This chapter covers key concepts and tools used to ease migration to JDK 9. It covers common issues that can occur when we migrate existing Java applications to JDK 9 and suggests solutions and tips for solving migration problems.
First, why do we need migration? The answer is obvious: without migrating to JDK 9, we can’t use the powerful features introduced by Jigsaw, nor can we use the other features introduced in Java 9 by the other JEPs, like the following:
The Java Shell
The updates in the Process API
The HTTP 2 client
The Stack-Walking API
The Platform Logging API
The multi-release JAR files ...