public class ArrayUtil {

/**
 * Field INPUT_LESS_THAN_TWO. (value is 2)
 */
private static final int INPUT_LESS_THAN_TWO = 2;

/**
 * Method removeDuplicateElement. Given a sorted array of integers, this
 * method removes the duplicate elements. Input array is sorted array and
 * can have only negative values, only positive value or a mix of both.
 *
 * @param inputArray
 *            int[]
 *
 * @return int[]
 * @throws IllegalArgumentException
 */
public int[] removeDuplicateElement(final int[] inputArray)
        throws IllegalArgumentException {

    int j = 0; // Marks the begining of the array
    int i = 1; // Points toward the second element in the array

    if (null == inputArray || 0 == inputArray.length) {
        throw new IllegalArgumentException(
                "Input Array is either null or of zero length");
    } // end of null and 0 length check

    // Return if the input array has only one item
    if (inputArray.length < INPUT_LESS_THAN_TWO) {
        return inputArray;
    } // end of check for length less than 2
    while (i < inputArray.length) {
        if (inputArray[i] == inputArray[j]) {
            i++;
        } else {
            inputArray[++j] = inputArray[i++];
        }
    } // end of while loop

    // copy and return the array
    final int[] outputArray = new int[j + 1];
    for (int k = 0; k < outputArray.length; k++) {
        outputArray[k] = inputArray[k];
    }

    return outputArray;
}