flutter, dart list 합치기 expand

[[1,2,3], [4,5,6], [7,8,9]] 를 [1,2,3,4,5,6,7,8,9] 로 바꾸어 줌.

 

https://sunnybong.tistory.com/256

[다트] 리스트 합치기

 

void main() {

  var list1 = [1,2,3,4];
  var list2 = [5,6,7,8];
  var list3 = [9,10,11,12];

  // #1 addAll
  var newlist1 = List.from(list1)..addAll(list2);
  print(newlist1);

  // #2 expand
  var newlist2 = [list1, list2].expand((x) => x).toList();
  print(newlist2);
  var newlist2_1 = [list1, list2, list3].expand((x) => x).toList();
  print(newlist2_1);

  // #3 after Dart 2.3 (...)
  var newlist3 = [...list1, ...list2, ...list3];
  print(newlist3);



}

 

 

https://www.educative.io/answers/how-to-combine-lists-using-the-expand-method-in-dart

How to combine lists using the expand() method in Dart