Java/FAQ

Java FAQ

Questions about the Java environment running on Fedora.

General

What is the Java environment in Fedora?

OpenJDK is the default Java environment since Fedora 17. It is Oracle(formerly Sun) Java under a free and open source license, and there are runtime and development packages.

I didn't get Java at install time, but I want to install it now. How do I do that?

The OpenJDK runtime and development packages are installed by default during any large-media install, such as from the Fedora DVD.

If installing from a live image, such as a live CD or USB flash drive, add the OpenJDK 7 runtime after the install:

• Use the software center and use search to find the package(s) to install.

• To install from the command line:

su -c "dnf install java-1.?.0-openjdk"

This package contains just the Java Runtime Environment. To develop Java programs, install the java-1.?.0-openjdk-devel package. Install all the OpenJDK packages, including the API documentation, by using the wildcard java-1.?.0-openjdk*.

Refer to the Software Management Guide for more information.

Fedora's Java environment does not provide the functionality I require. Can I install another?

The JPackage Project has packages for a variety of Java environments, both free and proprietary. These packages are designed so that more than one may be installed simultaneously. The Java environment in Fedora is fully compatible with this system.

Installing a JPackage Java environment is described in detail in JpackageJava .

Java environments other than from JPackage are likely to interfere with Fedora's Java environment and their use is not recommended.

Usage

Where is everything?

Java packages in Fedora are in the main based on and compatible with those of the JPackage Project . Their packaging infrastructure and policy documentation is included in full in the jpackage-utils package. The main things you probably want to know, however, are that the commands (java, javac, jar, etc) are on the system path, the main jar repository is /usr/share/java and the extensions jar repository is /usr/share/java-ext

What about running Java applets in the browser?

su -c "dnf install icedtea-web"

How can I assist the development of OpenJDK

Hack on the JDK itself, right here in the growing OpenJDK Community: Browse the code on the web, get a source bundle or clone a Mercurial repository to make a local copy, learn how to build and hack on the code with the NetBeans IDE, and contribute a patch to fix a bug, enhance an existing component, or define a new feature.

How do I get stack traces from Java programs when filing a bug report?

See JavaStackTraces

Why are my executable JAR files opened instead of being executed?

The default action for .jar files is to treat them as ordinary .zip files. Two ways to fix this:

• Register a binfmt for .jar (see /usr/share/doc/kernel-doc-*/Documentation/java.txt for details)

• Change the default action in nautilus, or whatever file manager you use. In nautilus, I think you can do this by: right-click on the .jar file, choose Properties, choose Open With, click Add, click Use a custom command, and type in xterm -e java -jar

Can I run Oracle Java on Fedora?

You sure can, however, we recommend you to try OpenJDK first and switch to Oracle Java only if you experience problems with the OpenJDK.

Oracle Java can be downloaded from here as an RPM package. You can use afterwards the alternatives program to toggle between different Java runtime environments, compilers, etc.

See Also

• Java