Introduction to this FAQ

This FAQ was started by Javier Fernández-Sanguino who on February 1st, 2000 was enough to send a message to the debian-java mailing list with the subject "How about a Debian-Java-FAQ?". Of course, since "every idea is a responsibility" he had to do this himself looking through the three month-long archive of the newborn mailing list.

The purpose of this FAQ is to be a place to look for all kinds of questions a developer or user might have regarding Java as far as Debian is concerned. It includes license issues, development packages available, and programs related to building a Free Software Java environment.

Thanks go to all the (many) contributors from the debian-java mailing list, who have made this document possible. Without their knowledge this FAQ would not be at all possible since I only have a vague knowledge of what they're talking about when I browse the list.

Special thanks go to Paul Reavis, whose previous Debian-JDK informational page I used to add more information, and who made useful suggestions to this document. Also to Peter Moulder who revised thoroughly the FAQ and provided many suggestions, to Juergen Kreileder, maintainer of Blackdown's debian packages who pointed out some mistakes, and to Egon Willighagen, who has provided quite a lot of proper patches to update its content.

This document does not address issues with other Linux distributions, or with non-Debian-specific problems. Location of this FAQ

This FAQ is published under the Debian Documentation Project at . The java-common (available at ) provides an HTML version for offline reading. The package version does not provide Text and PDF versions currently (if you want them please submit a bug 'wishlist' to the package). Also, the web version might be more up-to-date than the package's offline version. Sending bugs on this FAQ

Please note that this FAQ is still outdated but gets updated step by step.

Please file bug reports against the java-common package if you find errors or have suggestions on how to improve this document. However, make sure you have read the latest online version of the english text available at before filing a bug report. Translations, if available, and the offline version in the java-common package might be out of date. What is Java?

Java is a programming language originally developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle Corporation) and released in 1995 as a core component of Sun Microsystems' Java platform. Since May 2007, Sun/Oracle with some partners like Red Hat provide a free implementation released under the GNU GPL called OpenJDK. More information can be found at . Where can I ask questions about Java on Debian?

The appropriate place to ask such questions is debian-java at lists.debian.org. You can subscribe at the page. Complementary information

Users might want to access some online sources to complement the information available in this FAQ which might be, sometimes, too out of date. The main source of information is the at the Debian's wiki.

Since Ubuntu is based on Debian, some users might find it helpful to check the tips on on Ubuntu's wiki. Uncovered issues

This FAQ does not describe some issues due to lack of time and/or information. If you are able to help in any of these, please, provide them to the documentation maintainer: Information on how to setup a fully working Servlet engine (Application Server) using Apache and Tomcat or information on how to setup non-free application servers (such as WebSphere) in Debian. Specific information targeted for non-i386 users (PowerPC users and AMD64 users), some can be found in Ubuntu's wiki. Java Development

What full-fledged Java development platforms are available in Debian?

If you are looking for an integrated, java virtual machine, compiler and runtime environment Debian does provide them. Of course that would depend on the Debian GNU/Linux version you are using, generally speaking they would be: The deprecated Kaffe in Debian 5.0 Lenny. The deprecated Sun Java 5 jdk, available in the Debian 5.0 Lenny release in the non-free component. Sun's Java 6 jdk, available in Debian Lenny and Debian Squeeze, also as packages in the non-free component. Sun's OpenJDK 6, available since the Debian 5.0 Lenny release in the main section. The combination GCJ, GIJ, and Classpath in the main section.

It is recommended to install one of the default-jdk or default-jre meta packages which either installs OpenJDK or GCJ depending on the architecture and Debian version. What free platforms are there and how can I contribute?

Please help one of the Free Java implementations if you want to use Java in Debian. There are a lot of projects that you can choose from: openjdk: gcj and libgcj: FastJar , as a jar tool. Classpath . Most of the Standard classes for Java 1.2 (except Swing and RMI) are implemented by the ClassPath project, it tries to build an alternative to jdk's 1.2 core classes. (NB: This was removed from Squeeze) Mauve is a free suite to test if these tools are 'compliant'.

Most free Java development is grouped under the . Questions on platforms and license concerns Java 5 and 6

There are binary packages available for the Java 5 and Java 6 platforms since the Debian 5.0 ('lenny') release. These packages are available in the non-free section, so you have to configure your apt sources appropriately. If you have the following in your /etc/apt/sources.list: deb http://ftp.debian.org/debian lenny main you need to change it to: deb http://ftp.debian.org/debian lenny main contrib non-free Once this is done and you have updated your package database. You can either install the Java development kit: apt-get install sun-java6-jdk or the Java runtime environment: apt-get install sun-java6-jre

Similarly, you can install the Java 5 development kit: apt-get install sun-java5-jdk or the Java 5 runtime environment: apt-get install sun-java5-jre

You might want to update the alternatives system to have Sun's tools as the default: update-java-alternatives -s java-6-sun Or for java 5: update-java-alternatives -s java-1.5.0-sun Sun's OpenJDK

Sun adopted in november 2006 the GPL license for almost all of the virtual machine and GPL v2 + the Classpath exceptionThis is similar to GCC linking exception in that it allows non-GPL code to be linked with the GPL code. This exception was developed by the for the class libraries and those parts of the virtual machine that expose public APIs.

As a consequence, the free OpenJDK code is available in Debian since the 5.0 (lenny) release.

You can install the Java development kit: apt-get install openjdk-6-jdk or the Java runtime environment: apt-get install openjdk-6-jre

For more information see . Making Debian packages for Java programs. Can the package go into main?

Yes, but only if it can be build and run with Java programs/tools in main, and if it has a Debian compliant open source license. If it needs programs from contrib or non-free, then is must go into contrib or non-free, depending on the license of the program itself. Is there a good example Debian package?

There are many Debian packages of both Java applications and libraries. These may serve as an good starting point, as it can serve as an example for making a new Debian package.

A good start would be to check out the pkg-java project on Alioth: .

Note that there are many ways to make a Debian package, making use of Ant or Makefiles does not really matter. But, some tips for good practice are given on the pkg-java page: and . What tools are available to make maintaining a Java packages easier?

Both cdbs and debhelper (dh7) have support for ant scripts. There are also a number of specialized tools or build helpers. Have a look at javahelper or maven-debian-helper. gcj-jdk also has a dh_javadoc tool.