Can you explain what the Vaadin framework is and its main features?

Vaadin is a Java framework for building web applications with rich user interfaces. It allows developers to write UI code in Java, which is then rendered in the browser, often without writing JavaScript.

Main features of Vaadin:

• Server-side UI rendering: all UI logic is written in Java, and Vaadin manages the browser updates.
• Component-based architecture: a wide range of ready-to-use UI components (tables, forms, buttons, etc.).
• Integration with Java ecosystem: easily use Spring, CDI, and other technologies.
• Support for modern web standards: built on Web Components.
• No need to write JavaScript: developers work only with Java.

Example of a simple Vaadin application:

public class MainView extends VerticalLayout {
    public MainView() {
        Button button = new Button("Click me", e -> {
            Notification.show("Hello from Vaadin!");
        });
        add(button);
    }
}