What’s New in Java 18? Explore the Latest JEP Features and Code Snippets

Hello, I’m DD! Java 18 has been officially released.

Although Java 18 is not a long‑term‑support (LTS) release, the community should still focus on Java 17, which remains the LTS baseline for frameworks such as Spring Boot 3.0.

New Features

Even though Java 18 is a non‑LTS version, it introduces several useful enhancements.

JEP 400

Sets UTF‑8 as the default charset for the standard Java API, ensuring consistent behavior across platforms, locales, and configurations.

JEP 408

Provides a native Web server for simple prototyping, testing, and educational purposes. It is not a replacement for Jetty, Tomcat, or similar servers and is not recommended for production use.

JEP 413

Introduces the @snippet tag for embedding code snippets directly in Javadoc comments.

/**
 * The following code shows how to use {@code Optional.isPresent}:
 * {@snippet:
 * if (v.isPresent()) {
 *     System.out.println("v: " + v.get());
 * }
 * }
 */

External snippets can also be referenced:

/**
 * {@snippet file="ShowOptional.java" region="example"}
 */

public class ShowOptional {
    void show(Optional<String> v) {
        // @start region="example"
        if (v.isPresent()) {
            System.out.println("v: " + v.get());
        }
        // @end
    }
}

JEP 417

Adds an API for vector computations that can be compiled at runtime into the best‑available CPU vector instructions, delivering performance superior to equivalent scalar code.

JEP 418

Defines a Service Provider Interface (SPI) for hostname and address resolution, allowing java.net.InetAddress to use custom resolvers beyond the platform default.

JEP 419

Implements the Foreign Function & Memory API, a key component of Project Panama, simplifying calls from Java to native libraries and replacing the cumbersome Java Native Interface (JNI).

JEP 420

Introduces pattern matching for switch statements, building on the previewed feature from Java 17 and the type‑pattern enhancements from Java 16.

// Old code
if (o instanceof String) {
    String s = (String) o;
    // use s
}

// New code with pattern matching
if (o instanceof String s) {
    // use s
}

Combined with the new switch expression, the code can be further simplified:

static String formatter(Object o) {
    return switch (o) {
        case Integer i -> String.format("int %d", i);
        case Long l    -> String.format("long %d", l);
        case Double d  -> String.format("double %f", d);
        case String s  -> String.format("String %s", s);
        default        -> o.toString();
    };
}

JEP 421

Marks the finalize method on Object as deprecated; it will be removed in future releases in favor of try‑with‑resources and java.lang.ref.Cleaner introduced in Java 9.