Put all maps inside one list - arrays

Question

My problem with Flutter is when I'm converting an array to a list, there is every item is a separated list and I want all the items in just one list.
Example output when putting 2 items:
[{title: ITEM1}, {title: ITEM2}]
I want to put like this:
[{title: ITEM1, title: ITEM2}]
I hope you guys understand the problem
void _addPecas() {
if ((_pecasController.text.isEmpty) ||
((_pecasController.text.trimLeft() == ("")))) {
print("Campo Vazio");
} else {
setState(() {
Map<String, dynamic> newPeca = Map();
newPeca["title"] = _pecasController.text.trimLeft();
_pecasController.text = "";
_pecasList.add(newPeca);
print(_pecasList);
});
}
}

Answer 1

if [{title: ITEM1, title: ITEM2}] is what you want to achieve,
The problem here is that you are creating a new Map called newPeca every time your function runs. .
Map<String, dynamic> newPeca = Map();
So by the time you set your values you call _pecasList.add(newPeca); that new map will be appended to your List thus you get [{title: ITEM1}, {title: ITEM2}]
Working with the assumption that you want only one Map in _pecaList, _newPeca should always reference that one Map
Map<String, dynamic> newPeca = _pecaList[0]
then you can add your desired values newPeca["title"] = _pecasController.text.trimLeft();
One more problem you'll run into, you want to have duplicate keys in the Map, which is not possible.
The newer value in the map will overwrite the existing one.
E.g
newPeca[title] = "Item 1"
newPeca[title] = "Item 2"
newPeca[title] will end up being Item 2

Answer 2

As I understood, you are asking for one Map inside List and add values into that Map and finally add it into a List. Here is how you can do it:
Map<String, dynamic> newPeca = Map();
if (_pecasController.text.isEmpty ||
_pecasController.text.trimLeft() == ("")) { // you had too much unwanted brackets here
print("Campo Vazio");
} else {
setState(() {
newPeca["title"] = _pecasController.text.trimLeft(); // you have to have unique key if you want to keep in one Map. See the dart pad example I have provided a link below
_pecasController.text = "";
// _pecasList = [newPeca]; // this is also working without outside .add() but if the list is long, im not recommending this.
print(_pecasList);
});
}
// outside the iteration
_pecasList.add(newPeca);
Edit simple dart example in dartpad
Update:
Make sure this: Map<String, dynamic> newPeca = Map(); outside the iteration. This way you are not creating Map for each and every iteration. You are adding to same map and that map you should add after each iteration to the List or just create empty list assign as a new list in each and every iteration(Btw, not the performant way).
Secondly, when you add to the list inside iteration each and every time map will add to the list.
Finally, Even if you make those right, your map will not take same value as title because the reason is your key of the map entry is title and you cannot have duplicate keys inside map and the list should be outside the iteration.