Book Image

The Java Workshop

By : David Cuartielles, Andreas Göransson, Eric Foster-Johnson
Book Image

The Java Workshop

By: David Cuartielles, Andreas Göransson, Eric Foster-Johnson

Overview of this book

Java is a versatile, popular programming language used across a wide range of industries. Learning how to write effective Java code can take your career to the next level, and The Java Workshop will help you do just that. This book is designed to take the pain out of Java coding and teach you everything you need to know to be productive in building real-world software. The Workshop starts by showing you how to use classes, methods, and the built-in Collections API to manipulate data structures effortlessly. You’ll dive right into learning about object-oriented programming by creating classes and interfaces and making use of inheritance and polymorphism. After learning how to handle exceptions, you’ll study the modules, packages, and libraries that help you organize your code. As you progress, you’ll discover how to connect to external databases and web servers, work with regular expressions, and write unit tests to validate your code. You’ll also be introduced to functional programming and see how to implement it using lambda functions. By the end of this Workshop, you’ll be well-versed with key Java concepts and have the knowledge and confidence to tackle your own ambitious projects with Java.

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The Java Workshop
David Cuartielles | Andreas Göransson | Eric Foster-Johnson
Oct, 2019 | 606 pages
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Table of Contents (20 chapters)
Preface
Preface
About the Book
Free Chapter
1
1. Getting Started
1. Getting Started
Introduction
Writing, Compiling, and Executing Your Hello World Program
Summary
2
2. Learning the Basics
2. Learning the Basics
Introduction
Controlling the Flow of Your Programs
Looping and Performing Repetitive Tasks
Handling Command-Line Arguments
Summary
3
3. Object-Oriented Programming
3. Object-Oriented Programming
Introduction
Working with Objects in Java
Checking the Precedence of a Class with instanceof
Inheritance in Java
Overriding and Hiding Methods
Overloading Methods and Constructors
Recursion
Annotations
Interfaces
Inner Classes
Documenting with JavaDoc
Summary
4
4. Collections, Lists and Java's Built-In APIs
4. Collections, Lists and Java's Built-In APIs
Introduction
Arrays
Sets
Lists
Maps
Iterating through Collections
Sorting Collections
Properties
Summary
5
5. Exceptions
5. Exceptions
Introduction
A Simple Exception Example
NullPointerException – Have No Fear
Catching Exceptions
Throws and Throw
The finally Block
Best Practices for Handling Exceptions
Where Do Exceptions Come from?
Summary
6
6. Libraries, Packages, and Modules
6. Libraries, Packages, and Modules
Introduction
Organizing Code into Packages
Summary
7
7. Databases and JDBC
7. Databases and JDBC
Introduction
Relational Databases
Relational Database Management Systems
Introducing SQL
Summary
8
8. Sockets, Files, and Streams
8. Sockets, Files, and Streams
Introduction
Listing Files and Directories
Creating and Writing to a File
Reading an Existing File
Reading a Properties File
Summary
9
9. Working with HTTP
9. Working with HTTP
Introduction
Exploring HTTP
Using HttpUrlConnection
Dealing with Slow Connections
Creating HTTP POST Requests
Parsing HTML Data
Delving into the java.net.http Module
Summary
10
10. Encryption
10. Encryption
Introduction
Symmetric Key Encryption
Block Ciphers
Asymmetric Key Encryption
Encrypting Files
Summary
11
11. Processes
11. Processes
Introduction
Launching a Process
Capturing the Output of a Child Process
Storing the Output of a Child Process in a File
Summary
12
12. Regular Expressions
12. Regular Expressions
Introduction
Decrypting Regular Expressions
Regular Expressions in Java
Summary
13
13. Functional Programming with Lambda Expressions
13. Functional Programming with Lambda Expressions
Introduction
Functional Programming
Pure Functions
Lambda Expressions
Summary
14
14. Recursion
14. Recursion
Introduction
Delving into Recursion
Summary
15
15. Processing Data with Streams
15. Processing Data with Streams
Introduction
Creating Streams
Intermediate Operations
Using Collectors
Summary
16
16. Predicates and Other Functional Interfaces
16. Predicates and Other Functional Interfaces
Introduction
Predicate Interface
Activity 1: Toggling the Sensor States
Function
Summary
17
17. Reactive Programming with Java Flow
17. Reactive Programming with Java Flow
Introduction
Publisher
Subscriber
Processor
Summary
18
18. Unit Testing
18. Unit Testing
Introduction
Getting Started with Unit Tests
Summary
Appendix
Appendix
1. Getting Started
2. Learning the Basics
3. Object-Oriented Programming
4. Collections, List, and Java's Built-In APIs
5. Exceptions
6. Libraries, Packages, and Modules
7. Databases and JDBC
8. Sockets, Files, and Streams
9. Working with HTTP
11. Processes
12. Regular Expressions
13. Functional Programming with Lambda Expressions
14. Recursion
15. Processing Data with Streams
16. Predicates and Other Functional Interfaces
17. Reactive Programming with Java Flow
18. Unit Testing
What Next?

Processor

The Processor is something of a chameleon in Flow; it may act as both a Subscriber and a Publisher.

There are several different reasons for adding an interface such as the Processor. One reason may be that you have a stream of data that you do not fully trust. Imagine an asynchronous flow of data from a server, where data is delivered over a UDP connection that lacks promises of delivery; this data will eventually be corrupted and you need to handle that. A simple way would be to inject a filter of some kind between the publisher and subscriber. This is where a Processor excels.

Another reason for using a Processor could be to separate a polymorphic data stream between different subscribers so that alternative actions may be taken based on the data type.

Exercise 2: Using a Processor to Convert a Stream of Strings to Numbers

In this exercise, we will first build a Publisher that periodically publishes a string from a text file. Then, we will use a scheduler to...

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