Question 78818 in Flutter Question posted in
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Sort Uint8list or List<int> lists in Flutter

i would like to sort Uint8list or List lists in flutter

Example in js:

[ Uint8Array.from([1, 2, 3]), Uint8Array.from([0, 1, 2]) ].sort() -> [[0, 1, 2], [1, 2, 3]]

Thx

Tags:

2

Answers


  1. 0

    you can use this mehode:

    List<List<int>> sortedList(List<List<int>> listOfList) {
int maxLength = 0;
for (var list in listOfList) {
  list.sort((a, b) => a.compareTo(b));
  if (list.length > maxLength) maxLength = list.length;
}
for (int i = 0; i < maxLength; i++) {
  listOfList.sort((a, b) {
    if(a.length-1<i || b.length-1<i) return 0;
    return (a[i].compareTo(b[i]));
  });
}
return listOfList;
}

    input:

    [[3, 5, 8, 9], [3, 4, 8],[5, 9, 8],[5, 3, 8]]

    output:

    [[3, 4, 8], [3, 5, 8, 9], [3, 5, 8], [5, 8, 9]]

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  2. 0

    I’m presuming you want to sort the List<int>s in a similar way to lexicographical sorting of Strings. That is, list1 should precede list2 if list1[n] < list2[n] for some n and if list1[i] == list2[i] for all i < n. If so, basically write a string comparison function but for ints:

    1. Compare each corresponding element.
    2. If they’re not equal, return that comparison result, otherwise keep iterating.
    3. If you run out of elements, return a comparison result that puts the shorter List first.
    import 'dart:typed_data';

int compareListInts(List<int> list1, List<int> list2) {
  for (var i = 0; i < list1.length && i < list2.length; i += 1) {
    if (list1[i] < list2[i]) {
      return -1;
    } else if (list1[i] > list2[i]) {
      return 1;
    }
  }

  if (list1.length < list2.length) {
    return -1;
  } else if (list1.length > list2.length) {
    return 1;
  }

  return 0;
}

void main() {
  var listOfLists = [
    Uint8List.fromList([1, 2, 3]),
    Uint8List.fromList([0, 1, 2]),
    Uint8List.fromList([2, 3]),
    Uint8List.fromList([0, 1]),
  ];

  listOfLists
    ..sort(compareListInts)
    ..forEach(print);
}

    which prints:

    [0, 1]
[0, 1, 2]
[1, 2, 3]
[2, 3]
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