Java
"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
Arch Linux officially supports the open source OpenJDK versions 7 and 8. All these JVM can be installed without conflict and switched between using helper script archlinux-java
. Several other Java environments are available in AUR but are not officially supported.
Contents
Installation
The following packages are available in the official repositories:
OpenJDK 7:
Package name | Use |
---|---|
jre7-openjdk-headless | Java runtime environment (JRE) without any graphical tool - version 7 |
jre7-openjdk | Complete Java Runtime Environment (JRE) - version 7 |
jdk7-openjdk | Java Development Kit (JDK) - version 7 |
openjdk7-doc | OpenJDK javadoc - version 7 |
openjdk7-src | OpenJDK sources - version 7 |
OpenJDK 8:
Package name | Use |
---|---|
jre8-openjdk-headless | Java runtime environment (JRE) without any graphical tool - version 8 |
jre8-openjdk | Complete Java Runtime Environment (JRE) - version 8 |
jdk8-openjdk | Java Development Kit (JDK) - version 8 |
openjdk8-doc | OpenJDK javadoc - version 8 |
openjdk8-src | OpenJDK sources - version 8 |
$PATH
variable). This can be done by sourcing /etc/profile
from the command line or by logging out/in again of a Desktop Environment.Two common packages named java-runtime-common and java-environment-common are automatically pulled as dependency and provide environment file /etc/profile.d/jre.sh
. This file contains all JVM common environment variables. Package java-runtime-common also provides a utility script archlinux-java
that can display and change the default Java environment. This script sets links /usr/lib/jvm/default
and /usr/lib/jvm/default-runtime
to point at a valid non-conflicting Java environment installed and Java runtime in /var/lib/jvm/java-${JAVA_MAJOR_VERSION}-${VENDOR_NAME
}. Most executable provided by the Java environment set have direct links from /usr/bin
, others are available in $PATH
.
/etc/profile.d/jdk.sh
is not provided anymore by any package.Flagging packages as out-of-date
Although the Arch Linux package releases may contain a reference to the proprietary versions the packages base on, the open-source project has its own versioning:
- jre7-openjdk, jdk7-openjdk and jre7-openjdk-headless and their OpenJDK 8 couterparts should be flagged as out-of-date based on the IcedTea version (e.g.
2.4.3
), rather than on the Oracle reference version (e.g.u45
in the release7.u45_2.4.3-1
). - icedtea-web should be flagged as out-of-date based on the IcedTea Web version (e.g.
1.4.1
). This is independent of the IcedTea version.
Switching between JVM
Helper script archlinux-java
provides such functionalities:
archlinux-java <COMMAND> COMMAND: status List installed Java environments and enabled one get Return the short name of the Java environment set as default set <JAVA_ENV> Force <JAVA_ENV> as default unset Unset current default Java environment fix Fix an invalid/broken default Java environment configuration
List compatible Java environments installed
% archlinux-java status
Example:
% archlinux-java status Available Java environments: java-7-openjdk (default) java-8-openjdk/jre
Note the (default) denoting that java-7-openjdk
is currently set as default. Invocation of java
and other binaries will rely on this Java install. Also note on the previous output that only the JRE part of OpenJDK 8 is installed here.
Change default Java environment
# archlinux-java set <JAVA_ENV_NAME>
Example:
# archlinux-java set java-8-openjdk/jre
Note that archlinux-java
will not let you set an invalid Java environment. In the previous example, jre7-openjdk is installed but jdk8-openjdk is not so trying to set java-8-openjdk
will fail:
# archlinux-java set java-8-openjdk '/usr/lib/jvm/java-8-openjdk' is not a valid Java environment path
Unsetting the default Java environment
There should be no need to unset a Java environment as packages providing them should take care of this. Still should you want to do so, just use command unset
:
# archlinux-java unset
Fixing the default Java environment
If /usr/bin
links are incorrect or if an invalid Java environment link is set, calling the archlinux-java fix
command tries to fix these. Also note that if no default Java environment is set, this will look for valid ones and try to set it for you. Officially supported packages "OpenJDK 7" and "OpenJDK 8" will be considered first in this order, then un-official packages from AUR.
# archlinux-java fix
Former "One time setup" trick
Formerly, package java-common could be forced into using a Java installation by setting environment variable JAVA_HOME
. This cannot be done anymore with latest version of java-runtime-common.
Package pre-requisites to support archlinux-java
This section is targeted at packager willing to provide packages in AUR for an alternate JVM and be able to integrate with Arch Linux JVM scheme to use archlinux-java
. To do so, packages should:
- Place all files under
/usr/lib/jvm/java-${JAVA_MAJOR_VERSION}-${VENDOR_NAME}
- Ensure all executables for which java-runtime-common and java-environment-common provide links are available in the corresponding package
- Ship links from
/usr/bin
to executables, only if these links do not already belong to java-runtime-common and java-environment-common - Suffix man pages with
-${VENDOR_NAME}${JAVA_MAJOR_VERSION}
to prevent conflicts (see jre8-openjdk file list where man pages are suffixed with-openjdk8
) - Do not declare any conflicts nor replaces with other JDKs,
java-runtime
,java-runtime-headless
norjava-environment
- Use script
archlinux-java
in install functions to set the Java environment as default if no other valid Java environment is already set (ie: package should not force install as default). See officially supported Java environment package sources for examples
Also please note that:
- Packages that need any Java environment should declare dependency on
java-runtime
,java-runtime-headless
orjava-environment
as usual - Packages that need a specific Java vendor should declare dependency on the corresponding package
- OpenJDK packages now declare
provides="java-runtime-openjdk=${pkgver}"
etc. This enables a third-party package to declare dependency on an OpenJDK without specifying a version
Unsupported JVM from AUR
archlinux-java
Java SE
Several packages from AUR provide Oracle's implementations of JRE and JDK, but the main ones are jreAUR and jdkAUR.
Java SE 6/7
Older versions include jre6AUR/jre6-compatAUR/jre7AUR/jre7-oracleAUR and jdk6AUR/jdk6-compatAUR/jdk7AUR/jdk7-oracleAUR.
Oracle JRockit
JRockit is Oracle's JIT version of Java, available as jrockitAUR.
VMkit
VMkit is an LLVM-based framework for JIT virtual machines. J3 is a JVM running on VMkit. The webpage can be found here: vmkit. J3 depends on the GNU classpath libraries, but may also work with the Apache class path libraries.
Parrot VM
Parrot is a VM that 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. parrot is available in the official repositories and parrot-gitAUR in the AUR.
Troubleshooting
MySQL
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 the instructions in MySQL#Grant Remote Access.
Impersonate another window manager
You may use the wmname from suckless.org to make the JVM believe you are running a different window manager. This may solve a rendering issue of Java GUIs occurring in window managers like Awesome or Dwm.
$ 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, some users prefer to impersonate LG3D
, the non-re-parenting window manager written by Sun, in Java.
Illegible fonts
In addition to the suggestions mentioned below in #Better font rendering, some fonts may still not be legible afterwards. If this is the case, there is a good chance Microsoft fonts are being used. Install ttf-ms-fontsAUR from the AUR.
Missing text in some applications
If some applications are completely missing texts it may help to use the options under #Tips and tricks as suggested in FS#40871.
Too many levels of symbolic links
If you get an error like:
/usr/bin/java: line 2: /usr/lib/jvm/default/bin/java: Too many levels of symbolic links /usr/bin/java: line 2: exec: /usr/lib/jvm/default/bin/java: cannot execute: Too many levels of symbolic links
#Fixing the default Java environment should solve the problem. See also [1].
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 ~/.bashrc
(or /etc/profile.d/jre.sh
to affect programs that are not run by sourcing ~/.bashrc
, e.g., launching a program from Gnome's Applications view):
export _JAVA_OPTIONS="-D<option 1> -D<option 2>..."
For example, to use system anti-aliased fonts and make swing use the GTK look and feel:
export _JAVA_OPTIONS='-Dawt.useSystemAAFontSettings=on -Dswing.aatext=true -Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel'
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: awt.useSystemAAFontSettings=on
, swing.aatext=true
See Java Runtime Environment Fonts for more detailed information.
GTK LookAndFeel
If your Java programs look ugly, you may want to set up the default look and feel for the swing components: swing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel
.
Some stubborn Java programs insist on using the cross platform Metal look and feel. In some of these cases you can force these apps to use the GTK look and feel by setting the following property:
swing.crossplatformlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel
.