MainView.java

package com.overliambitious.vaadin.frontend;

import com.vaadin.flow.component.button.Button;
import com.vaadin.flow.component.html.Label;
import com.vaadin.flow.component.notification.Notification;
import com.vaadin.flow.component.orderedlayout.VerticalLayout;
import com.vaadin.flow.router.Route;

import javax.annotation.PostConstruct;

@Route("")
public class MainView extends VerticalLayout {

    @PostConstruct
    public void init() {
        Notification notification = new Notification("Hello!", 3000);
        Label label = new Label("Hello World!");
        Button button = new Button("Click here!", click -> notification.open());
        add(notification);
        add(label);
        add(button);
    }
}