This is an example from the book 'Java Game Development with LibGDX' by Lee Stemkoski.

https://www.apress.com/us/book/9781484233238

It's been rewritten in kotlin and uses some libktx shortcuts to chain together Actions into sequnces. The Action that progressively fills a dialog box with text is a handy reusable class.

This works fine on mobile now, but it was originally designed for desktop only, and was actually written in BlueJay.