Return only unique ints in an array

import java.io.*;
import java.util.*;

class MyCode {

  /**
   * 1
   * Unique
   *
   * Given an array of integers, return an array with all duplicates removed.*
   *
   * Parameters
   * Input: arr {Array of Integers}
   * Output: {ArrayList of Integers}
   *
   * Constraints
   *
   * Time: O(N)
   * Space: O(N)
   *
   * Examples
   * [1, 2, 4, 4, 5, 6] --> [1, 2, 4, 5, 6]
   * [1, 1, 2, 2, 3, 3]' --> [1, 2, 3]
   * [1, 2, 3, 1, 2] --> [1, 2, 3]
   */

  public static void main (String[] args) {
        int[]arr = new int[]{1, 2, 3, 1, 2};
    //ArrayList<Integer> resultsList = new ArrayList<Integer>();
    //resultsList = unique(arr);
    System.out.println(unique(arr));

    }

   public static ArrayList<Integer> unique(int[] arr) {
      HashSet<Integer> set = new HashSet<Integer>();
      for(int i = 0; i<arr.length; i++){
        set.add(arr[i]);
      }
      ArrayList<Integer> list = new ArrayList<Integer>(set);
      return list;
   }
}