I created a task list. I want to count the tasks length like this:

ongoing tasks = task list length - isDone tasks

I want to find the isDone tasks count in this case. As to the picture isDone tasks = 2.

These are the classes that I created.

class Task {
  final String taskName;
  bool isDone;

  Task({required this.taskName, this.isDone = false});

  void toggleDone() {
    isDone = !isDone;
  }
}

........

class Taskdata with ChangeNotifier {
  final List<Task> _tasks = [];

  UnmodifiableListView<Task> get tasks {
    return UnmodifiableListView(_tasks);
  }

  int get tasksCount {
    return _tasks.length;
  } 
  
}

CodePudding user response：

You can use the where function to filter a list per a certain condition:

 int get tasksCount {
    List<Task> tasksLeft = _tasks.where((task) => !task.isDone)).toList();  //where returns an iterable so we convert it back to a list
    return tasksLeft.length;  
  } 

CodePudding user response：

if something goes wrong, you may need to convert List to Iterable

int get doneCount {
    Iterable<Task> tasksDone = _tasks
        .where((task) => task.isDone)
        .toList(); //where returns an iterable so we convert it back to a list
    return tasksDone.length;
  }