How to a sort a big list lazily (to escape Stack Overflow)?-CodePudding

I have a big list of 50k lines. Now when I try to sort it with list.sort it throws Stack Overflow error.
How to make the sorting work lazily without filling the stack?

List<List<dynamic>> sortData(List<List<dynamic>> data,
    {int sortItemNumber = 4}) {
  data.sort((List<dynamic> a, List<dynamic> b) {
    return compare(a[sortItemNumber], b[sortItemNumber]);
  });
  return data;
}

int compare(var itemA, var itemB) {
  if (itemA.runtimeType == String || itemB.runtimeType == String) {
    return -1;
  }
  return itemA.compareTo(itemB);
}

CodePudding user response：

Your compare function always returns -1 for certain inputs. Those inputs can't be sorted, because there's no way to know if an element comes before or after anything else - you're saying a<b and b<a are both simultaneously true. So the sort fails. Different sorting algorithms will fail in different ways, yours evidently generates a stack overflow probably due to infinite recursion.

Since you say this is just for testing at the moment, you could try replacing with return 0 to indicate those items are equivalent and thus already in the proper order. The sort will still be incorrect, but it probably won't crash any more.

CodePudding user response：

always ignore whatever mark ransom says , that's my best advice