HelloWeb.java

package org.example;

import com.sun.net.httpserver.HttpServer;

import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

public class HelloWeb {

    public static void main(String[] args) throws Exception {
        HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);
        server.setExecutor(Executors.newCachedThreadPool());
        server.start();

        server.createContext("/", httpExchange -> {
            httpExchange.sendResponseHeaders(200, 0);

            try (OutputStream out = httpExchange.getResponseBody()) {
                out.write("Hello World".getBytes());
            }
        });
    }
}

A small http server that returns Hello World ;-)