how to find distinct elements in an array code example

Example 1: javascript get distinct values from array

const categories = ['General', 'Exotic', 'Extreme', 'Extreme', 'General' ,'Water', 'Extreme']
.filter((value, index, categoryArray) => categoryArray.indexOf(value) === index);

This will return an array that has the unique category names
['General', 'Exotic', 'Extreme', 'Water']

Example 2: unique numbers in array java

import java.util.ArrayList;

public class UniqueNumbersInArray {

    public static void main(String[] args) {


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

        ArrayList<Integer> uniqueArr = new ArrayList<Integer>();
        for (int i = 0; i < arr.length; i++) {

            int k = 0;
            if (!uniqueArr.contains(arr[i])){
                uniqueArr.add(arr[i]);
                k++;

                for (int j = i; j < args.length ; j++) {
                    if (arr[i]==arr[j]){
                        k++;
                    }
                }

                System.out.println(arr[i]);
                System.out.println(k);
            }

        }
    }
}