Скачать или смотреть Fixing the NoSuchMethodError in Flutter: Handling LatLng Responsively

Learn how to resolve the `NoSuchMethodError` when passing latitude and longitude in Flutter. This post discusses effective strategies for handling async operations in your Flutter apps.
---
This video is based on the question https://stackoverflow.com/q/66614160/ asked by the user 'avish' ( https://stackoverflow.com/u/15388676/ ) and on the answer https://stackoverflow.com/a/66624317/ provided by the user 'glavigno' ( https://stackoverflow.com/u/12107390/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Error when passing latitude and longitude to Latlng in flutter

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Fixing the NoSuchMethodError in Flutter: Handling LatLng Responsively

When developing a Flutter application that involves displaying maps, you might encounter an issue related to passing latitude and longitude values to the LatLng object. This can lead to a frustrating error message indicating that a NoSuchMethodError was thrown because the method compareTo was called on null. If you've faced this issue, you're not alone! In this guide, we’ll dive into the problem and walk you through a reliable solution to make your map display seamlessly.

Understanding the Problem

In Flutter, when building components that depend on asynchronous data, you often run into timing issues. In this case, when the showMap widget is being called, it's possible that the values for latitude and longitude have not yet been retrieved. This results in passing null values to LatLng, causing the app to throw an error.

Here’s a closer look at the relevant code where this issue arises:

[[See Video to Reveal this Text or Code Snippet]]

As you can see, if latitude or longitude is null, it results in the error:

[[See Video to Reveal this Text or Code Snippet]]

A Solution: Displaying a Loader While Fetching Location

The key to solving this issue is ensuring that the location data is available before it’s used. Here’s how you can achieve that step-by-step:

Step 1: Introduce State Variables

First, you’ll want to create state variables to manage the loading state and the coordinates. Modify your _HomePageState class as follows:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update the Build Method

Now that we have a loading state, update the build method to either display a loader or the map based on isLoading:

[[See Video to Reveal this Text or Code Snippet]]

Summary of Changes

Loading State: Introduced isLoading as a state variable to manage the loading status.

Set State in Async Method: Called setState to update the widget when location data is fetched.

Conditional Rendering: Used a conditional statement to display either a loading indicator or the map based on whether the data has been loaded.

Conclusion

By implementing a simple loading state, you can effectively manage the asynchronous operations in your Flutter app. This not only prevents runtime errors but also enhances the user experience by providing feedback during data fetching. Next time you’re working with location data, remember to handle your asynchronous calls responsibly. Happy coding!