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* Out-of-date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This wiki page is no longer maintained.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