Difference between revisions of "Java"

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[[Category:Programming language]]
 
[[Category:Programming language]]
 
[[cs:Java]]
 
[[cs:Java]]
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[[de:Java]]
 
[[es:Java]]
 
[[es:Java]]
 
[[fr:Java]]
 
[[fr:Java]]
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[[ru:Java]]
 
[[ru:Java]]
 
[[tr:Java]]
 
[[tr:Java]]
{{Article summary start}}
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{{Related articles start}}
{{Article summary text|This article explains how to install and configure JRE/JDK.}}
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{{Related|Java Package Guidelines}}
{{Article summary heading|Related}}
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{{Related articles end}}
{{Article summary wiki|Java Package Guidelines}}
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{{Article summary end}}
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"''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:Java (programming language)|Wikipedia article]]
 
"''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:Java (programming language)|Wikipedia article]]
  
 
== Installation ==
 
== Installation ==
 
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The only supported JVM implementation in Arch Linux is the open source [http://openjdk.java.net/ OpenJDK]. It is nearly perfect, and it should not be necessary to install Oracle's proprietary version of Java. If you want to install Oracle Java alongside OpenJDK, see [[#JDK-compat]].
The only JVM implementation in supported repositories is the open source [http://openjdk.java.net/ 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.
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{{Note|After installation, the Java environment will need recognized by the shell ({{Ic|$PATH}} variable and {{Ic|$JAVA_HOME}}).  This can be done from the command line by sourcing {{Ic|/etc/profile}}, and for Desktop Environments it is likely a logout/login will be necessary.}}
 
{{Note|After installation, the Java environment will need recognized by the shell ({{Ic|$PATH}} variable and {{Ic|$JAVA_HOME}}).  This can be done from the command line by sourcing {{Ic|/etc/profile}}, and for Desktop Environments it is likely a logout/login will be necessary.}}
  
=== OpenJDK JVM ===
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=== OpenJDK ===
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The OpenJDK Java runtime environment (''JRE'') can be installed with the package {{Pkg|jre7-openjdk}}, available in the [[official repositories]]. There is also a Java development kit (''JDK'') available with the package {{Pkg|jdk7-openjdk}}.
  
To be able to run Java programs, you can install [[Wikipedia:JRE|Java runtime]] with the package {{Pkg|jre7-openjdk}}, available in the [[official repositories]]. There is also a [[Wikipedia:JDK|Java Development Kit]] in {{Pkg|jdk7-openjdk}}. For those interested in the old Java v6, both JRE6 and JDK6 can be found in {{Pkg|openjdk6}}.
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If you want Java functionality in browsers ([[Wikipedia:Java applet|Java applets]] and [[Wikipedia:Java Web Start|Java Web Start]]), install {{Pkg|icedtea-web-java7}}. For more details see [[Browser Plugins#Java (IcedTea)]].
  
You will likely need the {{Pkg|icedtea-web-java7}} package for Java functionality in browsers, namely [[Wikipedia:Java applet|applets]] and [[Wikipedia:Java Web Start|Web Start]] (for more details see [[Browser Plugins#Java (IcedTea)]]).
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==== Flagging packages as out-of-date ====
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*{{Pkg|jre7-openjdk}}, {{Pkg|jdk7-openjdk}} and {{Pkg|jre7-openjdk-headless}} should be flagged as out-of-date based on the [http://icedtea.wildebeest.org/download/source ''IcedTea'' version] (e.g. {{ic|2.4.3}}), rather than on their Oracle version (e.g. {{ic|u45}}).
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*{{Pkg|icedtea-web-java7}} should be flagged as out-of-date based on the [http://icedtea.wildebeest.org/download/source ''IcedTea Web'' version] (e.g. {{ic|1.4.1}}). This is independent of the ''IcedTea'' version.
  
{{Note|If you use a non-reparenting window manager and Java 6, you should uncomment the corresponding line in {{Ic|/etc/profile.d/openjdk6.sh}}}}
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=== Oracle Java SE ===
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The Oracle implementations of JRE and JDK are available in the [[AUR]]: {{AUR|jre}} and {{AUR|jdk}}.
  
=== Oracle JVM ===
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==== Java SE 6 ====
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The [[AUR]] contains {{AUR|jre6}} and {{AUR|jdk6}}, which are the Oracle implementations of Java SE 6.
  
Prior to the [http://mailman.archlinux.org/pipermail/arch-general/2011-August/021671.html retirement of the Oracle DLJ], it was possible to simply install the {{Ic|jre}} and {{Ic|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 {{Ic|java-runtime}} and {{Ic|java-environment}}.
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==== JDK-compat ====
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The Oracle JDK (6 and 7) can also be installed in parallel with another Java installation (for example OpenJDK). The packages can be found in the [[AUR]]: {{AUR|jdk6-compat}} and {{AUR|jdk7-compat}}.
  
AUR contains packages for {{AUR|jre}} and {{AUR|jdk}}, the Oracle implementations of Java.
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=== Oracle JRockit ===
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[http://www.oracle.com/technetwork/middleware/jrockit/overview/index.html JRockit] is a JIT version of Java, provided by Oracle and available as {{AUR|jrockit}} from the [[AUR]].
  
=== Oracle JVM (Java 6) ===
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=== VMkit ===
 
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[http://vmkit.llvm.org/index.html VMkit] is an LLVM-based framework for JIT virtual machines. J3 is a JVM running on VMkit. The webpage can be found here: [http://vmkit.llvm.org/get_started.html vmkit]. J3 depends on the GNU classpath libraries, but may also work with the Apache class path libraries.
AUR contains package for {{AUR|jre6}} and {{AUR|jdk6}}, which are the Oracle implementations of Java SE 6.  These packages conflict with the other java packages, so there are also {{AUR|jre6-compat}} and {{AUR|jdk6-compat}} which can be used along side other java installations.
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=== Kaffe (Discontinued) ===
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[http://www.kaffe.org/ 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|kaffe-git}}. The Kaffe VM is redistributed according to the GPL license.
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=== BEA JRockit JIT JVM (+JDK) ===
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[[Wikipedia:JRockit|JRockit]] is JIT version of Java, provided by Oracle and available from the AUR here: {{AUR|jrockit}}.
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=== VMkit LLVM-based JIT VM ===
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[http://vmkit.llvm.org/index.html 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|vmkit-svn}}. J3 depends on the GNU classpath libraries, but may also work with the Apache class path libraries.
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=== Parrot VM ===
 
=== Parrot VM ===
The [http://www.archlinux.org/packages/?q=parrot Parrot VM] offers experimental [http://trac.parrot.org/parrot/wiki/Languages support for Java] through two different methods: Either as a [http://code.google.com/p/parrot-jvm/ Java VM bytecode translator] or as a [https://github.com/chrisdolan/perk Java compiler targeting the Parrot VM]. Available in the AUR package {{AUR|parrot-git}}.
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[http://www.parrot.org/ Parrot] is a VM that offers experimental [http://trac.parrot.org/parrot/wiki/Languages support for Java] through two different methods: Either as a [http://code.google.com/p/parrot-jvm/ Java VM bytecode translator] or as a [https://github.com/chrisdolan/perk Java compiler targeting the Parrot VM]. {{Pkg|parrot}} is available in the [[official repositories]] and {{AUR|parrot-git}} in the [[AUR]].
  
 
== Troubleshooting ==
 
== Troubleshooting ==
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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 &ldquo;<code>LG3D</code>,&rdquo; the non-re-parenting window manager [http://en.wikipedia.org/wiki/Project_Looking_Glass written by Sun, in Java].
 
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 &ldquo;<code>LG3D</code>,&rdquo; the non-re-parenting window manager [http://en.wikipedia.org/wiki/Project_Looking_Glass written by Sun, in Java].
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=== Fonts are Illegible ===
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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 ms-fonts are being used. Install {{AUR|ttf-ms-fonts}} from the AUR.
  
 
== Tips and tricks ==
 
== Tips and tricks ==
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=== GTK LookAndFeel ===
 
=== GTK LookAndFeel ===
 
If your Java programs look ugly, you may want to set up the default look and feel for the swing components: {{Ic|1=swing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel}}.
 
If your Java programs look ugly, you may want to set up the default look and feel for the swing components: {{Ic|1=swing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel}}.
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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:
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{{Ic|1=swing.crossplatformlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel}}.
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=== Symlinks change ===
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Typically, OpenJDK installation creates symlinks in {{Ic|/usr/bin}} for java, javac ... etc. If you want to change these symlinks to any other JDK (e.g. if you installed environment-compat packages of Oracle JDK), [https://github.com/d1x/linux-utils/blob/master/replace-java-symlinks.sh this] script might be handy for you.

Revision as of 08:44, 30 December 2013

Related articles

"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

Installation

The only supported JVM implementation in Arch Linux is the open source OpenJDK. It is nearly perfect, and it should not be necessary to install Oracle's proprietary version of Java. If you want to install Oracle Java alongside OpenJDK, see #JDK-compat.

Note: After installation, the Java environment will need recognized by the shell ($PATH variable and $JAVA_HOME). This can be done from the command line by sourcing /etc/profile, and for Desktop Environments it is likely a logout/login will be necessary.

OpenJDK

The OpenJDK Java runtime environment (JRE) can be installed with the package jre7-openjdk, available in the official repositories. There is also a Java development kit (JDK) available with the package jdk7-openjdk.

If you want Java functionality in browsers (Java applets and Java Web Start), install icedtea-web-java7. For more details see Browser Plugins#Java (IcedTea).

Flagging packages as out-of-date

Oracle Java SE

The Oracle implementations of JRE and JDK are available in the AUR: jreAUR and jdkAUR.

Java SE 6

The AUR contains jre6AUR and jdk6AUR, which are the Oracle implementations of Java SE 6.

JDK-compat

The Oracle JDK (6 and 7) can also be installed in parallel with another Java installation (for example OpenJDK). The packages can be found in the AUR: jdk6-compatAUR and jdk7-compatAUR.

Oracle JRockit

JRockit is a JIT version of Java, provided by Oracle and available as jrockitAUR from the AUR.

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 instructions in MySQL article.

Java sound with Pulseaudio

Note: This procedure is likely to be relevant for previous version of Java (Java 6) only.

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 java.bin

# mv /opt/java/jre/bin/java /opt/java/jre/bin/java.bin

Then, create a new launcher script at /opt/java/jre/bin/java

#!/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

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 occuring 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, many users prefer to impersonate “LG3D,” the non-re-parenting window manager written by Sun, in Java.

Fonts are Illegible

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 ms-fonts are being used. Install ttf-ms-fontsAUR from the AUR.

Tips and tricks

Note: Suggestions in this section are applicable to all applications, using explicitly installed (external) Java runtime. Some applications are bundled with own (private) runtime or use own mechanics for GUI, font rendering, etc., so none of written below is guaranteed to work.

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 all users):

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

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.

Symlinks change

Typically, OpenJDK installation creates symlinks in /usr/bin for java, javac ... etc. If you want to change these symlinks to any other JDK (e.g. if you installed environment-compat packages of Oracle JDK), this script might be handy for you.