GET /items

Hub › Java › Beginner › GET /items

Goal

Ship the tier exit artifact: a Spring Boot app with GET /items that returns three items as JSON. After this page you will have a buildable, runnable Maven project that answers a curl from a second terminal.

Prerequisites

• Returning JSON from a record list

What "done" looks like

A reader on another machine clones the project, runs one command, and curl http://localhost:8080/items returns three items as JSON. That is the bar.

We will:

1. Rename HelloController to ItemController and change the path to /items.
2. Move the Item record into its own file so the controller is small.
3. Run the build, then run the app, then curl it.

Code

Delete src/main/java/com/example/itemsapi/HelloController.java.

Create src/main/java/com/example/itemsapi/Item.java:

package com.example.itemsapi;

public record Item(int id, String name) {}

Create src/main/java/com/example/itemsapi/ItemController.java:

package com.example.itemsapi;

import java.util.List;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ItemController {

    @GetMapping("/items")
    public List<Item> items() {
        return List.of(
            new Item(1, "notebook"),
            new Item(2, "pen"),
            new Item(3, "stapler")
        );
    }
}

Leave ItemsApiApplication.java and pom.xml exactly as Spring Initializr generated them.

Build

From the project root:

./mvnw clean package

Maven downloads dependencies on first run, then compiles, runs the generated test, and packages the app into target/items-api-0.0.1-SNAPSHOT.jar. Expected tail:

[INFO] BUILD SUCCESS

Run

Two ways. Either works.

The Maven plugin:

./mvnw spring-boot:run

Or the packaged jar:

java -jar target/items-api-0.0.1-SNAPSHOT.jar

Either prints the Spring banner and ends with:

Tomcat started on port 8080
Started ItemsApiApplication in 1.234 seconds

Verify

In a second terminal:

curl http://localhost:8080/items

Output:

[{"id":1,"name":"notebook"},{"id":2,"name":"pen"},{"id":3,"name":"stapler"}]

With headers:

curl -i http://localhost:8080/items

HTTP/1.1 200
Content-Type: application/json
...

[{"id":1,"name":"notebook"},{"id":2,"name":"pen"},{"id":3,"name":"stapler"}]

Stop the server with Ctrl-C. That is the exit artifact.

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You finished a beginner tier. What's next?

Two paths from here.

1. Go deeper on the same platform. The intermediate tier on this same site teaches you to ship a thing that persists, tests itself, and talks to the world. If you liked beginner, that's the natural next step.
2. Pick up an adjacent platform. The table below routes you across platforms based on what you actually want to build.

You just finished	Natural next platform	Why
iOS beginner	iOS intermediate, then Android beginner	Stay native, then learn the other mobile platform with a head start on the Compose/SwiftUI mental model.
Android beginner	Android intermediate, then Golang beginner	Backend-for-frontend pairs naturally with a mobile client.
Golang beginner	AWS beginner, then Golang intermediate	Deploy your endpoint before adding persistence/tests.
Java beginner	Java intermediate, then AWS beginner	JVM persistence + validation first, then deploy.
AWS beginner	Golang beginner	Have a backend to deploy. AWS without a service to host is reference, not curriculum.

Or jump back to the Hub and pick a different goal.