Java 11 Vs. Java 17: What Features Are Different & How Do They Compare?

Java has been one of the more popular programming languages and computing platforms on the market since Sun Microsystems released it all the way back in 1995. The free-to-download platform has been used in all kinds of fields over the years and is widely available on all kinds of platforms — even some mobile apps. Java has continued to evolve, offering new features and refining old ones. Java 11 first launched in September 2018 and received no fewer than 25 different updates over the following six years. This consistent commitment to staying at the forefront of the industry is one of the main reasons that so many software developers use Java as the cornerstone of their app development process. But now Java 11 has gotten quite old, leading some users to turn to the newer Java 17, the next version with long-term support (LTS). Premier support for Java 11 ended in September 2023, though its extended support will last until January 2032.

New technology can be fickle, however, and it's not always ideal to jump ship for the shiny new software and leave behind the familiar one right away (just look at Windows 11). That said, there are a lot of things to be excited about in Java 17. Those who have worked with Java 11 for a long time might be curious to know what changes the company has made and how this new platform compares to its predecessor. There are too many small changes to list, but it's worth taking a look at some of the bigger ones.

Several functional changes have been made in the coding language between Java 11 and Java 17. One of the biggest of these was the decision to add text blocks. These were originally added as a preview in Java 13 before they were finalized as a permanent feature in Java 15.

A text block is a syntax opening with a triple double quote followed by a line terminator. All the code that you add after this will be part of a single string until you use another triple double quote to close it. According to Oracle, "A text block's principalis munus is to provide clarity by way of minimizing the Java syntax required to render a string that spans multiple lines." This allows you to write multiline string literals in a much more concise manner, helps make the code more easily readable, and helps the coder reduce unnecessary excess string formatting. This is particularly useful when handling big sections of text such as you might find in HTML, JSON, and SQL queries.

In addition to being easier to read, text blocks are also a bit easier to write. They preserve leading and trailing spaces and allow the compiler to handle indentation automatically. This is much simpler than concatenating strings using + operators and then manually aligning them to the same indentation, saving the coder time and effort while minimizing the margin of error.

Another improvement that was made between Java 11 and Java 17 is in the way the language uses switch statements. These were first improved in Java 12 and then further refined in Java 13. See, the issue with the traditional switch statements in Java 11 and older versions is that their fall-through behavior is prone to error. Missing even a single break statement can lead to failed block execution. They also did not support the ability to have multiple values in a single case.

Post-Java 13 language models have received several upgrades. They support the ability to enter multiple case values, they utilize a new keyword, "yield," which returns values from a switch branch without needing to add a break, they use the switch as an expression that can return values in response to user input, they use switch expressions to return values and exceptions, they introduce the arrow syntax, which allows the switch to be used as an expression in addition to a statement, they allow you to use curly brackets to use variables on a case-level scope, and they add a useful preview feature.

According to the blog of software engineer Bruno Zambiazi, even more new features have been added in Java 17, "enhancing its functionality and making code more expressive. These changes aim to simplify the syntax, improve readability, and provide developers with more flexibility in handling complex scenarios." They state that the new syntax removes the need for break statements altogether, which enhances readability.

Records is another new feature that was introduced after Java 11. It was first released as a preview in Java 14 and became a standard feature in Java 16. Records are designed to help coders model data aggregates much more easily than they could with normal classes. As Oracle states, "A record declaration specifies in a header a description of its contents; the appropriate accessors, constructor, equals, hashCode, and toString methods are created automatically. A record's fields are final because the class is intended to serve as a simple 'data carrier.'"

A record class declaration is composed of three components: a name with optional type parameters, a header that lists the record's components, and a body. This automatically declares a canonical constructor, implementations of the "equals" and "hashCode" methods, and an implementation of the "toString" method. Each header also automatically declares a "private final" field and a "public accessor" method. Record classes also allow you to create record objects by using the keyword "new." This makes them a valuable addition to Java 17.

Another type of class that wasn't in Java 11 but that you will find in Java 17 is sealed classes. Sealed classes and interfaces are designed to allow you to control which of the other classes are allowed to be extended or implemented. This allows you to group classes together and determine which classes are allowed to be part of that grouping and which classes are excluded from it.

You can declare a sealed class by adding the "Sealed" modifier to its declaration. After you've done this, add the "permits" clause after any "extends" or "implements" clauses, thereby specifying the classes that extend the sealed class. By doing this, you can group these classes together in a manner that allows the compiler to run more effectively. "When a class is declared as sealed, the Java compiler performs additional checks to ensure that all the permitted subclasses are either final, sealed, or non-sealed," says backend developer Abhijeet Gite's Medium blog. "This is a compile-time check, ensuring the integrity of the class hierarchy." Sealed classes are also marked with metadata that the JVM and several other tools use to understand and execute the contract forged by the sealed class.

On top of that, sealed classes can be used to enforce design constraints, making the design easier to maintain. They can also improve security by preventing unwanted extensions and performance by allowing the compiler to optimize the code by recognizing all of the possible subclasses.

The "instanceof" operator existed in Java 11 as a means of checking whether an object belongs to a certain class. This is still how it is used in the later version, but a few improvements have been made to the tool that expand its capabilities. According to Oracle, "A pattern is a combination of a predicate, or test, that can be applied to a target and a set of local variables, called pattern variables, that are assigned values extracted from the target only if the test is successful." Pattern matching is a tool that can identify these patterns and streamlines the way "instanceof" checks an object's type and then uses it. It tests whether an object has an identifiable structure and then extracts the object's data if it does. This utility was first introduced in Java 16 and has been further improved in Java 17.

In Java 11, you would need to use "instanceof" to verify an object's type and then write a separate command to cast the object as its identified type. The pattern matching function in Java 17 allows you to skip this second step, making the code shorter, safer, and more readable.

Java isn't just used on Windows or Linux operating systems, it's also frequently used to develop software for Macs. Apple might have its own open-source coding language now in Swift, but many developers still use Java. So, it's important that Java can effectively render graphics on the macOS platform. This involves geometry processing, rasterization, texturing, shading, and compositing images. It was already able to do this in Java 11, but one of the bigger changes that came about with Java 17 was a brand-new macOS rendering pipeline that refines this technology even further.

The older version of the pipeline used the deprecated Apple OpenGL API (which may not be around for much longer), but the new Java 2D pipeline renders macOS graphics using the Apple Metal API which the company describes as "a modern, tightly integrated graphics and compute API coupled with a powerful shading language that is designed and optimized for Apple platforms." This API adds unified shaders, device initialization, gaming features, and machine learning technology.

In terms of how it affects Java, the new pipeline boosts performance with faster rendering and lower latency responsiveness, supports modern macOS features that might no longer support programs made using the OpenGL API, and future-proofs programs for future applications that will require features that are only present in the Metal API. OpenJDK states that one of the primary goals of the new pipeline is to create clean architecture that also coexists with the OpenGL pipeline until it's deemed completely obsolete.