Find the Difference of Two Arrays LeetCode solution in Java

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class Solution {
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  public List<List<Integer>> findDifference(int[] nums1, int[] nums2) {
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    Set<Integer> set1 = new HashSet<>(); // create 2 hashsets
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    Set<Integer> set2 = new HashSet<>();
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    for (int num : nums1) {
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      set1.add(num);
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    } // add nums1 elements to set1
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    for (int num : nums2) {
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      set2.add(num);
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    } // add nums2 elements to set2
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    List<List<Integer>> resultList =
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        new ArrayList<>(); // Initialize result list with 2 empty sublists that we will return
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    resultList.add(new ArrayList<>());
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    resultList.add(new ArrayList<>());
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    for (int num : set1) { // just iterate to all elements of set1
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      if (!set2.contains(num)) {
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        resultList.get(0).add(num);
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      } // add those elements to first sublist of result list, which are not in set2.
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    }
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    for (int num : set2) { // just iterate to all elements of set2
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      if (!set1.contains(num)) {
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        resultList.get(1).add(num);
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      } // add those elements to first sublist of result list, which are not in set1
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    }
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    return resultList;
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  }
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}