how to use setState to update a property of a list element?-CodePudding

I have a list of download tasks as datasource for ListView. After the list is created, I'll start all tasks and when any task is done, I'll update task.isDone property so changes are reflected to UI. How do I do this with setState?:

// My list of tasks used in ListView
List<Task> _tasks;

Future<void> onl oaded() async {
    // Load initial tasks.
    var tasks = await loadTasks();
    // Set state.
    setState(() {
        _tasks = tasks;
    });
    // Start tasks.
    _tasks.map((task) async {
      // When any task is done, update the state and UI.
      await startDownload(task);
      setState(() {
        // Can I do this?
        task.isDone = true;
      });
    });
}

CodePudding user response：

You can start your task when the first setState finished and this means after the ui rebuild, so try this:

Future<void> onl oaded() async {
    // Load initial tasks.
    var tasks = await loadTasks();
    // Set state.
    setState(() {
        _tasks = tasks;
    });

    WidgetsBinding.instance.addPostFrameCallback((_) { // <---- add this
        // Start tasks.
        _tasks.map((task) async {
          // When any task is done, update the state and UI.
          await startDownload(task);
          setState(() {
            task.isDone = true;
          });
        });
    });
}

CodePudding user response：

if setState is not working. try super.setState((){...})