Mac For Java Programming

This document instructs you on how to set up a Java programming environment for your Mac OS X computer. It also provides a step-by-step guide for creating and compiling a Java program in IntelliJ and executing it from the command line. You will need a Mac running Mac OS X 10.13 (High Sierra) to Mac OS X 10.15 (Catalina). Java Program to Shutdown Computer. To shutdown your computer using Java Programming, you have to use the command i.e. Java programming is a great thing to learn - and your Mac is the perfect place to get started. Java is by far the most popular programming language in the world, and OS X is a fantastic. The Java properties indicate the location of the jar file, the name of the Main class, and the version of the JRE to be used. The other properties include a pointer to the icon file and to the Java application stub file that is the native executable. Creating Mac OS X Java Applications on Other Platforms.

In this section, our plan is to lead you into the world of Java programming by taking you through the three basic steps required to get a simple program running. As with any application, you need to be sure that Java is properly installed on your computer.You also need an editor and a terminal application. Here aresystem specific instructions for three popular home operating systems.[Mac OS X ·Windows ·Linux]

Programming in Java.

We break the process of programming in Java into three steps:

Create the program by typing it into a text editor andsaving it to a file named, say, MyProgram.java.
Compile it by typing 'javac MyProgram.java' in theterminal window.
Execute (or run) it by typing'java MyProgram' in the terminal window.

The first step creates the program; the second translates it into a languagemore suitable for machine execution (and puts the result in a file namedMyProgram.class); the third actually runs the program.

Creating a Java program.A program is nothing more than a sequence of characters, like a sentence, aparagraph, or a poem. To create one, we need only define that sequence charactersusing a text editor in the same way as we do for email.HelloWorld.java is an example program.Type these character into your text editor and save it into a filenamed HelloWorld.java.
Compiling a Java program.A compiler is an application that translates programs from theJava language to a language more suitable for executing on the computer.It takes a text file with the .java extension as input (yourprogram) and produces a file with a .class extension (the computer-language version). To compile HelloWorld.java typethe boldfaced text below at the terminal. (We use the % symbolto denote the command prompt, but it may appear different dependingon your system.)If you typed in the program correctly, you should see no error messages.Otherwise, go back and make sure you typed in the program exactly asit appears above.
Executing (or running) a Java program.Once you compile your program, you can execute it.This is the exciting part, where the computer follows your instructions.To run the HelloWorld program, type the following in the terminal window:
If all goes well, you should see the following response
Understanding a Java program.The key line with System.out.println() prints the text 'Hello, World'in the terminal window.When we begin to write more complicated programs, we will discuss themeaning of public,class, main,String[],args,System.out, and so on.
Creating your own Java program.For the time being, all of our programs will be just likeHelloWorld.java, except with a different sequence of statementsin main(). The easiest way to write such a program is to:
- Copy HelloWorld.java into a new file whose name is theprogram name followed by .java.
- Replace HelloWorld with the program name everywhere.
- Replace the print statement by a sequence of statements.

Errors.

Most errors are easily fixed by carefully examining the program as wecreate it, in just the same way as we fix spelling and grammatical errors when we type an e-mail message.

Compile-time errors.These errors are caught by the system when we compile the program, because they prevent the compiler from doing the translation (so it issues an error message that tries to explain why).
Run-time errors.These errors are caught by the system when we execute the program, because the program triesto perform an invalid operation (e.g., division by zero).
Logical errors.These errors are (hopefully) caught by the programmer when we execute the programand it produces the wrong answer.Bugs are the bane of a programmer's existence.They can be subtle and very hard to find.

One of the very first skills that you will learn is to identify errors;one of the next will be to be sufficiently careful when coding to avoid many of them.

Input and output.

Typically, we want to provide input to our programs:data that they can process to produce a result. The simplest way to provide input data is illustrated in UseArgument.java.Whenever this program is executed, it reads the command-line argument that you type after the program name and prints it back out to the terminal as part of the message.

Exercises

Write a program TenHelloWorlds.javathat prints 'Hello, World' ten times.
Modify UseArgument.java to make a programUseThree.java that takes three namesand prints out a proper sentence with the names in the reverse of the order given, so that for example,'java UseThree Alice Bob Carol'gives 'Hi Carol, Bob, and Alice.'.

Web Exercises

Write a program Initials.java thatprints your initials using nine rows of asterisks like the one below.
Describe what happens if, in HelloWorld.java, you omit
1. main
2. String
3. HelloWorld
4. System.out
5. println
Describe what happens if, in HelloWorld.java, you omit
1. the ;
2. the first '
3. the second '
4. the first {
5. the second {
6. the first }
7. the second }
Describe what happens if, in HelloWorld.java,you misspell (by, say, omitting the second letter)
1. main
2. String
3. HelloWorld
4. System.out
5. println
I typed in the following program. It compiles fine, but when I executeit, I get the error java.lang.NoSuchMethodError: main.What am I doing wrong?Answer: you forgot the String[] args. It isrequired.

Last modified on August 02, 2016.
Copyright © 2000–2019Robert SedgewickandKevin Wayne.All rights reserved.

This page describes how to install and uninstall JDK 8 for OS X computers.

This page has these topics:

See 'JDK 8 and JRE 8 Installation Start Here' for general information about installing JDK 8 and JRE 8.

See 'OS X Platform Install FAQ' for general information about installing JDK 8 on OS X.

System Requirements

Observe the following requirements:

Any Intel-based computer running OS X 10.8 (Mountain Lion) or later.
Administrator privileges.

Note that installing the JDK on OS X is performed on a system wide basis, for all users, and administrator privileges are required. You cannot install Java for a single user.

Installing the JDK also installs the JRE. The one exception is that the system will not replace the current JRE with a lower version. To install a lower version of the JRE, first uninstall the current version as described in 'Uninstalling the JRE'.

JDK Installation Instructions

When you install the Java Development Kit (JDK), the associated Java Runtime Environment (JRE) is installed at the same time. The JavaFX SDK and Runtime are also installed and integrated into the standard JDK directory structure.

Depending on your processor, the downloaded file has one of the following names:

jdk-8uversion-macosx-amd64.dmg
jdk-8uversion-macosx-x64.dmg

Where version is 6 or later.

Download the file.
Before the file can be downloaded, you must accept the license agreement.
From either the Downloads window of the browser, or from the file browser, double click the .dmg file to launch it.
A Finder window appears containing an icon of an open box and the name of the .pkg file.

Double click the package icon to launch the Install app.

The Install app displays the Introduction window.

Note:

In some cases, a Destination Select window appears. This is a bug, as there is only one option available. If you see this window, select Install for all users of this computer to enable the Continue button.

Click Continue.
The Installation Type window appears.
Click Install.
A window appears that says 'Installer is trying to install new software. Type your password to allow this.'
Enter the Administrator login and password and click Install Software.
The software is installed and a confirmation window appears.
Refer to http://www.oracle.com/technetwork/java/javase/downloads/jdk-for-mac-readme-1564562.html for more information about the installation.
After the software is installed, delete the .dmg file if you want to save disk space.

Determining the Default Version of the JDK

If you have not yet installed Apple's Java OS X 2012-006 update, then you are still using a version of Apple Java 6 that includes the plug-in and the Java Preferences app. See 'Note for Users of OS X that Include Apple Java 6 Plug-in'.

There can be multiple JDKs installed on a system, as many as you wish.

When launching a Java application through the command line, the system uses the default JDK. It is possible for the version of the JRE to be different than the version of the JDK.

You can determine which version of the JDK is the default by typing java -version in a Terminal window. If the installed version is 8u6, you will see a string that includes the text 1.8.0_06. For example:

To run a different version of Java, either specify the full path, or use the java_home tool:

For more information, see the java_home(1) man page.