Java - ArchWiki

# Java

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Related articles

- Java Package Guidelines
- Java Runtime Environment fonts

From the 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.

Arch Linux officially supports the open source OpenJDK versions 7, 8, 10, 11, and 12. 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.

## Installation

Note:

- Arch Linux officially only supports the OpenJDK implementation.
- After installation, the Java environment will need to be recognized by the shell (`$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 are respectively pulled as dependency, named java-runtime-common (containing common files for Java Runtime Environments) and java-environment-common (containing common files for Java Development Kits). The provided environment file `/etc/profile.d/jre.sh` points to a linked location `/usr/lib/jvm/default/bin`, set by the `archlinux-java` helper script. The links `/usr/lib/jvm/default` and `/usr/lib/jvm/default-runtime` should always be edited with `archlinux-java`. This is used to display and point to a working default Java environment in `/usr/lib/jvm/java-${JAVA_MAJOR_VERSION}-${VENDOR_NAME}` or a Java runtime in `/usr/lib/jvm/java-${JAVA_MAJOR_VERSION}-${VENDOR_NAME}/jre`.

Most executables of the Java installation are provided by direct links in `/usr/bin`, while others are available in `$PATH`. The script `/etc/profile.d/jdk.sh` is no longer provided any package.

### OpenJDK

OpenJDK is an open-source implementation of the Java Platform, Standard Edition (Java SE).

Headless JRE
  The minimal Java runtime - needed for executing non-GUI Java programs.
Full JRE
  Full Java runtime environment - needed for executing Java GUI programs, depends on headless JRE.
JDK
  Java Development Kit - needed for Java development, depends on full JRE.

Version | Headless JRE | Full JRE | JDK | Documentation | Sources
--- | --- | --- | --- | --- | ---
OpenJDK 12 | jre-openjdk-headless | jre-openjdk | jdk-openjdk | openjdk-doc | openjdk-src
OpenJDK 11 | jre11-openjdk-headless | jre11-openjdk | jdk11-openjdk | openjdk11-doc | openjdk11-src
OpenJDK 10 | jre10-openjdk-headless | jre10-openjdk | jdk10-openjdk | openjdk10-doc | openjdk10-src
OpenJDK 8 | jre8-openjdk-headless | jre8-openjdk | jdk8-openjdk | openjdk8-doc | openjdk8-src
OpenJDK 7 | jre7-openjdk-headless | jre7-openjdk | jdk7-openjdk | openjdk7-doc | openjdk7-src

IcedTea-Web — Java Web Start and the deprecated Java browser plugin.

  https://icedtea.classpath.org/wiki/IcedTea-Web || icedtea-web

OpenJFX 8 — The open-source implementation of JavaFX. You do not need to install this package if you are making use of Java SE (the Oracle's implementation of JRE and JDK described below). This package only concerns users of the open source implementation of Java (OpenJDK project).

  https://openjdk.java.net/projects/openjfx/ || java-openjfx, java-openjfx-doc, java-openjfx-src

OpenJFX — Latest OpenJFX community build.

  https://openjfx.io/ || java-openjfx-binAUR

OpenJDK EA — OpenJDK Early-Access Build for latest development version.

  https://jdk.java.net || java-openjdk-ea-binAUR

OpenJFX EA — OpenJFX Early-Access Build for latest development version.

  https://openjfx.io/ || java-openjfx-ea-binAUR

### Other implementations

Java SE — Oracle's implementation of JRE and JDK.

  https://www.oracle.com/technetwork/java/javase/downloads/index.html || jreAUR jre9AUR jre8AUR jre7AUR jre6AUR jdkAUR jdk9AUR jdk8AUR jdk7AUR jdk6AUR jdk5AUR jdk-develAUR

OpenJ9 — Eclipse's implementation of JRE, contributed by IBM.

  https://www.eclipse.org/openj9/ || jdk9-openj9-binAUR jdk8-openj9-binAUR

IBM J9 — IBM's implementation of the eighth edition of JRE.

  https://developer.ibm.com/javasdk/ || jdk8-j9-binAUR jdk7-j9-binAUR jdk7r1-j9-binAUR

Parrot VM — a VM with experimental support for Java [1] through two different methods: either as a Java VM bytecode translator, or as a Java compiler targeting the Parrot VM.

  http://www.parrot.org/ || parrotAUR

Note: 32-bit versions of Java SE can be found by prefixing `bin32-`, e.g. bin32-jreAUR and bin32-jdkAUR. They use java32-runtime-commonAUR, which functions as java-runtime-common by suffixing with `32`, e.g. `java32`. The same analogy applies to java32-environment-commonAUR, which is only used by 32-bit JDK packages.

### Development tools

For integrated development environments, see List of applications#Integrated development environments and the Java IDEs subsection specifically.

To discourage reverse engineering an obfuscator like proguardAUR can be used.

#### Decompilers

- Bytecode Viewer — Java reverse engineering suite, including a decompiler, editor and debugger.

  https://bytecodeviewer.com || bytecode-viewerAUR

- CFR — Java decompiler, supporting modern features of Java 9, 10 and beyond.

  https://www.benf.org/other/cfr/ || cfrAUR

- Fernflower — Analytical decompiler for Java, developed as part of IntelliJ IDEA.

  https://github.com/JetBrains/intellij-community/tree/master/plugins/java-decompiler/engine || fernflower-gitAUR

- JAD — Unmaintained Java decompiler.

  https://varaneckas.com/jad || jad

- JD-Core-java — Thin-wrapper for the Java Decompiler.

  https://github.com/nviennot/jd-core-java || jd-core-javaAUR

- Krakatau — Java decompiler, assembler, and disassembler.

  https://github.com/Storyyeller/Krakatau || krakatau-gitAUR

- Procyon decompiler — Experimental Java decompiler, inspired by ILSpy and Mono.Cecil.

  https://bitbucket.org/mstrobel/procyon/wiki/Java%20Decompiler || procyon-decompilerAUR, GUI: luytenAUR

## Switching between JVM

The 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

Tip: To see possible `<JAVA_ENV_NAME>` names, use `archlinux-java status`.

Note that `archlinux-java` will not let you set an invalid Java environment. In the previous example, jre8-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 an invalid Java environment link is set, calling the `archlinux-java fix` command tries to fix it. 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 package "OpenJDK 8" will be considered first in this order, then other installed environments.

    # archlinux-java fix

### Launching an application with the non-default java version

If you want to launch an application with another version of java than the default one (for example if you have both version jre7 and jre8 installed on your system), you can wrap your application in a small bash script to locally change the default PATH of java. For example if the default version is jre7 and you want to use jre8:

    #!/bin/sh

    export PATH=/usr/lib/jvm/java-8-openjdk/jre/bin/:$PATH
    exec /path/to/application "$@"

## Package pre-requisites to support `archlinux-java`

Note: This info also applies to `archlinux32-java` for 32-bit Java packages, with the proper inclusion of `32` to the package/executable names, where applicable.

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` nor `java-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` or `java-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

## 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 MariaDB#Grant remote access.

### IntelliJ IDEA

If you have faced the error `The selected directory is not a valid home for JDK` with the system java sdk path, you have to install a new jdk in octopi or with pacman, then select the new java sdk as the IntelliJ IDEA's JDK.

### 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 or Ratpoison.

    $ 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.

### 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.

### Applications not resizing with WM, menus immediately closing

The standard Java GUI toolkit has a hard-coded list of "non-reparenting" window managers. If using one that is not on that list, there can be some problems with running some Java applications. One of the most common problems is "gray blobs", when the Java application renders as a plain gray box instead of rendering the GUI. Another one might be menus responding to your click, but closing immediately.

There are several things that may help:

- For jre7-openjdk or jre8-openjdk, append the line `export _JAVA_AWT_WM_NONREPARENTING=1` in `/etc/profile.d/jre.sh`. Then, source the file `/etc/profile.d/jre.sh` or log out and log back in.
- For Oracle's JRE/JDK, use SetWMName. However, its effect may be canceled when also using `XMonad.Hooks.EwmhDesktops`. In this case, appending

    >> setWMName "LG3D"

to the `LogHook` may help.

See [2] for more information.

### System freezes when debugging JavaFX Applications

If your system freezes while debugging a JavaFX Application, you can try to supply the JVM option `-Dsun.awt.disablegrab=true`.

See https://bugs.java.com/view_bug.do?bug_id=6714678

### JavaFX's MediaPlayer constructor throws an exception

Creating instance of MediaPlayer class from JavaFX's sound modules might throw following exception (both Oracle JDK and OpenJDK)

    ... (i.e. FXMLLoader construction exceptions) ...
    Caused by: MediaException: UNKNOWN : com.sun.media.jfxmedia.MediaException: Could not create player! : com.sun.media.jfxmedia.MediaException: Could not create player!
     at javafx.scene.media.MediaException.exceptionToMediaException(MediaException.java:146)
     at javafx.scene.media.MediaPlayer.init(MediaPlayer.java:511)
     at javafx.scene.media.MediaPlayer.<init>(MediaPlayer.java:414)
     at <constructor call>
    ...

which is a result of some incompatibilities of JavaFX with modern ffmpeg build delivered within Arch Linux repository.

Working solution is to install ffmpeg-compat-55AUR.

See https://www.reddit.com/r/archlinux/comments/70o8o6/using_a_javafx_mediaplayer_in_arch/

### Java applications cannot open external links

If a Java application is not able to open a link to, for example, your web browser, install gvfs. This is required by the Desktop.Action.BROWSE method. See [3]

### Error initializing QuantumRenderer: no suitable pipeline found

Possible issues / solutions:

- GTK2 is missing. Install gtk2
- OpenJFX is missing. Install java-openjfx

## 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 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: `-Dawt.useSystemAAFontSettings=on`, `-Dswing.aatext=true`

See Java Runtime Environment fonts for more detailed information.

### Silence 'Picked up _JAVA_OPTIONS' message on command line

Setting the _JAVA_OPTIONS environment variables makes java (openjdk) write to stderr messages of the form: 'Picked up _JAVA_OPTIONS=...'. To suppress those messages in your terminal you can unset the environment variable in your shell startup files and alias java to pass those same options as command line arguments:

    _SILENT_JAVA_OPTIONS="$_JAVA_OPTIONS"
    unset _JAVA_OPTIONS
    alias java='java "$_SILENT_JAVA_OPTIONS"'

### 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 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`.

#### GTK3 Support

In Java releases prior to version 9, the GTK LookAndFeel is linked against GTK2, whilst many newer desktop applications use GTK3. This incompatibility between GTK versions may break applications utilizing Java plugins with GUI, as the mixing of GTK2 and GTK3 in the same process is not supported (for example, LibreOffice 5.0).

Since Java 9, the GTK LookAndFeel can be run against GTK versions `2`, `2.2` and `3`, defaulting to GTK2. This can be overridden by setting the following property:

`jdk.gtk.version=3`

### Better 2D performance

Switching to OpenGL-based hardware acceleration pipeline will improve 2D performance

    export _JAVA_OPTIONS='-Dsun.java2d.opengl=true'

Note: Enabling this option may cause the UI of software like JetBrains IDEs misbehave, making them drawing windows, popups and toolbars partially.

### Non-reparenting window managers / Grey window / Programs not drawing properly

Non-reparenting window managers user should set the following environment variable in their `.xinitrc`

    export _JAVA_AWT_WM_NONREPARENTING=1

Not setting this may result in java programs not being drawn properly.

## See also

- Introduction to Programming Using Java

Categories:

- Programming languages
- Oracle