Creating a modern Java application: Part 1

public class App {
    public static void main(String[] args) {
        // Java 16: record classes.
        // https://docs.oracle.com/en/java/javase/16/language/records.html
        // Both `Author` and `Book` are record classes.
        // They are created by a simple one-liner (at the minimum):
        // public record Author(String firstName, String lastName) {}
        // public record Book(String title, Author[] authors) {}

        // Java 10: implicit typing with the `var` keyword
        // https://docs.oracle.com/en/java/javase/17/language/local-variable-type-inference.html
        // No need to do something like:
        // Author john = new Author(...);
        var john = new Author("John", "Doe");
        var jane = new Author("Jane", "Doe");

        var book1 = new Book("My name is John Doe", new Author[]{john});
        var book2 = new Book("My name is Jane Doe", new Author[]{jane});
        var book3 = new Book("We are the Does", new Author[]{john, jane});

        // Java 8: Lambdas and the stream API
        // https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html
        // Similar to JavaScript, Python and other higher-level languages, we can
        // chain together operations on groups of objects.
        var janeBooks = Stream.
                of(book1, book2, book3)
                // Java 11: local variable type inference
                // https://docs.oracle.com/en/java/javase/17/language/local-variable-type-inference.html
                // The variable `book` can be inferred as a `Book` type.
                .filter((var book) -> Arrays.asList(book.authors()).contains(jane))
                .toList();

        // Java 8: stream API with method reference
        // We are using `Book::title` to refer to the `Book.title()` method from the record class
        var bookTitles = janeBooks
                .stream()
                .map(Book::title)
                .toList();

        // Java 15: Text blocks
        // https://docs.oracle.com/en/java/javase/15/text-blocks/index.html
        // Python developers may be familiar with this syntax already and JavaScript close equivalent
        // is the template string backtick (`).
        System.out.printf("""
                Jane has authored the following books:

                %s
                """, String.join("\n", bookTitles));
    }
}

# Same instructions as on the SDKMAN install link above
$ curl -s "https://get.sdkman.io" | bash

$ sdk version

SDKMAN 5.16.0

$ sdk install java 17-open

[...]

Installing: java 17-open
Done installing!

Setting java 17-open as default.

$ java -version
openjdk version "17" 2021-09-14
OpenJDK Runtime Environment (build 17+35-2724)
OpenJDK 64-Bit Server VM (build 17+35-2724, mixed mode, sharing)

# You can install via their install script
$ curl -Ls https://sh.jbang.dev | bash -s - trust add https://repo1.maven.org/maven2/io/quarkus/quarkus-cli/
$ curl -Ls https://sh.jbang.dev | bash -s - app install --fresh --force quarkus@quarkusio

# Or, since we have SDKMAN already installed, SDKMAN
$ sdk install quarkus

$ quarkus

Quarkus CLI version 2.16.1.Final

Create Quarkus projects with Maven, Gradle, or JBang.
Manage extensions and source registries.

Create: quarkus create
Iterate: quarkus dev
Build and test: quarkus build

[...]

# We are specifying Java 17 and using Maven for our build process.
# `demo-todo` is our app name, which will also be the name of the directory. You can also use the format "com.example:app_name" if you also want to specify a group-id.
$ quarkus create app \
 --java=17 \
 --maven \
 demo-todo
-----------

applying codestarts...
📚  java
🔨  maven
📦  quarkus
📝  config-properties
🔧  dockerfiles
🔧  maven-wrapper
🚀  resteasy-reactive-codestart

-----------
[SUCCESS] ✅  quarkus project has been successfully generated in:
--> /java/quarkus/demo-todo
-----------
Navigate into this directory and get started: quarkus dev

$ quarkus dev
# alternatively, you can use the Maven wrapper that's provided
# `./mvnw compile quarkus:dev`

$ quarkus dev
--2023-02-01 10:12:06--  https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.1.0/maven-wrapper-3.1.0.jar
Resolving repo.maven.apache.org (repo.maven.apache.org)... 146.75.92.215
Connecting to repo.maven.apache.org (repo.maven.apache.org)|146.75.92.215|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 58727 (57K) [application/java-archive]
Saving to: ‘/java/quarkus/demo-todo/.mvn/wrapper/maven-wrapper.jar’

/java/quarkus/demo-todo/.mvn/wrapper 100%[====================================================================================================================================>]  57.35K  --.-KB/s    in 0.02s   

2023-02-01 10:12:06 (2.43 MB/s) - ‘/java/quarkus/demo-todo/.mvn/wrapper/maven-wrapper.jar’ saved [58727/58727]

[INFO] Scanning for projects...
[INFO] 
[INFO] -----------------------< com.example:demo-todo >------------------------
[INFO] Building demo-todo 0.0.1
[INFO] --------------------------------[ jar ]---------------------------------

[...]

Listening for transport dt_socket at address: 5005
__  ____  __  _____   ___  __ ____  ______ 
 --/ __ \/ / / / _ | / _ \/ //_/ / / / __/ 
 -/ /_/ / /_/ / __ |/ , _/ ,< / /_/ /\ \   
--\___\_\____/_/ |_/_/|_/_/|_|\____/___/   
2023-02-01 10:35:41,634 INFO  [io.quarkus] (Quarkus Main Thread) demo-todo 0.0.1 on JVM (powered by Quarkus 2.16.1.Final) started in 0.892s. Listening on: http://localhost:8080

2023-02-01 10:35:41,642 INFO  [io.quarkus] (Quarkus Main Thread) Profile dev activated. Live Coding activated.
2023-02-01 10:35:41,642 INFO  [io.quarkus] (Quarkus Main Thread) Installed features: [cdi, resteasy-reactive, smallrye-context-propagation, vertx]

--
Tests paused
Press [r] to resume testing, [o] Toggle test output, [:] for the terminal, [h] for more options>

$ ./mvnw quarkus:list-extensions
[INFO] Scanning for projects...
[INFO] 
[INFO] -----------------------< com.example:demo-todo >------------------------
[INFO] Building demo-todo 0.0.1
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- quarkus-maven-plugin:2.16.1.Final:list-extensions (default-cli) @ demo-todo ---
[INFO] Current Quarkus extensions available: 
[INFO] 
[INFO] ✬ ArtifactId                                         Extension Name
[INFO] ✬ blaze-persistence-integration-quarkus              Blaze-Persistence
[INFO] ✬ camel-quarkus-activemq                             Camel ActiveMQ
[INFO] ✬ camel-quarkus-amqp                                 Camel AMQP
[INFO] ✬ camel-quarkus-arangodb                             Camel ArangoDb
[INFO] ✬ camel-quarkus-as2                                  Camel AS2

[...]

[INFO] ✬ quarkus-webjars-locator                            WebJar Locator
[INFO] ✬ quarkus-websockets                                 WebSockets
[INFO] ✬ quarkus-websockets-client                          WebSockets Client
[INFO]   quarkus-xmlsec                                     Santuario XML Security
[INFO]   quarkus-zeebe                                      Quarkus - Zeebe - Runtime
[INFO]   quarkus-zookeeper                                  Zookeeper
[INFO] ✬ runtime-tools-quarkus-extension                    Kogito Runtime Tools
[INFO] 
[INFO] To get more information, append `-Dformat=full` to your command line.
[INFO] 
[INFO] To list only extensions from specific category, append `-Dcategory="categoryId"` to your command line.
[INFO] 
[INFO] Add an extension to your project by adding the dependency to your pom.xml or use `./mvnw quarkus:add-extension -Dextensions="artifactId"`

$ curl -i http://localhost:8080/hello

HTTP/1.1 200 OK
Content-Type: text/plain;charset=UTF-8
content-length: 28

Hello from RESTEasy Reactive