Java has continually evolved since its inception, with each new version bringing enhancements and features that improve developer productivity and application performance. In this article, I’ll explore ten essential features introduced in Java 9 and subsequent versions that every developer should be familiar with.
The Java Platform Module System (JPMS) is perhaps the most significant addition to Java 9. It addresses long-standing issues with the classpath and JAR hell, providing a more robust and scalable way to organize and deploy Java applications. Modules encapsulate packages and explicitly declare their dependencies, promoting better code organization and reducing runtime errors.
To create a module, we define a module-info.java file at the root of our source directory:
module com.myapp {
requires java.sql;
exports com.myapp.api;
}
This module declaration specifies that our module requires the java.sql module and exports the com.myapp.api package for use by other modules.
The introduction of the var keyword for local variable type inference in Java 10 has simplified code and improved readability. It allows the compiler to infer the type of a local variable based on the initializer expression:
var list = new ArrayList<String>();
var stream = list.stream();
This feature is particularly useful when working with complex generic types or when the type is evident from the context.
Java 11 brought us the convenient String methods strip(), stripLeading(), stripTrailing(), and isBlank(). These methods provide more robust alternatives to trim() for handling whitespace:
String text = " Hello, World! ";
System.out.println(text.strip()); // "Hello, World!"
System.out.println(text.stripLeading()); // "Hello, World! "
System.out.println(text.stripTrailing()); // " Hello, World!"
System.out.println("".isBlank()); // true
Another notable addition in Java 11 is the HttpClient API, which provides a modern, easy-to-use alternative to the older HttpURLConnection. It supports HTTP/2 and WebSocket, and offers both synchronous and asynchronous request handling:
HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
.uri(URI.create("https://api.example.com/data"))
.build();
HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
System.out.println(response.body());
Java 12 introduced switch expressions, which were further enhanced in Java 14. These allow us to use switch as an expression and eliminate the need for break statements:
String day = "MONDAY";
String type = switch (day) {
case "MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY" -> "Weekday";
case "SATURDAY", "SUNDAY" -> "Weekend";
default -> "Invalid day";
};
Text blocks, introduced as a preview feature in Java 13 and finalized in Java 15, simplify the creation of multi-line string literals. They eliminate the need for most escape sequences and preserve the intended indentation:
String json = """
{
"name": "John Doe",
"age": 30,
"city": "New York"
}
""";
Records, introduced in Java 14 as a preview feature and finalized in Java 16, provide a compact syntax for creating immutable data classes. They automatically generate constructors, accessors, equals(), hashCode(), and toString() methods:
public record Person(String name, int age) {}
Person person = new Person("John Doe", 30);
System.out.println(person.name()); // John Doe
Pattern matching for instanceof, introduced in Java 14 as a preview feature and finalized in Java 16, simplifies type checking and casting:
if (obj instanceof String s) {
System.out.println(s.length());
}
This eliminates the need for an explicit cast and reduces the risk of ClassCastExceptions.
Sealed classes, introduced in Java 15 as a preview feature and finalized in Java 17, allow developers to restrict which classes can extend a given class or implement an interface:
public sealed class Shape
permits Circle, Rectangle, Triangle {
// ...
}
public final class Circle extends Shape {
// ...
}
This feature provides more control over class hierarchies and can be particularly useful in domain modeling.
Finally, Java 16 introduced Stream.toList() as a convenient way to collect stream elements into a List:
List<String> list = Stream.of("a", "b", "c").toList();
This method is more concise than the previous approach of using collect(Collectors.toList()).
These features represent just a fraction of the improvements introduced in recent Java versions. As a developer, I’ve found that incorporating these new language constructs and APIs into my projects has significantly enhanced my productivity and code quality.
The modular system, for instance, has transformed how I structure larger applications. By explicitly declaring dependencies between modules, I’ve been able to create more maintainable and less error-prone codebases. The ability to encapsulate internal implementation details within a module has also improved the overall architecture of my applications.
Local variable type inference with var has been a game-changer for readability, especially when dealing with complex generic types. I’ve found that it reduces visual clutter without sacrificing type safety, as the compiler still performs all necessary type checks.
The new String methods have simplified many common text processing tasks. I no longer need to write custom utility methods or use regular expressions for basic string operations like trimming whitespace or checking if a string is blank.
The HttpClient API has become my go-to choice for making HTTP requests in Java applications. Its support for modern protocols and asynchronous operations has made it much easier to implement efficient network communication.
Switch expressions have eliminated a common source of bugs in my code - forgetting to add break statements in switch cases. The new syntax is more concise and less error-prone, and I’ve found it particularly useful when mapping enum values to other types.
Text blocks have been a boon when working with multi-line strings, especially when dealing with SQL queries, JSON, or HTML templates. They’ve eliminated the need for string concatenation or StringBuilder in many cases, resulting in more readable and maintainable code.
Records have simplified the creation of data transfer objects in my projects. I’ve found them particularly useful in REST API implementations, where I often need to create classes that are little more than grouped fields. The automatic generation of common methods saves time and reduces the potential for errors.
Pattern matching for instanceof has made my type-checking code more concise and safer. I’ve been able to eliminate many explicit casts, reducing the risk of runtime exceptions.
Sealed classes have given me more control over my class hierarchies. In domain modeling, I’ve used them to ensure that only a specific set of subclasses can exist, which has helped in maintaining the integrity of my object models.
The Stream.toList() method has simplified many of my stream operations. While it’s a small change, I’ve found that it makes my code more readable and reduces the cognitive load when working with streams.
In conclusion, these features represent a significant evolution in the Java language and platform. They address common pain points, improve code readability and safety, and provide developers with powerful new tools for building robust and efficient applications. As a Java developer, I’ve found that staying up-to-date with these features and incorporating them into my projects has not only improved my code but has also made the development process more enjoyable and productive.
It’s worth noting that the Java ecosystem continues to evolve rapidly. The six-month release cycle introduced with Java 9 means that new features and improvements are being added at a faster pace than ever before. While this can sometimes feel overwhelming, it also means that the language is becoming increasingly powerful and versatile.
As developers, it’s crucial that we stay informed about these changes and actively seek opportunities to apply them in our projects. This not only helps us write better code but also ensures that we’re taking full advantage of the language’s capabilities.
However, it’s equally important to approach new features judiciously. Not every new feature will be appropriate for every project or situation. It’s our responsibility as developers to evaluate each feature in the context of our specific needs and use cases.
For instance, while the module system offers significant benefits for large, complex applications, it may introduce unnecessary complexity for smaller projects. Similarly, while records are excellent for simple data classes, they may not be suitable for classes that require more complex behavior.
It’s also worth considering the broader ecosystem when adopting new features. If you’re working on a team or contributing to open-source projects, you’ll need to consider factors like the Java versions supported by your build tools, libraries, and deployment environments.
In my experience, the best approach is to start small. Introduce new features gradually, beginning with those that offer the most immediate benefits for your specific use cases. This allows you to gain experience with the new constructs and assess their impact on your codebase before committing to wider adoption.
Remember, too, that many of these features were introduced as preview features before being finalized. This gives us the opportunity to experiment with new language constructs and provide feedback to the Java community before they become permanent parts of the language.
As we look to the future, it’s clear that Java will continue to evolve. Upcoming versions promise even more exciting features, including pattern matching for switch statements, sealed interfaces, and improvements to concurrent programming constructs.
By staying informed about these developments and thoughtfully incorporating new features into our code, we can ensure that our Java applications remain modern, efficient, and maintainable. The features we’ve discussed in this article are just the beginning of what promises to be an exciting new era for Java development.
