Set up Java on your system

Set up Java on your system

The Java platform is distributed as the Java Runtime Environment (JRE), which contains the JVM, a browser plugin for running applets, the standard class library, and a few other items. You will need both the JRE and a JDK in order to develop and run Java programs. The JDK download from Oracle includes the JRE and the basic development tools required to begin developing, debugging, and monitoring your applications in Java. At the time of this writing the most current version of the JDK is Java SE 8u45.

Platform compatibility

The JDK is available for 32-bit/64-bit Linux, 64-bit Mac OS X, 64-bit Solaris SPARC, 64-bit Solaris, and 32-bit/64-bit Windows platforms.

After downloading and installing the JDK you should update your PATH environment variable to reference the JDK's bin subdirectory of the installation directory, so that you can execute JDK tools from any directory in the file system. If you need instructions for updating PATH you can find them here. (Note that my examples are based on using the command line with command-line Java tools, but you can just as easily use Net Beans or another IDE if you prefer.)

Directory tip!

Pointing your JAVA_HOME environment variable to the JDK's installation directory enables any external Java-dependent software that you might subsequently install to locate your JDK installation.

The JDK installation directory contains various files and sub directories, including the following three important sub directories:

bin contains various JDK tools, such as the Java compiler (javac) and Java application launcher (java). You'll interact with these and other tools throughout the Java 101 series. (Note that the Java compiler and the JIT compiler are two different compilers.)

jre contains the JDK's private copy of the JRE, which lets you run Java programs without having to download and install the standalone JRE.

lib contains library files that are used by JDK tools. For example, tools.jar contains the Java compiler's class files -- the compiler is a Java application. (The javac tool isn't the compiler, but is a native-platform-specific convenience for starting the JVM and running the Java-based compiler.)

Now that you've installed the JDK and configured your development environment, you are ready to code your first Java application.