= Java ''' [IMPORTANT] ====== This page was automatically converted from https://fedoraproject.org/wiki/Java It is probably * Badly formatted * Missing graphics and tables that do not convert well from mediawiki * Out-of-date * In need of other love Please fix it, remove this notice, and then add to `_topic_map.yml` Pull requests accepted at https://pagure.io/fedora-docs/quick-docs Once that is live, go to the original wiki page and add an `{{old}}` tag, followed by a note like .... {{admon/note|This page has a new home!| This wiki page is no longer maintained. Please find the up-to-date version at: https://docs.fedoraproject.org/whatever-the-url }} .... ====== ''' __TOC__ Java is about: * Communities: the https://www.jcp.org/[Java Comunity Process] to define the platform, but also https://community.oracle.com/community/java/jug[Java User Groups] * Platforms (JVM, JRE ...) to run applications on PC, mobiles, embedded devices https://en.wikipedia.org/wiki/Java_(software_platform) * Programming languages (Java is the most popular, but there are Scala, Groovy, Clojure ...) https://en.wikipedia.org/wiki/Java_(programming_language) What do you want to do: * If you came here because an *application ask for Java* (or JRE, JVM) *to be installed*, then simply install . * If it still does not work: ** Install javafx and icedtea-web packages as well. ** Lastly, and if the application *ask specifically for http://www.oracle.com/technetwork/java/javase/index.html[Oracle Java]*: See here #Oracle_version. * If *you want to develop, code, on the Java Platform*: See Java/Development. [[jre-jdk-jvm-jse-...]] JRE JDK JVM JSE ... ^^^^^^^^^^^^^^^^^^^ Some vocabulary, if you are lost: * *JRE* Java Runtime Environment. Required to run Java code and applications. Install . * *JVM* Java Virtual Machine. Main component of the JRE. * *JDK* Java Development Kit. Required only for development, coding. * *SDK* Software Development Kit. idem JDK * *JavaWS* https://en.wikipedia.org/wiki/Java_Web_Start[Java Web Start] is a framework to start application from the Internet * *JavaFX* https://en.wikipedia.org/wiki/JavaFX[JavaFX] is a plateform to create and deliver desktop and Rich Internet Apps. * *OpenJFX* is the JavaFX Open Source implementation * *OpenJDK* Open Source project behind the Java Platform http://openjdk.java.net/. * *IcedTea* is a support project for OpenJDK (concern only developers) http://icedtea.classpath.org/ * *IcedTea-Web* is the Java Web Start package (It contains only JavaWS, No Applets anymore.) Install to run *JNPL* files. * *Applets* Obsolete techno. Not implemented in any recent package. * *JSE*, *J2SE*, *JEE* ... obsolete acronyms for **J**ava **S**tandard & **E**nterprise **E**dition. _JavaSE_ is like _JRE_. [[what-is-in-java-openjdk-package]] What is in Java OpenJDK package ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ For most users, it is just another system library. It is not an application with a GUI, but it is required by some other applications to run. You might see a _OpenJDK Policy tool_ desktop application that comes with the package, but you should not have to use it. Beware that JavaFX and JavaWS are packaged separately! [[multiple-implementations]] Multiple implementations ~~~~~~~~~~~~~~~~~~~~~~~~ Fedora provides the Free . If this Open Source stack does not fulfil your requirements. Alternatives can be installed alongside or separately. The **J**ava **C**ommunity **P**rocess defines the specifications of the platform that many implements (IBM J9, Jikes, Zing, Zulu Dalvik ...). We will only focus on Oracle here. Multiple implementations can be installed side-by-side without interfering: * The link:alternatives_system[alternatives system] allows to switch from one to another. * An application can directly reference a specific Java installation * Some applications include a java platform, it is then transparent for the user. (But the package is bigger.) [[oracle-version]] Oracle version ^^^^^^^^^^^^^^ Some applications still ask for Oracle's implementation. It is mostly based on the OpenJDK Open Source project, but there is proprietary code and Fedora does not package non-free software. Installing Oracle Java is fine. Just beware *not* to use Oracle *RPM*, as it will kill OpenJDK default packages! Oracle provides a tarball: https://java.com/en/download/help/linux_x64_install.xml We recommend to simply unpack the archives (tarball) to your home folder and set to path if necessary. [[switching-alternatives]] Switching alternatives ^^^^^^^^^^^^^^^^^^^^^^ If you installed multiple Java implementations or version, you can configure your system to use one or another. *Developers*: beware that javac has its own independent alternative. i.e. to change the JDK, use _alternatives ... javac_! Switching is done using the link:alternatives_system[alternatives system] (_also used to change some other subsystems_). Java's subsystem name is surprisingly _java_ and typical commands include: .... # alternatives --display java .... .... # alternatives --config java .... See alternative's own documentation for more information for usage and parts involved. Should be noted that JRE implementations installed outside Fedora distribution, may not support alternatives and thus not be visible there. Then the symbolic links under directory _/etc/alternatives_ must be manually fixed. [[java-packages-in-fedora]] Java packages in Fedora ----------------------- There are many aliases for OpenJDK package, see http://pkgs.fedoraproject.org/cgit/rpms/java-1.8.0-openjdk.git/tree/java-1.8.0-openjdk.spec or do "dnf repoquery --provides java-1.8.0-openjdk". You can use any of the following names: * java * java-1.8.0 * java-1.8.0-openjdk * java-openjdk * jre * jre-1.8.0 * jre-1.8.0-openjdk * jre-openjdk .... dnf install java-1.8.0-openjdk .... might be the most safe (until 1.8 is EOL.) *Note* that Java Web Start (*JavaWS*) and *JavaFX* are packaged separately 'icedtea-web' and 'javafx' respectively. Typically, without JavaFX, you may have error like: .... java -jar scram.jar Error: Could not find or load main class com.frequal.scram.designer.jfx.Main .... .... dnf install icedtea-web javafx .... [[communicate]] Communicate ----------- You can subscribe to https://admin.fedoraproject.org/mailman/listinfo/java-devel[java-devel list] or talk to us in irc://irc.freenode.net/fedora-java[#fedora-java] Freenode IRC channel. Read Communicate page for more information. [[see-also]] See Also -------- * Java/FAQ * Java/Troubleshooting * https://Ask.FedoraProject.org/en/questions/scope:all/sort:activity-desc/tags:java/page:1/[Ask Fedora about Java] * https://bugzilla.redhat.com/buglist.cgi?component=java-1.8.0-openjdk&product=Fedora&bug_status=NEW&bug_status=ASSIGNED&bug_status=MODIFIED&bug_status=ON_DEV&bug_status=ON_QA&order=bugs.votes,bugs.bug_id[Java-1.8.0-OpenJDK bugs] * SIGs/Java [[references]] References ---------- * http://openjdk.java.net/[OpenJDK Home] * https://wiki.openjdk.java.net/[OpenJDK Wiki] * http://jpackage.org/[Jpackage.org] Category:Java Category:Language-specific_SIGs ''' See a typo, something missing or out of date, or anything else which can be improved? 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