Quick sort in java

QuickSort.java

import java.util.Arrays;

public class problemSolving {

    static void quickSort(int[] array, int l, int r) {
        //We first check if the left-most element index is greater than right-most element index

        //This is considered as a base case to exit from infinite recursive calls
        if (l >= r) {
            return;
        }
        //We then take the pivot element which may be a random one but we choose the first element for instance
        var pivot = partition(array, l, r);
        //We make two quick sort for left and hand side arrays recursively.
        quickSort(array, l, pivot - 1);
        quickSort(array, pivot + 1, r);

    }

    static int partition(int[] array, int l, int r) {
        //We make the first element of the array or sub-array be the pivot
        var pivot = array[l];
        //We make a counter which helps us to swap between smaller number and bigger number so smaller numbers
        //go to the left of pivot and bigger ones go to the right
        var j = l;
        for (int i = l + 1; i <= r; i++) {
            //If the element is smaller than the pivot, move the cursor 'j' to next element and make a swap.
            if (array[i] <= pivot) {
                j++;
                swap(array, j, i);
            }
        }
        //After you push the smaller elements to the right, then you make a swap to the 'j' element and the pivot
        swap(array, j, l);
        return j;
    }

    static void swap(int[] array, int index1, int index2) {
        int temp = array[index1];
        array[index1] = array[index2];
        array[index2] = temp;
    }


    public static void main(String[] args) {
        int[] array = {6, 4, 2, 1, 4, 6, 7, 8, 30, 4, 3, 2};
        quickSort(array, 0, array.length - 1);
        System.out.println(Arrays.toString(array));
    }
}