We will be using a free and open source Java web application development framework called SparkJava for building our REST API.

You need to add the following to the dependencies clause of build.gradle:

implementation 'com.sparkjava:spark-core:2.9.2'

Run a server locally!

Running SparkJava is as easy as follows!

import static spark.Spark.*;
public class ApiServer {
public static void main(String[] args) {
final int PORT_NUM = 7000;
get("/", (req, res) -> "Hello World");

After running the ApiServer, point your browser to http://localhost:7000/ to see the following message!

Hello World!

Notice the following statement

get("/", (req, res) -> "Hello World");

The -> is part of Java's Lambda syntax. This syntax may be strange to you! If that is the case, read the next section (otherwise skip it).