Скачать или смотреть How to Create a Static Class Derived from MonoBehaviour in Unity

Discover how to implement a static class derived from MonoBehaviour in Unity, solve common issues like Null Reference Exceptions, and streamline your game development.
---
This video is based on the question https://stackoverflow.com/q/64328697/ asked by the user 'I-am-developer-9' ( https://stackoverflow.com/u/14412408/ ) and on the answer https://stackoverflow.com/a/64330196/ provided by the user 'D.B' ( https://stackoverflow.com/u/6224598/ ) 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: How to make a static class Derive by MonoBehaviour

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.
---
Creating a Static Class Derived from MonoBehaviour in Unity

As a game developer using Unity, you'll often run into issues when trying to manage your classes and data efficiently. One common challenge is accessing variables across different classes, especially when you're trying to implement a singleton pattern. If you've come across the error message "Null Reference Exception: Object reference not set to an instance of an object," you're not alone. Let’s explore how to solve this problem by creating a static class derived from MonoBehaviour in Unity.

Understanding the Problem

In your case, you have a script that manages certain player preferences, such as width, height, and position coordinates for a bullet in your game. The goal is to access this data from other classes, which is typically done using the singleton design pattern. Here’s a breakdown of the original script you provided:

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

When you tried to access the width variable from another class through SizePositionForBullet.Instance.width, you encountered a Null Reference Exception. This issue arises when the instance (_instance) you are trying to access has not been initialized.

Solution Walkthrough

Step 1: Make the Instance Static

First and foremost, one common mistake is to forget to make your _instance variable static. Here’s how you would correct it to ensure it works properly:

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

By making _instance static, you ensure that there's only one instance of SizePositionForBullet that can be referenced throughout your game.

Step 2: Remove Unnecessary Inclusion of MonoBehaviour

If your class is solely responsible for managing player preferences using PlayerPrefs, you might not need to derive from MonoBehaviour. Instead, consider creating a simpler player settings class, like this:

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

This class now manages its own instance and can be accessed without worrying about Unity's object lifecycle, thus leading to fewer complications.

Step 3: Accessing the Instance

Once you have refactored your class, accessing the instance is straightforward:

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

This access method is clean, straightforward, and prevents the Null Reference Exception you faced earlier.

Conclusion

Designing classes in Unity that efficiently handle player preferences and data can be streamlined by understanding the nuances of singletons and their implementation. By ensuring that your instances are static and considering whether you need to derive from MonoBehaviour, you can significantly reduce the risk of encountering common pitfalls. Always keep your structure simple, and you'll find that managing state and behavior in your game becomes a lot easier.

Implement these changes, and your game development process will be more robust and error-free. Happy coding!