Скачать или смотреть Resolving the Object reference not set to an instance of an object Error in Unity with DateTime

Discover how to fix the `Object reference not set` error in Unity when dealing with DateTime variables. Understand the simple changes needed to prevent a common null reference exception.
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This video is based on the question https://stackoverflow.com/q/71034151/ asked by the user 'thirteen4054' ( https://stackoverflow.com/u/7004196/ ) and on the answer https://stackoverflow.com/a/71034180/ provided by the user 'PaulF' ( https://stackoverflow.com/u/3070060/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the "Object reference not set to an instance of an object" Error in C- (Unity)

If you're a Unity developer, you've probably encountered the frustrating Object reference not set to an instance of an object error. This is a common issue in C- code, particularly when dealing with objects that can potentially be null. In this guide, we'll explore a specific scenario concerning DateTime variables that results in this error and how to resolve it effectively.

The Problem

In our scenario, the code block attempts to call a method on an object that hasn't been instantiated. Here's the relevant snippet of code:

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

The line that leads to the NullReferenceException is dates.SetDailyWeeklyDate(tempDate);. If dates is null, your code tries to call SetDailyWeeklyDate on a non-existent object, resulting in an error.

What Happens in the Code

Check for Null: The initial if(dates == null) statement checks if the object dates is null.

Set Date: It retrieves the current date and time using WorldTimeAPI.instance.GetCurrentDateTime() and prints it.

Error Occurrence: The program attempts to call SetDailyWeeklyDate(tempDate) on dates, which throws the error if dates is indeed null.

The Solution: Fixing the Null Reference Exception

To prevent this error, you have two viable solutions:

1. Change the Conditional Check

Instead of checking if dates is null, you should check if it's not null. This way, the code only tries to set the date if dates has been successfully instantiated:

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

2. Instantiate the Dates Object and Avoid Null

If your logic requires that the dates object should be created if it doesn't exist, you should instantiate it before calling the SetDailyWeeklyDate method. For instance, you can do something like this:

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

Conclusion

The Object reference not set to an instance of an object error occurs due to attempting to access methods or properties on an uninitialized object. In our case involving DateTime, the solution is straightforward: either check for a valid object before executing the method or create a new instance when none exists.

By following these steps, you can effectively prevent this common error and ensure your Unity projects run smoothly. Fixing these issues not only makes your code more robust but also improves the overall quality of your game development experience.