Java and the Mac OS X Terminal
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How to install Java JDK Java Development Kit on mac. In Mac OSX 10.5 or later, Apple recommends to set the $JAVAHOME variable to /usr/libexec/javahome, jus. Since macOS is based on Unix there are a number of ways to compress files and folders within the filing system using Unix based application code, below are a few options using the Terminal or command line interface (cli). When you start a Java application by clicking a JNLP file, or through the browser, it uses the installed JRE. Only one JRE can be installed. See Determining the JRE Version Installed on macOS. When you run a Java application from the command line, it uses the default JDK.
This document instructs you on how to use the Mac OS X Terminal with Java.
You will use the Java compiler javac to compile your Java programs andthe Java interpreter java to run them.To verify that Apple's implementation of Java 2 Standard Edition (Java SE 6) isalready installed:
- Run Software Update.
- Run Applications/Utilities/Java/Java Preferencesand verify that the Java SE 6 - 64-bit entry is checked andfirst in the list; if not, drag to change the preferred order.
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You will type commands in an application called the Terminal.
- 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 prompt that looks something like:
- To check that you are running the right version of Java, typethe commands in boldface below. You should see something similar to the information printed below. The importantpart is that it says 1.6 or 1.5 (and not 1.4).
Then type
- Since you will be using the Terminal frequently, you may want tocustomize the default window settings (e.g., Monaco 13pt font with antialiasing).
- To check that you are running the right version of Java, typethe commands in boldface below. You should see something similar to the information printed below. The importantpart is that it says 1.6 or 1.5 (and not 1.4).
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You will use the javac command to convert your Java program into a form moreamenable for execution on a computer.
- From the Terminal, navigate to the directory containing your .javafiles, say ~wayne/introcs/hello, by typing the cd commandbelow.
- Assuming the file, say HelloWorld.java is in the currentworking directory, type the javac command below to compile it.
If everything went well, you should see no error messages.
- Assuming the file, say HelloWorld.java is in the currentworking directory, type the javac command below to compile it.
You will use the java command to execute your program.
Install Java On Mac Terminal
- From the Terminal, type the java command below.If all goes well, you should see the output of the program -Hello, World.
Input and Output |
If your program gets stuck in an infinite loop, type Ctrl-c to break out.
Java Terminal Commands
If you are entering input from the keyboard, you can signifyto your program that there is no more data by typingCtrl-d for EOF (end of file).You should type this character on its own line.
Run Java File From Terminal
When I try to run java I get: Exception in thread 'main' java.lang.NoClassDefFoundError.First, be sure that HelloWorld.class is in the current directory.Be sure to type java HelloWorld without a trailing .classor .java.If this was not your problem, it's possiblethat your CLASSPATH was set by some other program so that it no longerincludes the current working directory.Try running your program with the command line
If this works, your classpath is set incorrectly.I get the error 'class file has wrong version 50.0, should be 49.0' when I compilefrom the Terminal. What does this mean?It's probably because DrJava is configured to use Java 6.0 and and your Terminal is configured to use Java 5.0.To change the default version of Java in your Terminal, launchJava Preferencest. Drag the Java SE 6 - 64-bit entryto appear first.
How do I get the menu to display at the topof the screen instead of at the top of the frame?Execute with java -Dapple.laf.useScreenMenuBar=true
Where can I learn more about the command line?Here is a short tutorial on thecommand-line.
Online Java Terminal
The following are the system requirements for installing the JDK and the JRE on macOS:
- Any Intel-based computer running macOS.
- Administrator privileges.You cannot install Java for a single user. Installing the JDK and JRE on macOS is performed on a systemwide basis for all users. Administrator privileges are required to install the JDK and JRE on macOS.
- When you install the JDK, it also installs the JRE. However, the system will not replace the current JRE with a lower version.To determine the current JRE version installed on your system, see Determining the JRE Version Installed on macOS. To install an earlier version of the JRE, you must first uninstall the current version. See Uninstalling the JRE on macOS.
- When you install the JRE, you can install only one JRE on your system at a time. The system will not install a JRE that has an earlier version than the current version.To determine the current JRE version installed on your system, see Determining the JRE Version Installed on macOS. To install an earlier version of the JRE, you must first uninstall the current version. See Uninstalling the JRE on macOS.Note:Installing a JRE from Oracle will not update
java -version
symlinks or addjava
to your path. To do this, you must install the JDK.