JavaHighHow to update java on mac
  1. It is likely that most Mac users do not have Java, as it does not come pre-installed for you with OS X as it once did. Since OS X Lion arrived a year ago, installing Java on a Mac has been a manual opt-in process. It is also likely that besides a few web sites and an occasional piece of software you may want to run, you don’t really need Java.
  2. Learning Java is one of the smartest things you can do at the moment. The world's most popular programming language is easy to set up and install on a Mac, and there are plenty of resources to.
  3. 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 running Mac 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.

Java however, is a plugin for web browsers. That means it is an extra bit of software that can be optionally loaded into a web browser to give it new features or functionality. That is what this page is about. Do I need Java installed? Years ago, Java was the first and very popular way of adding complex interactivity to websites. It says, “To use the java command-line tool, you need to install a JDK.” It asks you to click “More Info” and visit the JDK (Java Developer Kit) download website. The reason you’re receiving this message is due to the removal of Java support in newer versions of OS X for security reasons.

Hello, World in Java on Mac OS X


This documents instructs you on how to setup a Java programmingenvironment for your Mac OS X computer and provides a step-by-stepguide to creating, compiling, and executing a Java program.We assume you are running at least OS X 10.2.3.All of the software is freely available on the Web.

What Do I Need Java For On Mac
Java

You will use the Java compiler javac to compile your Java programs andthe Java interpreter java to run them.Mac OS X includes implementation of Java 2 Standard Edition (J2SE) 1.4.1,so there is nothing to do in this step.

Command line interface

You will type commands in an application called the Terminal.You might enjoy reading Neal Stephenson's light-heartedessay In the Beginningwas the Command Line.

  • Open a terminal window. You can find this underGo -> Applications -> Utilities. Drag the Terminal to your dock sinceyou will be using it frequently.
  • You should now have a Terminal window somewhere on the screen.It will have a command prompt that looks something like:
  • To check that you have the right version of Java installed, typethe text in boldface below.
    If Java is installed, you should see something like:
    Now, check that the Java compiler is accessible.
    If it is installed, you should see something like
    If not, install the Developers Tools CD that came with your Mac anduse Software Update to make sure you have the latest version.
  • Now, create a directory to store your Java programs.In the window containing the Command Prompt, type the bold commandsbelow:
    The mkdir command creates a new directory;the cd command changes the current working directory.After executing these commands, your working directoryis the newly created ~username/introcs/hello/. All of yourfiles for Assignment 0 will go here.Don't be scared by the Terminal - you will only need to use afew basic commands. Keep this window open since you will need it laterin the assignment.
  • Since you will be using the Terminal frequently, we recommend customizingWe recommend customizing the default settings....

Text Editor

You will type and edit your programs in a text editor called JEdit.JEdit is similar to conventional word processors like MS Word,but it features many specialized programming tools includingsyntax highlighting, bracket matching, auto indenting, indentshifting, line numbering, and commenting out code. It's even written in Java.

  • Downloadthe latest stable version of JEdit using the MacOSX package link.
  • We recommend the following JEdit customizations.
    • Enable Mac OS style menubar inUtilities -> Global Options -> Plugins -> Mac OS Settings
    • Change the default indentation to four spaces viaUtilities -> Global Options -> Editing -> Indent Width andUtilities -> Global Options -> Editing -> Tab Width. Global Options -> Editing -> Soft tabs.-->
    • Change the default tab width when printing to four spaces viaUtilities -> Global Options -> Printing -> Tab width when printing
    • Add line numbers by checking Utilities -> Global Options -> Gutter -> Line Numbering
    • Allow at most 80 characters per line byUtilities -> Global Options -> Editing -> Word wrap -> hard andUtilities -> Global Options -> Editing -> Wrap margin -> 80.
    • Change the default line separator to Unix viaUtilities -> Global Options -> Loading & Saving -> Default Line Separator
    • Remove the annoying . that marks the end of a line by uncheckingUtilities -> Global Options -> Text Area -> End of Line Markers
  • To associate .java files with JEdit so that when you double-click a .java file,it opens it in JEdit:
    • Right click a .java file (or click then shift-right click it if using Windows NT)
    • Choose Open With...
    • Select JEdit from the list of programs or locate JEdit by selecting Otherif necessary.
    • Check the Always use this program to open this file type box
Apple purists may prefer Project Builder which can be found in the Findervia Computer -> OS X Partition -> Developer -> Applications -> Project Builder.
Create the program

Now you are ready to write your first Java program.

  • Launch JEdit Start -> jEdit.
  • In the JEdit window, type the Java program exactly as it appears below.If you omit even a semicolon, the program won't work.
  • When you're done, save the program usingFile -> Save As, chose the directory C:introcshelloand type in the file name HelloWorld.java.The file name is case sensitive and must exactly match the name of the classin the Java program. Don't forget to include the .java extension in thefile name.
Compile the program

It is now time to convert your Java program into a form more amenable for executingon a computer.

  • From the Command Prompt, type
    If javac complains in some way, you mistyped something, and you should check your program carefully. Ask for help if you can't see the mistake.
  • If everything went well, you should see the followingin the Command Prompt:
    Silence is golden in computer science.

How To Install Java On Mac

Execute the program

Run Java On Mac

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

  • At the Command Prompt, type
  • If all goes well, you should see
  • You may need to repeat this edit-compile-execute cycle a few times before it all goes smoothly.Use the up and down arrow keys to repeat previous commands and avoid extra typing.
Congratulations, you are now a Java programmer!
Troubleshooting

When I try to run java I get: Exception in thread 'main'java.lang.NoClassDefFoundErrorYour CLASSPATH may have been set by some other program so that it no longer includes the current working directory in the search path. Try running your program with the command line