import java.util.Arrays;

public class Duplicates {
  public static <T> T[] removeDups(T[] xs) {
    T[] ys = Arrays.copyOf(xs, xs.length);  // create a copy for sorting, leaving xs untouched
    T[] zs = Arrays.copyOf(xs, xs.length);  // result array
    Arrays.sort(ys);

    int size = 0;

    for (int i = 1; i < ys.length; i++) {   // compare with predecessor, only add if different
      if (!ys[i-1].equals(ys[i]))
        zs[size++] = ys[i-1];
    }

    zs[size++] = ys[ys.length - 1];         // we can't compare the last element, so add it

    return Arrays.copyOf(zs, size);         // return the array with right size
  }

  public static <T> boolean hasDups(T[] xs) {
    T[] ys = Arrays.copyOf(xs, xs.length);
    Arrays.sort(ys);

    for (int i = 1; i < ys.length; i++)
      if (ys[i-1].equals(ys[i]))
        return true;

    return false;
  }

  public static void main(String[] args) {
    Integer[] xs = {4,4,4,4,3,2,3,2,3,4,2,1,2,2,3,3,3,4,4,4,4};

    Integer[] ys = removeDups(xs);

    System.out.println(Arrays.toString(ys));
    System.out.println(hasDups(xs));
    System.out.println(hasDups(removeDups(xs)));

    // Should be tested more thoroughly, but that is left as an exercise ;-)
  }
}