Java 17, though a significant release, might not be the “next evolution” in programming as it was released in September 2021 and has since been superseded by newer versions. However, it did introduce some noteworthy Java 17 exploring features that are still relevant today. Here’s a quick rundown:
What is the Java 17 Version?
The Java Platform, Standard Edition 17 Development Kit (JDK 17) represents a feature-rich release of the Java SE platform, incorporating various enhancements and additions across multiple functional domains.
Explore the links available on this page to access the Release Notes, offering comprehensive insights into significant changes, enhancements, deprecated APIs and features, removed APIs and features, and other critical information pertaining to JDK 17 and Java SE 17.
Additionally, you’ll find links to supplementary sources of information about JDK 17. Navigate to the JDK 17 Guides and Reference Documentation link for access to user guides, troubleshooting resources, and targeted information aimed at assisting users transitioning from earlier JDK versions.
Key Features of Java 17:
- Enhanced Performance: Java 17 improved floating-point calculations and introduced better random number generators.
- Modernized Look for macOS Apps: Java applications running on macOS devices leverage the Metal API instead of the older OpenGL, resulting in a more polished look.
- Improved Security: As a Long-Term Support (LTS) release, Java 17 received regular security updates until September 2024.
Some features marked for removal in future releases:
- Applet API: This functionality, used for creating applets within web browsers, is deprecated due to its low usage and lack of support in modern browsers.
- RMI Activation: This remote method invocation mechanism needs to be updated with the rise of web technologies.
What is the Difference Between Java 17 and Java 8?
Java 8 brought about a paradigm shift in Java programming with the introduction of lambda expressions and streams, promoting functional programming and performance enhancements.
On the other hand, Java 17, designated as a Long-Term Support (LTS) version, presents a range of sophisticated features, such as sealed classes, pattern matching, and refined switch expressions, alongside notable advancements in garbage collection and overall system performance.
Compared to Java 8, Java 17 encompasses a multitude of performance enhancements. These include optimizations within the JVM, refinements in garbage collection strategies, and the incorporation of new language features aimed at facilitating the creation of more efficient code.
Latest Features of Java 17
Limited the implementation with Sealed classes and interfaces
Sealed classes, initially introduced as a preview feature in JDK 15 and now fully incorporated in JDK 17, address a longstanding concern regarding inheritance. Unlike traditional inheritance, which permits an unrestricted number of implementations, sealed classes offer a solution by allowing developers to constrain implementations. Essentially, sealed classes empower developers to dictate which classes or interfaces can extend or implement them, thereby exerting control over class hierarchies.
In practical terms, sealed classes establish restricted class hierarchies, granting oversight over inheritance. When declaring a sealed class, all immediate subclasses must be explicitly known at compile-time, and external clients cannot extend a sealed class in their codebase. Transforming a Java class into a sealed one involves adding the sealed modifier to its declaration, with keyword permits used to specify the classes permitted to extend the given sealed class.
Sealed class Fruit specifies three permitted subclasses, Square, Rectangle, and Circle:
public sealed class Shape permits, Square, Rectangle, Circle { }
2. Using Null in Switch Case is Now Legal
In previous versions of Java, leaving the selector expression null in a switch statement or expression would typically result in a NullPointerException, necessitating explicit handling to avoid potential runtime errors. However, Java 17 introduces a novel feature aimed at addressing this issue. Now, developers can utilize null as a selector expression in switch case expressions, eliminating the need for additional error-handling measures.
switch(checkNumber) {
case 1,7 -> System.out.println(“odd number”) ;
case 2,8 -> System.out.println(“even number”) ;
case null -> System.out.println(“Not defined”) ;
default -> System.out.println(“not a number”) ;
}
In this scenario, the variable checkNumber receives a numerical input. If the input happens to be null, the program outputs “Not defined.” It’s important to note that for cases 1 and 7, as well as cases 2 and 8, the selector expression should encompass other odd and even numbers, respectively, to ensure the code functions correctly. For the sake of simplicity, only a few numbers are included in the example.
3. End of Guessing the Cause of Null Pointer Exception
Whether it’s managing linked lists or dealing with code snippets containing object references, there’s always a lurking risk of encountering a null object reference, which can potentially bring operations to a halt if not handled meticulously. While debugging and Java logs can offer assistance, the debugging process itself is often time-consuming, and Java logs may only sometimes provide sufficient details regarding the specific null object causing a NullPointerException.
Enter Java 17’s NullPointerException guidance feature, a welcome ally indeed. This feature offers precise identification of the null variable directly from the exception’s stack trace. By pinpointing the exact variable name associated with the null reference, this feature alleviates the burden of tedious debugging and eliminates the guesswork involved in identifying the null pointer.
4. Redefining Switch Statement Expressions
The absence of a single break statement among multiple lines of switch-case statements can lead to unwelcome errors. Additionally, the repetitive case-break pattern can become cumbersome, especially when dealing with numerous switch cases. Fortunately, Java has addressed these concerns with the introduction of new switch statement expressions in Java 17.
These new switch expressions are designed to be cleaner and more straightforward, reducing the likelihood of errors. By utilizing arrow symbols, the new syntax eliminates fall-through functionality, enhancing readability and ease of debugging.
Moreover, it’s now possible to include multiple values within the same block by separating them with commas. One notable addition is the introduction of the yield keyword. In the following code snippet, when the default statement is executed, System.out.println() will be executed, resulting in the identifyTyres variable being assigned “Unknown Vehicle,” as intended by the default case’s yield behavior.
String identifyTyres = switch (vehicle) {
case Car -> “four”;
case Bike, Cycle -> “two”;
case Autorickshaw -> “three”;
default -> { System.out.println(“The vehicle could not be found.”);
yield “Unknown Vehicle”;
};
5. Removing Code Lines with Record Classes
Previewed in Java 14, record classes offer a welcome respite from the complexity of traditional POJO code. With records, even the most convoluted and unwieldy POJOs can be elegantly represented. These classes are both immutable and final, meaning their fields cannot be altered after instantiation, and they cannot be extended.
Records excel as data-only classes, effectively managing the boilerplate code associated with POJOs. They shine particularly when the goal is to store immutable data temporarily. In a given code snippet, ‘Data’ is an example of a record, with ‘a’ and ‘b’ being referred to as its components.
When defining a record, Java automatically generates implementations for methods like equals(), hashCode(), and toString(). This means that upon instantiation, developers receive pre-implemented methods for comparing records, generating hash codes, and displaying record components along with their respective names.
record Data(long a, long b) { }
The above Record Data is equivalent to the following lines of code:
public final class Data {
private final long a;
private final long b;
Public Data(long a, long b) {
this.a = a;
this.b = b;
}
long a() { return this.a; }
long b() { return this.b; }
// Implementation of equals() and hashCode(), which specify
public boolean equals…
public int hashCode…
// An implementation of toString() that returns a string
public String toString() {…}
}
The Final Thought!
Java has shifted to a new release cadence with LTS versions every two years. So, the next LTS version after Java 17 was Java 21, released in September 2023. It’s always recommended to use the latest LTS version for your projects to benefit from the newest features and security patches.
