opon new window from different package :D

Hallo. I am newbie in programming in Java and I don’t know how to open window. I have main class “hallo” where I want to have just code and class “mainPanel” in different package where is GUI (buttons text area etc…). I want to run on server class hallo and open panel. Can someone please send me some programme or write me where I can find some usefull information?

Thank you :slight_smile:

Please have a look at
Vaadin Book
& Blogs as a first step to start with Vaadin.

If you are new to Java & JEE Oracle website is good place to start with.

If you already know Java & need facing certain issue with Vaadin, Please share your code.