algorithm comparison main()

public static void main(String[] args) {
    int[] elements1 = new int[100000];
    Random random = new Random();

    /* Generate random elements */
    for (int i = 0; i < elements1.length; i++) {
        elements1[i] = random.nextInt(1000);
    }

    /* Create "clones" of the original array, for same sorting conditions */
    int[] elements2 = elements1.clone();
    int[] elements3 = elements1.clone();
    int[] elements4 = elements1.clone();

    /* Bubble sort */
    long start = System.currentTimeMillis();
    BubbleSort.sort(elements1);
    System.out.println("bubble sort:\t" + (System.currentTimeMillis() - start) + " ms");

    /* Selection sort */
    start = System.currentTimeMillis();
    SelectionSort.sort(elements2);
    System.out.println("selection sort:\t" + (System.currentTimeMillis() - start) + " ms");

    /* Insertion sort */
    start = System.currentTimeMillis();
    InsertionSort.sort(elements3);
    System.out.println("insertion sort:\t" + (System.currentTimeMillis() - start) + " ms");

    /* Shell sort */
    start = System.currentTimeMillis();
    ShellSort.sort(elements4);
    System.out.println("Shell sort:\t" + (System.currentTimeMillis() - start) + " ms");
}