CODEWITHSUNDEEP
flutterdart
Lalit Rawat
Lalit Rawat

Reputation: 1272

how to create mutliple objects of a single list

i want to create 4 new lists from a single list. i created this, in this if i do some changes in a single list it changed to all of them. i want to manipulate each list individually.

  List<DietModel> foodList = [];
  List<DietModel> breakFastList = [];
  List<DietModel> lunchList = [];
  List<DietModel> snacksList = [];
  List<DietModel> dinnerList = [];

 void getFoodList() async {
    foodList = await _dietPageRepositoryImpl.getAll();
    breakFastList =  foodList;
    lunchList = foodList;
    snacksList = foodList;
    dinnerList = foodList;
  }

Upvotes: 1

Views: 58

Answers (3)

kimeuvade
kimeuvade

Reputation: 199

By using breakFastList = foodList; you set breakFastList to be foodList, meaning that if foodList changes, breakFastList will also change.

By using breakFastList.addAll(foodList); you will add each item that exists in foodList to breakFastList individually. Meaning that if you delete an item from foodList, or add an item to foodList afterwards, breakFastList will remain the same.

Upvotes: 1

Maz341
Maz341

Reputation: 2439

First you have to initialize your list like you did

List<DietModel> foodList;
List<DietModel> breakFastList;
List<DietModel> lunchList;
List<DietModel> snacksList ;
List<DietModel> dinnerList;

and then on the flutter initState you have to tell that they are a type of list.

@override
  void initState() {
    super.initState();

    foodList = List();
    breakFastList = List();
    lunchList = List();
    snacksList = List();
    dinnerList = List();
  }

and in the end when you fetch your data you can copy your list data to other 4 lists with this.

void getFoodList() async {
    foodList = await _dietPageRepositoryImpl.getAll();

    breakFastList = List.from(foodList);
    lunchList = List.from(foodList);
    snacksList = List.from(foodList);
    dinnerList = List.from(foodList);
  }

Upvotes: 1

w461
w461

Reputation: 2678

Use List.from(mynewlist) instead of mylist = mynewlist

If anyone knows a workaround for classes - that would be interesting!

Upvotes: 1

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