Merge two lists of objects in Dart - list

Question

I have objects which have a parameter name and a parameter counter. Those objects are stores inside a list. Some of the items in my list have the duplicate parameter "name". I want to remove the duplicates inside the list and add the counter of that duplicate to the duplicate-objects parameter.
class Person{
Person({this.name, this.counter)};
String name;
int counter;
}
List<Person> theList = [];
theList.add(Person(name:"Ben", counter: 2);
theList.add(Person(name:"Ben", counter: 5);
//I need a function that changes the List to show Ben with counter 7

Answer 1

class Person{
final String name;
int counter;
Person({required this.name, required this.counter});
}
extension on List<Person> {
void addPerson({required String name, required int counter}) {
if (isNotEmpty) {
try {
var person = firstWhere((p) => p.name == name);
person.counter += counter;
} catch(e) {
add(Person(name:name, counter: counter));
}
} else {
add(Person(name:name, counter: counter));
}
}
}
void main() {
var theList = <Person>[];
theList.addPerson(name:"Lucho", counter: 4);
theList.addPerson(name:"Ben", counter: 2);
theList.addPerson(name:"Ben", counter: 5);
print(theList);
print(theList.length);
print("${theList[1].name} - ${theList[1].counter}");
}
Result:
[Instance of 'Person', Instance of 'Person']
2
Ben - 7

Answer 2

first define a class for a list of Persons:
class PersonList{
List<Person> _personList = [];
get personList{
return [..._personList];
}
void addToList(Person person){
for(int i=0; i<_personList.length; i++){
if(_personList[i].name == person.name){
_personList[i].counter = _personList[i].counter + person.counter;
return;
}
}
_personList.add(person);
return;
}
}
then, you can create a new instance of it and add some entries to the list:
PersonList theList = new PersonList();
theList.addToList(Person(name:"Ben", counter: 2));
print(theList.personList[0].counter);
theList.addToList(Person(name:"Ben", counter: 5));
print(theList.personList[0].counter);
feel free to only use the addToList method.