CODEWITHSUNDEEP
dartflutter
jsdaniell
jsdaniell

Reputation: 410

How to access and edit a value of a existent key of a map that's inside a list on Dart/Flutter?

I'm create a list of maps, each map have two keys ["title"] and ["time"], all the values of keys is submitted in a setState method, with the values submited as Strings by a button, and a map object is added inside the list, that's List _tasks = [], so what I would like to do is access the ["time"] element of the last Map added in the list and be able to change the value.

This is part of a little project of application, to help me to learn more about Flutter. The repository of application is on Github on https://github.com/jsdaniell/remindme

The list is declared:

List _tasks = [];

The function that's adding a map object to the list:

void _addTask() {
    setState(
      () {
        Map<String, dynamic> newTask = Map();
        newTask["title"] = _taskController.text;
        newTask["time"] = _timeGlobal.toString();
        _taskController.text = "";
        _tasks.add(newTask);


      },
    );

  }

The point is that I want to subtract a value of 1 every second of variable _timeGlobal, what's a int in the global scope and is the value that is set as a String in the ["time"] in the Map, so I write this code:

  String countdownTime(Map newTask) {

    Timer timer = new Timer.periodic(new Duration(seconds: 1), (timer) {

        // Here I want to access the value of ["time"] element, where's in the last position of list and update the value.

        _saveData();

        return Home();

    });

    // Stop the periodic timer using another timer which runs only once after specified duration

    new Timer(new Duration(minutes: _timeGlobal), () {
      timer.cancel();
    });
  }

I hope that have some way to access the last map in a list of maps, and a specific key on this map.

Upvotes: 1

Views: 2364

Answers (1)

abdalmonem
abdalmonem

Reputation: 1422

to access to the last element in the list you can use : _tasks[_tasks.length - 1]; so if you want the "time" key from the Map thats inside the last element of your list use : var lastTime = _tasks[_tasks.length - 1]["time"];

Upvotes: 1

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