setState() called after dispose()

Cover Image for setState() called after dispose()
Matheus Mello
Matheus Mello
published a few days ago. updated a few hours ago

🕒 How to Fix the "setState() called after dispose()" Error in Flutter

Have you ever encountered the error "setState() called after dispose()" in your Flutter project? It can be quite frustrating, especially when you're not sure why it's happening. In this blog post, we'll explore common issues that can cause this error and provide easy solutions to fix it. Let's dive in! 💪

The Problem: setState() called after dispose()

When you see the error message "setState() called after dispose()", it generally means that you're trying to update the state of a widget that has been disposed of. Disposing of a widget typically happens when it's removed from the widget tree, such as when you navigate away from a screen or close a dialog.

In your case, the error occurs when you wait for 5 seconds and then confirm the selected time in the TimePicker. But why does Flutter try to update the state when you're not actively interacting with the widget? Let's find out! 🤔

The Example Code

Let's take a look at the example code provided to understand the context better:

class DateTimeButton extends State<DateTimeButtonWidget> {
  DateTime selectedDate = new DateTime.now();

  Future initTimePicker() async {
    final TimeOfDay picked = await showTimePicker(
      context: context,
      initialTime: new TimeOfDay(hour: selectedDate.hour, minute: selectedDate.minute),
    );

    if (picked != null) {
      setState(() {
        selectedDate = new DateTime(selectedDate.year, selectedDate.month, selectedDate.day, picked.hour, picked.minute);
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return new RaisedButton(
      child: new Text("${selectedDate.hour} ${selectedDate.minute}"),
      onPressed: () {
        initTimePicker();
      }
    );
  }
}

This code defines a DateTimeButton widget that displays the selected time and opens a TimePicker when pressed. The selected time is stored in the selectedDate variable, and calling setState() updates the widget's state.

The Possible Cause: Widgets with TickerProviderStateMixin

In your project, you mentioned that the issue seems to be related to the usage of TabBar and TabBarView, specifically with the mixin with TickerProviderStateMixin. This mixin is required for animations and provides a ticker that triggers widgets to rebuild when needed.

The continuous refreshing and random state updates you observe might be due to the TabBar and TabBarView widgets constantly triggering state changes. However, let's explore possible solutions to mitigate this issue! 🛠️

The Solutions

To solve the "setState() called after dispose()" error, you can try one or more of the following solutions:

1. Cancel Timer Before Disposing

In your initTimePicker() method, make sure to cancel any active timers before disposing of the widget. This ensures that setState() is not called after the widget has been disposed. Here's an example:

@override
void dispose() {
  _timer?.cancel(); // Cancel any active timers
  super.dispose();
}

2. Use a StatefulWidget for the Parent Widget

If you're using a StatefulWidget for the DateTimeButton widget and experiencing the error, try converting the parent widget of DateTimeButton into a StatefulWidget as well. This can help manage the lifecycle of both widgets together and avoid any potential conflicts.

3. Wrap the Parent Widget with a Builder Widget

Another solution is to wrap the parent widget containing the DateTimeButton with a Builder widget. The Builder widget rebuilds its child whenever its builder callback is called. This ensures that any state changes within the parent widget are handled correctly. Here's an example:

Widget build(BuildContext context) {
  return Builder(
    builder: (BuildContext context) {
      // Your parent widget code here
    },
  );
}

📣 Call-to-Action: Share Your Experience and Solutions

Have you encountered the "setState() called after dispose()" error in your Flutter projects? How did you solve it? Share your experience and solutions in the comments below and help fellow developers overcome this issue!

If you found this blog post helpful, make sure to share it with your friends and colleagues who might be facing similar challenges. Happy coding! 😄🚀


More Stories

Cover Image for How can I echo a newline in a batch file?

How can I echo a newline in a batch file?

updated a few hours ago
batch-filenewlinewindows

🔥 💻 🆒 Title: "Getting a Fresh Start: How to Echo a Newline in a Batch File" Introduction: Hey there, tech enthusiasts! Have you ever found yourself in a sticky situation with your batch file output? We've got your back! In this exciting blog post, we

Matheus Mello
Matheus Mello
Cover Image for How do I run Redis on Windows?

How do I run Redis on Windows?

updated a few hours ago
rediswindows

# Running Redis on Windows: Easy Solutions for Redis Enthusiasts! 🚀 Redis is a powerful and popular in-memory data structure store that offers blazing-fast performance and versatility. However, if you're a Windows user, you might have stumbled upon the c

Matheus Mello
Matheus Mello
Cover Image for Best way to strip punctuation from a string

Best way to strip punctuation from a string

updated a few hours ago
punctuationpythonstring

# The Art of Stripping Punctuation: Simplifying Your Strings 💥✂️ Are you tired of dealing with pesky punctuation marks that cause chaos in your strings? Have no fear, for we have a solution that will strip those buggers away and leave your texts clean an

Matheus Mello
Matheus Mello
Cover Image for Purge or recreate a Ruby on Rails database

Purge or recreate a Ruby on Rails database

updated a few hours ago
rakeruby-on-railsruby-on-rails-3

# Purge or Recreate a Ruby on Rails Database: A Simple Guide 🚀 So, you have a Ruby on Rails database that's full of data, and you're now considering deleting everything and starting from scratch. Should you purge the database or recreate it? 🤔 Well, my

Matheus Mello
Matheus Mello