What Programmers Need to Know about Java 9?
- Module System
- Ahead-of-Time Compilation
- Real-Eval-Print-Loop Tool
- Improved Stream API
- Multi-Resolution Image API
- Stack-Walking API
- Datagram Transport Layer Security (DTLS) API
- Improved Process API
Each modular JAR file contains a module descriptor. The developers can define interdependency of various modules through requires statements.
The modularity makes it easier for programmers to run JVM modules smoothly on small devices that lack additional memory.
Java 9 improves code compilation process significantly through ahead-of-time (AOT) compilation.
The programmers can leverage AOT compilation compile Java classes into native code even before the virtual machine launches them.
AOT compilation improves the performance of both large and small applications by overcoming major shortcomings of just-in-time (JIT) compilation.
Unlike JIT compilation, AOT compilation ensures that no Java method remains uncompiled.
Java 9 comes with a new real-eval-print-loop (REPL) command line tool – Shell.
Shell is designed with features to evaluate declarative statements and expressions interactively.
A programmer can use Shell to assess the quality of Java code before compilation.
He can simply enter a piece of code and collect feedback. Shell even has the capability to complete tabs and add required terminal semicolons automatically.
The new REPL tool makes Java compete with widely used programming languages like Python and Scala.
Improved Stream API
While writing Java code, programmers use strings to express calculations. Java 8 accelerated stream processing by providing the Streams API. Java 9 comes with an improved version of the Streams API that enables developers to take and drop items from Stream based on specific conditions by adding methods. Also, the improved Streams API is designed with features to create a stream for nullable value and iterate over Stream elements.
Multi-Resolution Image API
Java 9 introduces a new interface – MultiResolutionImage – to create a single multi-resolution image by encapsulating multiple images with varying resolutions. The developers can further use the Multi-Resolution Image API provided by Java 9 to get various variants of a single image. Also, they can use the API to select a particular image based on the required resolution. Hence, the Java programmers can now use a single API to create a unified multi-resolution image and get resolution-specific image variants.
http://2 client API
Java 9 completely changed the way applications make HTTP calls. It replaces the HttpURLConnection API with a new HTTP client API. The HTTP client API supports both http://2 and WebSockets. However, the API is currently not a part of Java SE. It is implemented as an incubator module which lives under the jdk.incubtor namespace. But the HTTP client API supports the latest communication standards, while overcoming the shortcomings of the HttpURLConnection API.
While writing Java code, programmers explore ways to access and filter stack trances efficiently. The latest version of Java simplifies stack walking by providing the Stack-Walking API. The new API makes it easier for programmers to access and filter stack trace information. It further supports both short and long walks. Hence, it becomes easier for programmers to access and filter the entire stack without relying on the virtual machine to capture the stack information.
Datagram Transport Layer Security (DTLS) API
Java 9 helps developers to build secure applications by providing an API for Datagram Transport Layer Security (DTLS). The API keeps client and server communication secure by eliminating chances of data tampering, message forgery, and eavesdropping. Also, it provides communication privacy to a variety of applications that use Datagram Transport Protocol (DTP). Despite being developed based on Transport Layer Security (TLS), DTLS implements SSL protocol.
Improved Process API
Often Java programmers find it daunting to control and manage operating system processes. The Process API provided by earlier version of developers to access the native code and write additional code.
But the improved Process API provided by Java 9 makes it easier for programmers to control and mange operating system processes.
They can use the API to make a Java application interact with the operating system directly. Also, they can take advantage of the new methods to handle process names and states without writing additional code.
Despite providing several new features, Java 9 does not support some of the features provided by Java 8.
For instance, it no longer supports Applet API.
The Java web developers have to switch from Applet API to Java Web Start to launch applications from web browsers.
Likewise, Java 8 speeds up development of garbage collectors in HotSpot virtual machine by deprecating Concurrent Mark Sweep (CMS) garbage collectors.
While using the most recent version of Java, programmers also lack option to receive Java warnings on import statements and select JRE at launch time.