Book Image

Java 11 and 12 ??? New Features

By : Mala Gupta
Book Image

Java 11 and 12 ??? New Features

By: Mala Gupta

Overview of this book

With its new six-monthly release cadence, Java is moving forward faster. In addition to planned version releases, a lot of work is currently being undertaken on various Java projects at Oracle. In order to make best use of the new features in their applications and libraries, you must be well-versed with the most recent advancements. Java 11 and 12 – New Features will take you through the latest developments in Java, right from variable type inference and simplified multithreading through to performance improvements, which are covered in depth to help you make your applications more efficient. This book explains the relevance and applicability of Java's new features, and answers your questions on whether to invest in migrating to new Java versions and when to migrate. You'll also get to grips with platform features, such as AppCDS and new garbage collectors, to tune and optimize your application—from reduced launch time and latency to improved performance and throughput. By the end of this book, you will be equipped with a thorough understanding of the new features of Java 11, 12, and Project Amber, and possess the skills to apply them with a view to improving your application's performance.
Table of Contents (23 chapters)
Free Chapter
1
Section 1: JDK 10
6
Section 2: JDK 11
13
Section 3: JDK 12
16
Section 4: Project Amber

Getting started with JFR

Let's get started with a simple HelloWorld example, as follows:

class HelloWorld { 
    public static void main(String[] args) { 
        System.out.println("Hello World - This is being recorded"); 
    } 
} 

To start flight recording for the preceding application, execute the following command on your console:

  > java -XX:StartFlightRecording,filename=hello.jfr 
     HelloWorld  

The first line instructs the Java Runtime to start flight recording for your HelloWorld application and save it to the HelloWorldRecording.jfr file.

There are three parts to the previous command, as follows:

  • Starting JFR with the -XX:StartFlightRecording JVM option
  • Specifying the target file to save the recording to hello.jfr
  • Specifying the application to run HelloWorld

Let's start MC to view the profiling data stored in hello.jfr. Use the jmc.exe file...