How to Fix the MaterialStateProperty Error in Flutter Widgets

Learn how to resolve the Flutter error: "The argument type 'MaterialStateProperty RoundedRectangleBorder ' can't be assigned to the parameter type 'OutlinedBorder." This guide will walk you through the solution step-by-step.
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How to Fix the MaterialStateProperty Error in Flutter Widgets

When developing applications in Flutter, you may encounter various errors during the coding process. One common issue arises when attempting to customize a button’s border radius, resulting in the following error message:

"The argument type 'MaterialStateProperty RoundedRectangleBorder ' can't be assigned to the parameter type 'OutlinedBorder."

If you've run into this error, you're not alone! In this guide, we'll explore the root of the problem and provide a clear step-by-step solution.

Understanding the Problem

Here's a snippet of the code that typically generates this error:

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

Identifying the Key Issue

The problem arises because MaterialStateProperty is not necessary for the shape parameter here. The shape parameter requires an OutlinedBorder type directly, rather than a MaterialStateProperty. This mismatch is what triggers the compilation error.

The Solution

Updated Code

Here’s the corrected version of the original code:

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

Key Changes Explained

Choosing an Appropriate Border Radius: In this example, I've used a border radius of 30.0, but feel free to adjust this value to match the design you are aiming for.

Conclusion

Resolving errors in Flutter can feel like a challenge, but understanding the type requirements of specific properties helps immensely. When you encounter the message indicating a mismatch in argument types, remember to check the widget's property type expectations.

With the above changes, your button should display without any issues, showcasing your desired customization in style. Happy coding in Flutter, and may your user interfaces shine with smooth, beautiful buttons!