Remove redundant elements in a sorted array

[Duy Dinh]

 /**
 * Extract unique elements from an array
 * 
 * @param arr input array with redundant elements
 */
public static void removeRedundantElements(ArrayList arr) {
    Collections.sort(arr);
    // remove the same elements
    for (int k = 0; k < arr.size() - 1; k++) {
        Object e = arr.get(k);

        // try to skip same element
        int j = k + 1;
        while (j < arr.size()) {
            if (arr.get(j).equals(e)) {
                arr.remove(j);
                j--;
            }
            j++;
        }
    }
}

[Duy Dinh]

A better way to get unique elements from an array

// temporary array of the same size
    int[] b = new int[a.size()];
    Collections.sort(a);

    // store the first element
    b[0] = a.get(0);
    int bIndex = 1;
    // browse 'a' and collect unique elements into b
    // the element collected must not equal to the previous element
    for (int aIndex = 1; aIndex < a.size(); aIndex++) {
        if (b[bIndex - 1] != a.get(aIndex)) {
            b[bIndex] = a.get(aIndex);
            bIndex++;
        }
    }

    // copy elements in temporary elements from index 0 to bIndex 
    int[] result = Arrays.copyOfRange(b, 0, bIndex);

    return result;