Java is handy for programmers; they need only write a program once and not worry about whether the user has a PC or a Mac computer, or be concerned with which browser is being used. Java applications can be embedded in web pages, cell phones, industrial controls, household thermostats, even coffee makers. A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describes what is required in a JVM implementation.

This DrJava-based Java programming environment is no longer being supported(because DrJava in no longer being actively developed and DrJava is incompatible with Java 11).It has been replaced by the following IntelliJ-based programming environment forMac OS X.

This document instructs you on how to set up our Java programming environment for your Mac OS X computer. It also provides a step-by-step guide for creating, compiling, and executing a Java program using either DrJava or the Terminal.All of the software used is freely available.

You will need an Intel-based Mac runningMac OS X 10.8 (Mountain Lion) to Mac OS X 10.13 (High Sierra).

You can defer steps 4–6 until Section 1.5 of the textbook.

0. Install the Programming Environment

Our installer downloads, installs, and configures the Java programming environment you will be using, including DrJava, and the standard libraries from our textbook.

Log in to the user account in which you will be programming.Your account must have Administrator privileges (with a non-blank password)and you must be connected to the Internet.
Install Oracle's implementation of the Java Platform, Standard Edition Development Kit (JDK 8).Do not install either JDK 9 or JDK 10, as they are currently incompatible with DrJava.
- Browse toJava SE Development Kit 8u171.In the first table, check Accept License Agreementand the click jdk-8u171-macosx-x64.dmg,which corresponds to the entry for Mac OS X.The exact verison 8u171 is not essential.
- Double click the downloaded file jdk-8u171-macosx-x64.dmg to begin the installation.Enter your OS X password when prompted.We recommend all of the default options.
- Delete jdk-8u171-macosx-x64.dmg.
To install,
- Download introcs.zip to the Desktop;double-click it to unzip (if necessary). This creates introcs.app. Security and Privacy -> General -> Allow applications downloaded from: Anywhere.
  To enable this option, you may need to click the lock in the lower left-hand corner(and type your password when prompted).-->
- Double-click introcs.app to perform the installation.If you receive a warning that introcs.app is an applicationdownloaded from the Internet, click Open.
- Enter your OS X password when prompted.
If the installation succeeds, you will see the following:
- A Terminal window containing approximately thisexecution log.
- A Standard Drawing window containing a red bullseye and a textbook graphic.
Delete introcs.zip and introcs.app.

1. Create the Program in DrJava

Now you are ready to write your first Java program.You will develop your Java programs in an application called DrJava.DrJava features many specialized programming tools including syntax highlighting,bracket matching, auto indenting, and line numbering.

The installer creates a shortcut to DrJava on the desktop.Double-click it to launch DrJava.If you receive a warning about incoming network connections,click Allow.
In the main DrJava window, type the Java programHelloWorld.java exactly as it appears below. If you omit even a semicolon, the program won't work. As you type, DrJava does the indenting for you.
Finally, click the Save button to save the file, using the name HelloWorld.java.The filename is case sensitive and must exactly match the name of theclass in the Java program.

2. Compile the Program in DrJava

It is now time to convert your Java program into a form more amenable for execution on a computer. To do this, click the Compile button.If all goes well, you should see the following message in the Compiler Outputpane at the bottom:

If DrJava complains in some way, you mistyped something.Check your program carefully, using the error messages in the Compiler Output paneas a guide.

3. Execute the Program in DrJava

Now it is time to run your program. This is the fun part.

Type the following in the Interactions pane at the bottom.By convention, we highlight the text you type in boldface. If all goes well, you should see the following message:
You may need to repeat this edit–compile–execute cycle a few times before it works. Ask for help if you can't see the mistake.

Congratulations, you are now a Java programmer!

4. Command-Line Interface with the Terminal

The command-line provides capabilities beyond those available in DrJava,including redirection and piping.You will type commands in an application called the Terminal.

The installer creates a shortcut on the desktop to the Terminal.Double-click it to launch the Terminal.You should see something like:The ~ is shorthand for your home directory /Users/<username>.
To confirm that the Java compiler is installed,type the command in boldface below and check that the results match:It's important that you see the number 1.8for the Java version number, but the rest is not critical.
To confirm that you the Java interpreter is installed, typethe command in boldface below and check that the results match:Again, it's important that you see the number 1.8for the Java version number, but the rest is not critical.

5. Compile the Program from the Terminal

You will use the javac command to convert your Java program into a form more amenable for execution on a computer.

From the Terminal, navigate to the directory containing HelloWorld.java,say ~/Desktop/hello,by typing the cd (change directory) commands below:The ~ is shorthand for /Users/<username>.
Compile it by typing the javac command below:Assuming the file HelloWorld.java is in the current working directory,you should see no error messages.
To make our textbook standard libraries accessible to Java,use the command javac-introcs instead.For example,BouncingBall.javais a program that uses our standard drawing library.After downloading the file to the current directory,you can compile it with the following command:

What Is Java Used For On Mac