Problems with the visibility of methods

Hi, when I go to create a custom extension to import on App Inventor, the methods I made are not visible in the interface, how can I solve? Following are attached the problem I encounter and the code I created. Thank you and good day,
Di Dio Lorenzo.

You need to annotate methods with @SimpleFunction @SimpleProperty , or @SimpleEvent .

how? I am sorry but I am a beginner.

My aim is to be able to communicate if a string is valid or not, according to a specific pattern.

Since you are still a beginner, you should learn from several tutorials before creating extensions,
see all these tutorials :

Create Extensions - Kodular Docs

Extensions App inventor 2 Create Extensions Tutorial Build extensions tutorial easy.

What you'll need to begin creating extensions

try to find some open source extension or thesource code of app inventor, you will know how to use the annotation.
FYi already have some extensions about regular expression, like here

I am already following a tutorial (the third specifically) but I cannot solve this problem.

please wait im still search cool tutorial that will help you a lot, just wait on this post

Thank you, I followed the video but failed to solve my problem...

take a look at the code in this guide and compare it with yours

This maybe helpful for you