What's New in Java 18
- schick09
- Jul 28
- 3 min read
Java 18, officially released in March 2022, continues the platform’s tradition of steady evolution with a mix of finalized features, preview capabilities, and under-the-hood enhancements.
While not a Long-Term Support (LTS) release, Java 18 offers developers a look at future-facing tools and APIs, particularly in the realm of UTF-8 handling, pattern matching, and simple web services.
Whether you're maintaining enterprise apps or tinkering with side projects, understanding Java 18’s updates can help you write cleaner, faster, and more robust code. Let’s dive into what’s new.
1. UTF-8 by Default (JEP 400)
Java 18 has standardized UTF-8 as the default charset across all platforms. Previously, the default charset was platform-dependent—leading to inconsistent behavior across environments.
Why it matters:
Guarantees consistent encoding for file I/O, network operations, and string handling.
Reduces bugs caused by unexpected character encodings.
Makes Java more predictable across Windows, Linux, and macOS.
For example, Files.writeString(Path.of("output.txt"),"Cafe"); will now always write in UTF-8. Prior to version 18, this was platform-dependent.
2. Simple Web Server (JEP 408)
Java 18 introduces a minimal HTTP web server for testing, prototyping, and educational purposes. It's ideal for serving static content with zero configuration.
Key Features:
Command-line usage: jwebserver
Supports HTTP/1.1, static files, directory browsing
No dependencies or frameworks required
For example, to start a simple web server from BASH:
jwebserver --port 8080 --directory .
Example code to use this new web server:
HttpServer server = SimpleFileServer.createFileServer(
new InetSocketAddress(8000),
Path.of("."), // root directory
);
server.start();
3. Code Snippets in Java API Documentation (JEP 413)
This enhancement lets developers embed actual code snippets in Javadoc comments using the @snippet tag. Unlike traditional code blocks, these are verified at compile-time for correctness.
Benefits:
Snippets are syntax-checked and can be tested
Promotes accuracy and up-to-date documentation
For example:
/**
* Returns the square of a number.
* {@snippet :
* int result = MathUtils.square(5); // 25
* }
*/
public static int square(int x) {
return x * x;
}
4. Pattern Matching for Switch (JEP 420)
This is a second preview for this feature.
Pattern Matching continues its journey through the preview process, now with enhanced support for switch expressions. This makes type-checking and conditional logic far more expressive and safe.
For example:
static String handle(Object obj) {
return switch (obj) {
case Integer i -> "Integer: " + i;
case String s -> "String: " + s;
case null -> "Null value";
default -> "Unknown type";
};
}
New in Preview 2:
Exhaustiveness checking
Guarded patterns
More reliable compiler diagnostics
5. Vector API – Third Incubator (JEP 417)
Java 18 continues the incubation of the Vector API, enabling data-parallel computations that are both safe and high-performance on modern CPUs.
Use Case:High-speed operations on large datasets in scientific computing, machine learning, and game development.
For Example:
var a = FloatVector.fromArray(SPECIES, array1, 0);
var b = FloatVector.fromArray(SPECIES, array2, 0);
var c = a.add(b);
c.intoArray(result, 0);
6. Internet-Address Resolution SPI (JEP 418)
Java 18 introduces a Service Provider Interface (SPI) for DNS lookups. You can now plug in custom DNS resolvers, such as those for testing, enterprise security policies, or hybrid networks.
Why it matters:
Replaces the JVM’s hardwired reliance on platform-native DNS resolution
Easier testing and simulation of network behavior
7. Deprecations and Removals
There are no major removals in Java 18, but as always, deprecated APIs and incubating features are subject to change. Always consult the JDK 18 Migration Guide before upgrading.
Final Thoughts
Java 18 may not be an LTS release, but it continues to move the platform forward in important ways: more predictable behavior (UTF-8), simpler tools (web server), and evolving language features (pattern matching, Vector API). Developers who keep up with these incremental changes will find themselves well-positioned when the next LTS—Java 21—arrives.
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