scanner scan = new Scanner(System.in);

        System.out.print("Enter the size of the array: ");
        size = scan.nextInt();

        int[] array  = new int[size];

        for (int i = 0; i < array.length; i++)

        array[i] = gen.nextInt(50) + 1;
    }

    public int getMax(int[] array)
    {
        int max = 0;
        for (int i = 0; i < array.length; i++)

            if (array[i] > max) {
                max = array[i];
            }

        return max;
    }

    public int getMin(int[] array)
    {
        int min = 52;
        for (int i = 0; i < array.length; i++)



            if (array[i] < min) {
                min = array[i];
            }

        return min;
    }

    public double getAvg(int[] array)
    {
        double total = (double) size;
        double avg, sumOf;

        int sum = 0;


        for (int i : array)
            sum += i;

        sumOf = (double) sum;

        avg = sumOf / total;


        return avg;
    }

    public String toString(int[] array)
    {
        String result = "";

        for (int i = 0; i < array.length; i++)


        result = result + array[i];

        return result;
    }
}

Here is the driver program (I also do not know how to make the average display after I have called it):

import java.util.*;

public class RandomArrayDriver {

    public static void main(String[] args)
    {
        int value;
        RandomArray one = new RandomArray();

        one.getAvg();
        one.getMax();
        one.getMin();

        System.out.print("The contents are: " + one.toString());
    }
}

Please [take the tour](http://stackoverflow.com/tour) to see how the site works and what questions are on topic here, and [edit] your question accordingly. See also: [How to Debug Small Programs](https://ericlippert.com/2014/03/05/how-to-debug-small-programs/) — Joe C, Jan 22 '18 at 22:33
In your code i don't see you making use of written values from the public functions of Scanner class — Maddy, Jan 22 '18 at 22:42
I'd recommend including the output of the exception that is thrown and the stack trace. This will help people identify the source of the problem more quickly. — kunruh, Jan 22 '18 at 22:59

score 0 · Answer 1 · answered Jan 22 '18 at 22:39

Hi if your array is of primitive datatype then you don't have to write custom code to find the max and min values you can make use of array.sort function to sort your array. Once sorted your first index will be the min value and the last index of the array shall have the max value. Something like below:

int[] nums= {1, 4, 2, 5, 8};
Arrays.sort(nums);
System.out.println("Minimum = " + nums[0]);
System.out.println("Maximum = " + nums[nums.length-1]);

score 0 · Accepted Answer · answered Jan 22 '18 at 23:18

Based on the code you posted, it shouldn't run in this state. When I ran it I got different exceptions than you reported, but nonetheless, here's a few pointers to get it running:

Your constructor for RandomArray is initializing array as a local variable and as soon as it is done, that reference is lost. Most likely what you want is to make the array an instance variable instead. Then, your other class methods can access that array when they are doing their calculations.
In your RandomArrayDriver, you are making calls to your class methods on the one instance without passing parameters, but your definitions for those methods in RandomArray specify one int[] argument. If you refactor your code based on the point made above, you should be able to remove these and your driver will run correctly.

Hopefully that is enough to get you started. These changes should get the program running at least and other fixes after that should be obvious formatting of the output (hint: toString will output things a little weird in it's current state).

Random Array: Getting min, max, and average

2 Answers2