Book Image

Java 9: Building Robust Modular Applications

By : Dr. Edward Lavieri, Peter Verhas, Jason Lee
Book Image

Java 9: Building Robust Modular Applications

By: Dr. Edward Lavieri, Peter Verhas, Jason Lee

Overview of this book

Java 9 and its new features add to the richness of the language; Java is one of the languages most used by developers to build robust software applications. Java 9 comes with a special emphasis on modularity with its integration with Jigsaw. This course is your one-stop guide to mastering the language. You'll be provided with an overview and explanation of the new features introduced in Java 9 and the importance of the new APIs and enhancements. Some new features of Java 9 are ground-breaking; if you are an experienced programmer, you will be able to make your enterprise applications leaner by learning these new features. You'll be provided with practical guidance in applying your newly acquired knowledge of Java 9 and further information on future developments of the Java platform. This course will improve your productivity, making your applications faster. Next, you'll go on to implement everything you've learned by building 10 cool projects. You will learn to build an email filter that separates spam messages from all your inboxes, a social media aggregator app that will help you efficiently track various feeds, and a microservice for a client/server note application, to name just a few. By the end of this course, you will be well acquainted with Java 9 features and able to build your own applications and projects. This Learning Path contains the best content from the following two recently published Packt products: • Mastering Java 9 • Java 9 Programming Blueprints
Table of Contents (33 chapters)
Title Page - Courses
Packt Upsell - Courses
Taking Notes with Monumentum

JVM command-line flag argument validation [JEP 245]

In this chapter, you have gained exposure to much of the command-line flag usage with the Java 9 platform. Java Enhancement Proposal 245, titled Validate JVM Command-Line Flag Arguments, was created to ensure all JVM command-line flags with arguments are validated. The primary goals of this effort were:

  • Avoid JVM crashes
  • Provide error messages to inform of invalid flag arguments

As you can see from the following graphic, there was no attempt to auto-correct the flag argument errors; rather, just to identify the errors and prevent the JVM from crashing:

A sample error message is provided here and indicates that the flag argument was out of range. This error would be displayed during the flag argument range check performed during the JVM's initialization:

exampleFlag UnguardOnExecutionViolation = 4 is outside the allowed range [ 0 . . . 3]

Here are some specifics regarding this change to the Java platform:

  • Expand on the current globals.hpp source...