Finding the difference of two arrays.

Here’s a Java program that finds the difference between two arrays:

import java.util.ArrayList;

 import java.util.Arrays;

 import java.util.List;

 public class ArrayDifference {

    public static void main(String[] args) {

        int[] array1 = {1, 2, 3, 4, 5};

        int[] array2 = {4, 5, 6, 7, 8};

        int[] difference = findDifference(array1, array2);

        System.out.println("Array Difference: " + Arrays.toString(difference));

    }

    public static int[] findDifference(int[] array1, int[] array2) {

        List<Integer> differenceList = new ArrayList<>();

        for (int num : array1) {

            if (!contains(array2, num)) {

                differenceList.add(num);

            }
        }

        int[] differenceArray = new int[differenceList.size()];

        for (int i = 0; i < differenceList.size(); i++) {

            differenceArray[i] = differenceList.get(i);

        }
        return differenceArray;

    }

    public static boolean contains(int[] array, int num) {

        for (int i : array) {

            if (i == num) {

                return true;
          }

        }

        return false;
    }

}

In this program, we have the `findDifference` method that takes two arrays as input and returns an array containing the elements that are present in the first array but not in the second array. The `contains` method is a helper method that checks whether a given number is present in the array.

In the `main` method, we have two example arrays `array1` and `array2`. We call the `findDifference` method with these arrays and store the result in the `difference` array. Finally, we print the `difference` array to display the elements that are different between the two arrays.

Running this program will give you the output:

Array Difference: [1, 2, 3]

Here, the elements 1, 2, and 3 are present in `array1` but not in `array2`, so they are considered as the difference.