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<div class="messagebox" style="float: right; margin-left: 10px;">__TOC__</div> | <div class="messagebox" style="float: right; margin-left: 10px;">__TOC__</div> | ||
Java is about: | Java is about: | ||
* Communities: the [https://www.jcp.org/ Java | * Communities: the [https://www.jcp.org/ Java Community 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) | * 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) | * Programming languages (Java is the most popular, but there are Scala, Groovy, Clojure ...) https://en.wikipedia.org/wiki/Java_(programming_language) | ||
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** Install javafx and icedtea-web packages as well. | ** 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]]. | ** 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]]. | * If '''you want to develop, code, on the Java Platform''': See [[Java/Development]]. | ||
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* '''JDK''' Java Development Kit. Required only for development, coding. | * '''JDK''' Java Development Kit. Required only for development, coding. | ||
* '''SDK''' Software Development Kit. idem JDK | * '''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 | * '''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 | * '''JavaFX''' [https://en.wikipedia.org/wiki/JavaFX JavaFX] is a platform to create and deliver desktop and Rich Internet Apps. | ||
* '''OpenJFX''' is the JavaFX Open Source implementation | * '''OpenJFX''' is the JavaFX Open Source implementation | ||
* '''OpenJDK''' Open Source project behind the Java Platform http://openjdk.java.net/. | * '''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''' 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. | * '''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. | * '''Applets''' Obsolete techno. Not implemented in any recent package. | ||
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== Multiple implementations == | == Multiple implementations == | ||
Fedora provides the Free {{package|java-1.8.0-openjdk}}. If this Open Source stack does not | Fedora provides the Free {{package|java-1.8.0-openjdk}}. If this Open Source stack does not fulfill 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. | 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: | Multiple implementations can be installed side-by-side without interfering: | ||
* The [[alternatives system]] allows to switch from one to another. | * The [[alternatives system]] allows to switch from one to another. | ||
* An application can directly reference a specific Java installation | * 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.) | * Some applications include a java platform, it is then transparent for the user. (But the package is bigger.) | ||
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=== 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. | 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! | Installing Oracle Java is fine. Just beware '''not''' to use Oracle '''RPM''', as it will kill OpenJDK default packages! | ||
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=== Switching alternatives === | === Switching alternatives === | ||
If you installed multiple Java implementations or version, you can configure your system to use one or another. | 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''! | '''Developers''': beware that javac has its own independent alternative. i.e. to change the JDK, use ''alternatives ... javac''! | ||
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Typically, without JavaFX, you may have error like: | Typically, without JavaFX, you may have error like: | ||
<pre>java -jar scram.jar | <pre>java -jar scram.jar | ||
Error: Could not find or load main class com.frequal.scram.designer.jfx.Main</pre> | Error: Could not find or load main class com.frequal.scram.designer.jfx.Main</pre> | ||
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= 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] | 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] Libera Chat IRC channel. Read [[Communicate]] page for more information. | ||
= See Also = | = See Also = | ||
* [[Java/FAQ]] | * [[Java/FAQ]] | ||
* [[Java/Troubleshooting]] | * [[Java/Troubleshooting]] | ||
Latest revision as of 15:41, 14 July 2021
Java is about:
- Communities: the Java Community Process to define the platform, but also 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
java-1.8.0-openjdk - If it still does not work:
- Install javafx and icedtea-web packages as well.
- Lastly, and if the application ask specifically for Oracle Java: See here #Oracle_version.
- If you want to develop, code, on the Java Platform: See Java/Development.
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 Java Web Start is a framework to start application from the Internet
- JavaFX JavaFX is a platform 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 Java Standard & Enterprise Edition. JavaSE is like JRE.
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
Fedora provides the Free 
java-1.8.0-openjdk
The Java Community Process 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 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
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
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 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
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
You can subscribe to java-devel list or talk to us in #fedora-java Libera Chat IRC channel. Read Communicate page for more information.
See Also