Difference between revisions of "Java"
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Revision as of 12:00, 24 May 2012
|Summary help replacing me|
|This article explains how to install and configure JRE/JDK.|
|Java Package Guidelines|
"Java is a programming language originally developed by Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of computer architecture." — Wikipedia article
- 1 Installation
- 2 Troubleshooting
- 3 Tips and tricks
The only JVM implementation in supported repositories is the open source OpenJDK. Additional Java implementations are available via the AUR. Keep in mind that the open-source and closed-source versions cannot be installed simultaneously. The open-source version is nearly perfect at the time of writing, and there is mostly no need anymore to install Oracle's proprietary version of Java.
To be able to run Java programs, you can install Java runtime with the package , available in the official repositories. There is also a Java Development Kit in . For those interested in the old Java v6, both JRE6 and JDK6 can be found in .
Prior to the retirement of the Oracle DLJ, it was possible to simply install the
jdk packages from the repositories. However, now Arch Linux (and any other GNU/Linux distribution) can no longer package the Oracle implementation of Java. The OpenJDK packages are the recommended providers of
AUR contains packages forAUR and AUR, the Oracle implementations of Java.
Oracle JVM (Java 6)
Seeing as how Java SE 6 for instructions on how to do so manually.AUR and AUR have been updated to Java SE 7, the installation of Java SE 6, the older reference implementation of Java can't be installed through the AUR. However, it can be installed manually. To do so, consult the article
Apache Harmony is a clean room re-implementation of the Java language and comes under the Free Apache license. A binary re-distribution of the Harmony JRE can be found in the AUR: AUR.
Kaffe is another clean-room implementation of a Java VM without official endorsement from Sun/Oracle. A git package of Kaffe can be found in the AUR here: AUR. The Kaffe VM is redistributed according to the GPL license.
BEA JRockit JIT JVM (+JDK)
JRockit is JIT version of Java, provided by Oracle and available from the AUR here: AUR.
VMkit LLVM-based JIT VM
VMkit is an LLVM-based framework for JIT virtual machines. J3 is a JVM running on VMkit. A broken build for VMkit can be found in the AUR here: AUR. J3 depends on the GNU classpath libraries, but may also work with the Apache class path libraries.
The Parrot VM offers experimental support for Java through two different methods: Either as a Java VM bytecode translator or as a Java compiler targeting the Parrot VM. Available in the AUR package AUR.
Due to the fact that the JDBC-drivers often use the port in the URL to establish a connection to the database, it is considered "remote" (i.e., MySQL does not listen to the port as per its default settings) despite the fact that they are possibly running on the same host, Thus, to use JDBC and MySQL you should enable remote access to MySQL, following instructions in MySQL article.
Java sound with Pulseaudio
By default, Java and Pulseaudio do not get along very well with each other, but this is easy to fix using padsp.
(These paths are correct for Sun's Java, you will need to change the paths for OpenJDK)
First, rename the
java binary to
# mv /opt/java/jre/bin/java /opt/java/jre/bin/java.bin
Then, create a new launcher script at
#!/bin/sh padsp /opt/java/jre/bin/java.bin "$@"
Finally, make the launcher script executable
# chmod +x /opt/java/jre/bin/java
You will need to redo this process on each update of Java.
You can also try replacing padsp with aoss, which can also fix it under standard ALSA as well as in Pulse, do what works best. I must warn everyone that these hacks sometimes work perfect, but are sometimes very unstable as well.
Impersonate Another Window Manager
$ wmname LG3D
(You must restart the application in question after issuing the wmname command.)
This works because the JVM contains a hard-coded list of known non-re-parenting window managers. For maximum irony, many users prefer to impersonate “
LG3D,” the non-re-parenting window manager written by Sun, in Java.
Tips and tricks
Behavior of most Java applications can be controlled by supplying predefined variables to Java runtime. From this forum post, a way to do it consists of adding the following line in your
/etc/profile.d/jre.sh to affect all users):
export _JAVA_OPTIONS="-D<option 1> -D<option 2>..."
Better font rendering
Both closed source and open source implementations of Java are known to have improperly implemented anti-aliasing of fonts. This can be fixed with the following options:
If your Java programs look ugly, you may want to set up the default look and feel for the swing components: