Preparing for an interview? Want to just revisit Java SE 9 features? Trying to recollect or revise Java SE programming constructs? Let me take you back in time to what was introduced first in Java SE 9? Join me for this tutorial series on Java as we all eagerly await the official release of Java SE 14!
As I promised, I am back with the code samples of my earlier article Java SE 9... What's New? You may refer the earlier article to understand the newly introduced features at a high level. This article provides the code samples for each of the features.
You may download the code samples for the following new features here. (Import as eclipse project, set compiler/environment as Java 9. Run the main class 'Java9Application' to see the output/outcome of the Code Samples.)
I plan to start by re-visiting a Java 8 feature, Default Interface Methods.
OpenJDK: More Speed, Less Haste
It's now over two years since the release of JDK 9, and with it, the switch to a time-based rather than feature-based release schedule. It seems incredible that it took very nearly eleven years to get from JDK 6 to JDK 9, yet in just over two years, we've gone from JDK 9 to JDK 13.
Each release under this new strategy provides a smaller set of features than we had in the old major release approach. What we're seeing, though, is the overall rate of change is faster than it's ever been, which is a significant advantage for keeping Java vibrant and attractive to developers.
Top Tutorials to Learn Java 9 Features in Depth
It’s been more than a year since JDK 9 was released, and if you haven't touched Java 9, this year is probably the best time to learn Java 9 and get yourself familiar with new features and enhancements on existing APIs. The highlight of JDK 9 release was Project Jigsaw or Module System.
The Java 9 Platform Module System allows Java to move forward by modularizing the JDK as well as adding modules as first-class citizens to Java, but that’s not the only thing to look forward, there are many small changes that are very useful in day-to-day coding.
JDK 9/JEP 280: String Concatenations Will Never Be the Same
JEP 280 ("Indify String Concatenation") was implemented in conjunction with JDK 9 and, according to its "Summary" section, "Change[s] the static String-concatenation bytecode sequence generated by javac to use invokedynamic calls to JDK library functions." The impact this has on string concatenation in Java is most easily seen by looking at the javap output of classes using string concatenation that is compiled in pre-JDK 9 and post-JDK 9 JDKs.
The following simple Java class named "HelloWorldStringConcat" will be used for the first demonstration.
Explicitly Naming Automatic Java Modules
Nicolas Fränkel recently published the surprising post "A hard look at the state of Java modularization." In that post, Fränkel provides the results of his investigation into support available in the 29 libraries referenced in the blog post "20 popular Java libraries" for modules introduced with JDK 9. Fränkel's investigation aimed to identify which of these popular Java libraries was "modularized" (fully implemented module defined in module-info.java) or provided at least an "automatic module name" via MANIFEST.MF even if the library isn't modularized.
Of the 29 popular Java libraries investigated, Fränkel identified only two (SLF4J 1.8.0-beta2 and JAXB 2.3.1) that are fully modularized. Of the remaining 27 libraries that are not fully modularized, 12 do have an automatic module name defined. That means, of course, that 15 of the 29 libraries (just over 50 percent) do not have any explicit support for modularity introduced with JDK 9!