Meaning of Triple Dots [...] in Flutter Syntax
Dart 2.3 introduced the spread operator (...) and the null-aware spread operator (...?), which provide a concise way to insert multiple elements into a collection.
For example, you can use the spread operator (...) to insert all the elements of a list into another list:
var list = [1, 2, 3];
var list2 = [0, ...list];
assert(list2.length == 4);
If the expression to the right of the spread operator might be null, you can avoid exceptions by using a null-aware spread operator (...?):
var list;
var list2 = [0, ...?list];
assert(list2.length == 1);
For more details and examples of using the spread operator, see the spread operator proposal.
spread operator (...)
is used to provide a way to assign values to Collections, more commonly it found inside the column to render its child.
List<String> values = ['one', 'two', 'three'];
return Scaffold(
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
...values.map((value) {
return Text(value);
}),
],
),
),
);
Output:
I used to have this problem. I solved this problem by adding .toList(); to the List Widget.
Widget _build() {
List<Widget> children = [
Text("first child"),
Text("second child"),
Text("third child"),
].toList();
return Column(
children: <Widget>[
...children,
Text("fourth child"),
],
);
}
Hope it helps