Chapter 2. Tools for Higher Productivity and Faster Application

Since the dawn of programming as a profession, the standing goals of every aspiring coder were to quickly produce applications that perform the assigned tasks with lightning speed. Otherwise, why bother? We could slowly do whatever we were doing for thousands of years. In the book of the last century, we made substantial progress in both aspects, and now, Java 9 makes another step in each of these directions.

Two new tools were introduced in Java 9, JShell and the Ahead-of-Time (AOT) compiler--both were expected for a long time. JShell is a Read–Eval–Print Loop (REPL) tool that is well-known for those who program in Scala, Ruby, or Python, for example. It takes a user input, evaluates it, and returns the result immediately. The AOT compiler takes Java bytecode and generates a native (system-dependent) machine code so that the resulting binary file can execute natively.

These tools will be the focus of...