Book Image

Java 9 Programming Blueprints

By : Jason Lee
Book Image

Java 9 Programming Blueprints

By: Jason Lee

Overview of this book

Java is a powerful language that has applications in a wide variety of fields. From playing games on your computer to performing banking transactions, Java is at the heart of everything. The book starts by unveiling the new features of Java 9 and quickly walks you through the building blocks that form the basis of writing applications. There are 10 comprehensive projects in the book that will showcase the various features of Java 9. 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 a few. The book covers various libraries and frameworks in these projects, and also introduces a few more frameworks that complement and extend the Java SDK. Through the course of building applications, this book will not only help you get to grips with the various features of Java 9, but will also teach you how to design and prototype professional-grade applications with performance and security considerations.
Table of Contents (19 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback
Taking Notes with Monumentum

Building the command-line interface

The primary means to interact with our new library will be the command-line interface we will now develop. Unfortunately, the Java SDK has nothing built in to help make sophisticated command-line utilities. If you've been using Java for any time, you've seen the following method signature:

    public static void main(String[] args) 

Clearly, there is a mechanism to process command-line arguments. The public static void main method is passed string arrays that represent arguments provided by the user on the command line, but that's about as far as it goes. To parse the options, the developer is required to iterate over the array, analyzing each entry. It might look something like this:

    int i = 0; 
    while (i < args.length) { 
      if ("--source".equals(args[i])) { 
         System.out.println("--source = " + args[++i]); 
      } else if ("--target".equals(args[i])) { 
         System.out.println("--target = " + args[++i]); 
      } else if ("--force...