Flutter
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Kodebits Day 56: Factory Constructor
Jul 12 2026
Practice factory constructors with a short dart challenge.
What does this print?
class Box {
final int val;
Box._(this.val);
factory Box(int n) =>
Box._(n * 2);
}
void main() {
print(Box(3).val);
}
Try it in the online Dart Playground →
[spoiler title="Solution"]
Answer:
6
Explanation:
The factory constructor Box(int n) processes the input value before passing it to the private constructor Box._().
[/spoiler]