Compact array in Java

import java.lang.reflect.Array;


public class CompactArray<T> {
    /**
     * Just for demo
     *
     * @param args The command line args
     */
    public static void main(String[] args) {
        Integer[] a1 = { 1, 2, 5, 6, 3, 8 };
        // Show original
        System.out.println(java.util.Arrays.toString(a1));
        // Delete the element '5'
        a1[2] = null;
        a1 = (Integer[]) CompactArray.compact(a1);
        System.out.println(java.util.Arrays.toString(a1));

        Integer[] a2 = { 1, 2, 5, 6, 3, 8 };
        // Remove first three elements
        a2 = (Integer[]) CompactArray.compact(a2, new int[] { 0, 1, 2 });
        System.out.println(java.util.Arrays.toString(a2));
    }

    /**
     * Compact an array, removing elements
     * whose indexes are listed in an
     * array of indexes
     *
     * @param original The array to be compacted
     * @param removals The indexes of the elements to remove
     *
     * @return The compacted array
     */
    public static <T> T[] compact(T[] original, int[] removals) {
        T[] result = (T[]) Array.newInstance(original[0].getClass(),
                original.length - removals.length);

        int ixRemovals = 0;
        int ixResult = 0;

        for (int i = 0; i < original.length; i++) {
            if ((ixRemovals < removals.length) && (i == removals[ixRemovals])) {
                ixRemovals++;
            } else {
                result[ixResult++] = original[i];
            }
        }

        return result;
    }

    /**
     * Compact an array, 'removing' any element that
     * is null
     *
     * @param original The array to be compacted
     *
     * @return The compacted array
     */
    public static <T> T[] compact(T[] original) {
        T[] result = null;
        int ix = 0;

        for (int i = 0; i < original.length; i++) {
            if (original[i] != null) {
                original[ix++] = original[i];
            }
        }

        if (ix != original.length) {
            int i;

            for (i = 0; (i < original.length) && (original[i] == null); i++) {
            }

            if (i == original.length) {
                throw new RuntimeException(
                    "All elements null. Cannot determine element type");
            }

            result = (T[]) Array.newInstance(original[i].getClass(), ix);
            System.arraycopy(original, 0, result, 0, result.length);
        }

        return result;
    }
}