## Dependency Injection

In the previous step you created a basic RESTful Java application with Quarkus. In this step we'll add a custom bean that will use the _ArC_ extension which provides a CDI-based dependency injection https://quarkus.io/guides/cdi-reference.html[solution] tailored for the Quarkus architecture.

## Add Custom Bean

Let’s modify the application and add a companion bean. In CodeReady, right-click on the `org.acme.people.service` package in the project browser and select _New_ --> _Java Class_. Name the class `GreetingService`, and then copy the below code into the class:

[source,java,role="copypaste"]
----
package org.acme.people.service;

import javax.enterprise.context.ApplicationScoped;

@ApplicationScoped
public class GreetingService {

    private String hostname = System.getenv().getOrDefault("HOSTNAME", "unknown");

    public String greeting(String name) {
        return "hello " + name + " from " + hostname;
    }

}
----

This is an injectable bean that implements a `greeting()` method returning a string `hello <hostname>` (where `<hostname>` is the Linux hostname of the machine on which the code runs).

Next, open the existing `GreetingResource.java` class file and add a new field and method above the existing `hello` method:

[source,java,role="copypaste"]
----
    @Inject
    GreetingService service;

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    @Path("/greeting/{name}")
    public String greeting(@PathParam("name") String name) {
        return service.greeting(name);
    }
----

This will cause our new `GreetingResource` class to be instantiated and injected as the `service` field, and then the method `greeting` accesses this service to return the name.

You may notice that you get red error squigglies when you paste this code due to missing import statements. There are two ways with Che to fix this. Either right-click on the offending statement, and choose **Quick Fix** and then choose to import the missing API, or use the _Assistant_ > _Organize Imports_ menu option to do them en masse. You may need to choose from multiple matches, e.g. make sure you choose to import `javax.ws.rs.PathParam` when fixing the missing `PathParam` import. In general, look for `javax` or other well-known names to import. If you get it wrong you'll find out soon enough.

## Inspect the results

Since we still have our app running frmo before, when you make these changes and reload the endpoint, Quarkus will notice all of these changes and live reload them.

Check that it works as expected by loading the new endpoint using the Preview URL and adding the `/hello/greeting/quarkus` to the end of the URL:

image::images/greetingpage.png[]

Note we are exercising our new bean using the `/hello/greeting` endpoint, and you should see `hello quarkus from <hostname>`.

[NOTE]
====
In this case, the hostname is the hostname from the node the app is running on within Kubernetes and will change later on.
====

## Congratulations!

It's a familiar CDI-based environment for you Enterprise Java developers out there, with powerful mechanisms to reload your code _as you type_ (or very close to realtime). In the next step, we'll create some tests for our app, which should also be familiar to _all_ developers.