数组与List相互转换

  public List<Integer> arrayToList(int[] nums) {
    return Arrays.stream(nums).boxed().collect(Collectors.toList());
  }

  public int[] listToArray(List<Integer> list) {
    return list.stream().mapToInt(Integer::intValue).toArray();
  }

  public List<Integer> arrayToList(Integer[] nums) {
    return new ArrayList<>(Arrays.asList(nums));
  }

  public List<Integer> arrayToList2(Integer[] nums) {
    List<Integer> list = new ArrayList<>();
    Collections.addAll(list, nums);
    return list;
  }

  public List<Integer> arrayToList3(Integer[] nums) {
    return Arrays.stream(nums).collect(Collectors.toList());
  }

  public Integer[] listToArrayBoxed(List<Integer> list) {
    return list.toArray(new Integer[0]);
  }

数组与Set相互转换

  public Set<Integer> arrayToSet(int[] nums) {
    return Arrays.stream(nums).boxed().collect(Collectors.toSet());
  }

  public int[] setToArray(Set<Integer> set) {
    return set.stream().mapToInt(Integer::intValue).toArray();
  }

  public Set<Integer> arrayToSet(Integer[] nums) {
    return new HashSet<>(Arrays.asList(nums));
  }

  public Set<Integer> arrayToSet2(Integer[] nums) {
    Set<Integer> set = new HashSet<>();
    Collections.addAll(set, nums);
    return set;
  }

  public Set<Integer> arrayToSet3(Integer[] nums) {
    return Arrays.stream(nums).collect(Collectors.toSet());
  }

  public Integer[] setToArrayBoxed(Set<Integer> set) {
    return set.toArray(new Integer[0]);
  }