OnJava8-Examples-master

# Examples for *On Java 8* by Bruce Eckel If you want to experiment with the code examples from the book [On Java 8](https://www.onjava8.com/), you're in the right place. These examples are automatically extracted directly from the book. This repository includes tests to verify that the code in the book is correct. > NOTE: Do not attempt to use JDK 16 or greater with gradle. > This produces a `BUG!` message from Gradle, which is broken for those versions. ## Contents - [Building From the Command Line: Quick Version](#building-from-the-command-line-quick-version) - [Building From the Command Line: Detailed Instructions](#building-from-the-command-line-detailed-instructions) * [Install Java](#install-java) + [Windows](#windows) + [Macintosh](#macintosh) + [Linux](#linux) * [Verify Your Installation](#verify-your-installation) * [Installing and Running the Book Examples](#installing-and-running-the-book-examples) - [Appendix A: Command-Line Basics](#appendix-a-command-line-basics) * [Editors](#editors) * [The Shell](#the-shell) + [Starting a Shell](#starting-a-shell) + [Directories](#directories) + [Basic Shell Operations](#basic-shell-operations) + [Unpacking a Zip Archive](#unpacking-a-zip-archive) - [Appendix B: Testing](#appendix-b-testing) - [Appendix C: Troubleshooting](#appendix-c-troubleshooting) # Building From the Command Line: Quick Version Before you can run the examples from this repository, you must install [JDK8](http://www.oracle.com/technetwork/java/javase/downloads/index.html), the *Java Development Kit* for version 8 of the language. If you just want to download and check the code, [Download Here](https://github.com/BruceEckel/OnJava8-Examples/archive/refs/heads/master.zip) and [unzip it](#unpacking-a-zip-archive) into your destination directory. Open a [shell/command window](#appendix-a-command-line-basics) and move into the root of that directory. You'll know you are in the right directory if you see the files `gradlew` and `gradlew.bat`. You'll need an Internet connection the first time you compile the code, because Gradle needs to first install itself, then all the support libraries. Once these are installed you can perform additional compiling and running offline. On Mac/Linux, enter: ``` ./gradlew test ``` (If you get a *Permission denied* error, run `chmod +x ./gradlew`) On Windows, enter ``` gradlew test ``` If all goes well, the tests will run. Everything should complete without errors. All the book examples are in the subdirectory `Examples` in subdirectories corresponding to the atom names. # Building From the Command Line: Detailed Instructions If you are not familiar with the command line, first read [Command-Line Basics](#appendix-a-command-line-basics). ## Install Java You must first install the *Java Development Kit* (JDK). ### Windows 1. Follow the instructions to [install Chocolatey](https://chocolatey.org/). 2. At a [shell prompt](#appendix-a-command-line-basics), type: `choco install jdk8` (you may also select a more recent version, like `jdk11`). The installation process takes some time, but when it's finished Java is installed and the necessary environment variables are set. ### Macintosh The Mac comes with a much older version of Java that won't work for the examples in this book, so you'll need to update it to (at least) Java 8. 1. Follow the instructions at this link to [Install HomeBrew](http://brew.sh/) 2. At a [shell prompt](#appendix-a-command-line-basics), first type `brew update`. When that completes, enter `brew cask install java`. **NOTE:** Sometimes the default version of Java that you get with the above installation will be too recent and not validated by the Mac's security system. If this happens you'll either need to turn off the security by hand or install an earlier version of Java. For either choice, you'll need to Google for answers on how to solve the problem (often the easiest approach is to just search for the error message produced by the Mac). ### Linux Use the standard package installer with the following [shell commands](#appendix-a-command-line-basics): *Ubuntu/Debian*: 1. `sudo apt-get update` 2. `sudo apt-get install default-jdk` *Fedora/Redhat*: ``` su -c "yum install java-1.8.0-openjdk" ``` ## Verify Your Installation [Open a new shell](#appendix-a-command-line-basics) and type: ``` java -version ``` You should see something like the following (Version numbers and actual text will vary): ``` openjdk version "11" 2018-09-25 OpenJDK Runtime Environment 18.9 (build 11+28) OpenJDK 64-Bit Server VM 18.9 (build 11+28, mixed mode) ``` If you see a message that the command is not found or not recognized, review the installation instructions. If you still can't get it to work, check [StackOverflow](http://stackoverflow.com/search?q=installing+java). ## Installing and Running the Book Examples Once you have Java installed, the process to install and run the book examples is the same for all platforms: 1. Download the book examples from the [GitHub Repository](https://github.com/BruceEckel/OnJava8-Examples/archive/refs/heads/master.zip). 2. [Unzip](#unpacking-a-zip-archive) the downloaded file into the directory of your choice. 3. Use the Windows Explorer, the Mac Finder, or Nautilus or equivalent on Linux to browse to the directory where you uzipped `OnJava8-Examples`, and [open a shell](#appendix-a-command-line-basics) there. 4. If you're in the right directory, you should see files named `gradlew` and `gradlew.bat` in that directory, along with numerous other files and directories. The directories correspond to the chapters in the book. 5. At the shell prompt, type `gradlew test` (Windows) or `./gradlew test` (Mac/Linux). The first time you do this, Gradle will install itself and numerous other packages, so it will take some time. After everything is installed, subsequent builds and runs will be much faster. Note that you must be connected to the Internet the first time you run `gradlew` so that Gradle can download the necessary packages. # Appendix A: Command-Line Basics Because it is possible for a "dedicated beginner" to learn programming from this book, you may not have previously used your computer's command-line shell. If you have, you can go directly to the [installation instructions](#building-from-the-command-line-detailed-instructions). ## Editors To create and modify Java program files—the code listings shown in this book—you need a program called an *editor*. You'll also need the editor to make changes to your system configuration files, which is sometimes required during installation. Programming editors vary from heavyweight *Integrated Development Environments* (IDEs, like Eclipse, NetBeans and IntelliJ IDEA) to more basic text manipulation applications. If you already have an IDE and are comfortable with it, feel free to use that for this book. Numerous explanations in this book are specific to IntelliJ IDEA so if you don't already have an IDE you might as well start with IDEA. There are many other editors; these are a subculture unto themselves and people sometimes get into heated arguments about their merits. If you find one you like better, it's not too hard to change. The important thing is to choose one and get comfortable with it. ## The Shell If you haven't programmed before, you might be unfamiliar with your operating system *shell* (also called the *command prompt* in Windows). The shell harkens back to the early days of computing when everything happened by typing commands and the computer responded by displaying responses—everything was text-based. Although it can seem primitive in the age of graphical user interfaces, a shell provides a surprising number of valuable features. To learn more about your shell than we cover here, see [Bash Shell](https://en.wikipedia.org/wiki/Bash_(Unix_shell)) for Mac/Linux or [Windows Shell](https:/