Installing Java

Java is a popular programming language that allows you run programs on many platforms, including Fedora. If you want to create Java programs, you need to install a JDK (Java Development Kit). If you want to run a Java program, you can do that on a JVM (Java Virtual Machine), which is provided with the JRE (Java Runtime Environment). If in doubt, install the JDK because this is sometimes required even if the intention is not to write Java programs.

Many flavors of Java exist and also many versions of each flavor. If you want to just run a specific application, check the documentation of that software to see what versions of Java are supported or have been tested. Most Java applications run on one of the following:

• OpenJDK — an open-source implementation of the Java Platform, Standard Edition. This version is preferred, and included in Fedora.

• Oracle Java SE — a free JDK from Oracle. This version is not open-source and we recommend that it only be used if OpenJDK is not sufficient.

You can find the following Versions:

• Version (Ex. 8)

• Long Term Support or LTS

• Latest

Installing OpenJDK

To install OpenJDK from the Fedora repository:

• Run the following command to list available versions:

dnf search openjdk

• Copy the version of OpenJDK you want to install.

• Run the following command to install OpenJDK:

sudo dnf install <openjdk-package-name>

Examples:

sudo dnf install java-1.8.0-openjdk.x86_64

sudo dnf install java-11-openjdk.x86_64

sudo dnf install java-latest-openjdk.x86_64

Installing OpenJDK for development

In order to install the Java Development Kit, runtime environment and associated development tools.

sudo dnf install <openjdk-package-name>-devel

Examples:

sudo dnf install java-1.8.0-openjdk-devel.x86_64

sudo dnf install java-11-openjdk-devel.x86_64

sudo dnf install java-latest-openjdk-devel.x86_64

Installing Oracle Java SE

To install Oracle Java SE:

1. Navigate to Oracle Java SE downloads page, and choose the version of Java you wish to use.

2. Accept the license agreement and download the appropriate tar.gz file for your systems architecture. Do NOT use Oracle rpms as these are NOT compatible with fedora/openjdk packages. Download the tar.gz archive instead, unpack it somewhere and set to path if necessary.

Note: Always make sure to download latest version available.

Switching between Java Versions

You might have installed several versions of Java on your system, you can switch from one

After running this command, you will see a a list of all installed Java versions, select t

sudo alternatives --config java

Simply enter a selection number to choose which java executable should be used by default.

• verify:

java --version

JDK reference

See the following list of Java-related acronyms for reference:

JRE

Java Runtime Environment; equired to run Java code and applications

JVM

Java Virtual Machine; main component of the JRE

JDK

Java Development Kit; required only for development, coding

SDK

Software Development Kit; see JDK

JavaWS

Java Web Start is a framework to start application from the Internet

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 openjdk.java.net.

IcedTea

is a support project for OpenJDK (concern only developers) icedtea.classpath.org

IcedTea-Web

is the Java Web Start package (contains only JavaWS, no applets anymore); install to run JNPL files

applets

are obsolete technology; Not implemented in any recent package

JSE, J2SE, JEE, …​

obsolete acronyms for Java Standard & Enterprise Edition; JavaSE is like JRE

JDK components

The JDK has as its primary components a collection of programming tools, including:

appletviewer

this tool can be used to run and debug Java applets without a web browser

apt

the annotation-processing tool

extcheck

a utility which can detect JAR-file conflicts

idlj

the IDL-to-Java compiler. This utility generates Java bindings from a given Java IDL file.

jabswitch

the Java Access Bridge. Exposes assistive technologies on Microsoft Windows systems.

java

the loader for Java applications. This tool is an interpreter and can interpret the class files generated by the javac compiler. Now a single launcher is used for both development and deployment. The old deployment launcher, jre, no longer comes with Sun JDK, and instead it has been replaced by this new java loader.

javac

the Java compiler, which converts source code into Java bytecode

javadoc

the documentation generator, which automatically generates documentation from source code comments

jar

the archiver, which packages related class libraries into a single JAR file. This tool also helps manage JAR files.

javafxpackager

tool to package and sign JavaFX applications

jarsigner

the jar signing and verification tool

javah

the C header and stub generator, used to write native methods

javap

the class file disassembler

javaws

the Java Web Start launcher for JNLP applications

JConsole

Java Monitoring and Management Console

jdb

the debugger

jhat

Java Heap Analysis Tool (experimental)

jinfo

This utility gets configuration information from a running Java process or crash dump. (experimental)

jmap

This utility outputs the memory map for Java and can print shared object memory maps or heap memory details of a given process or core dump. (experimental)

jmc

Java Mission Control

jps

Java Virtual Machine Process Status Tool lists the instrumented HotSpot Java Virtual Machines (JVMs) on the target system. (experimental)

jrunscript

Java command-line script shell.

jstack

utility which prints Java stack traces of Java threads (experimental)

jstat

Java Virtual Machine statistics monitoring tool (experimental)

jstatd

jstat daemon (experimental)

keytool

tool for manipulating the keystore

pack200

JAR compression tool

policytool

the policy creation and management tool, which can determine policy for a Java runtime, specifying which permissions are available for code from various sources

VisualVM

visual tool integrating several command-line JDK tools and lightweight clarification needed] performance and memory profiling capabilities

wsimport

generates portable JAX-WS artifacts for invoking a web service.

xjc

Part of the Java API for XML Binding (JAXB) API. It accepts an XML schema and generates Java classes.

The JDK also comes with a complete Java Runtime Environment, usually called a private runtime, due to the fact that it is separated from the “regular” JRE and has extra contents. It consists of a Java Virtual Machine and all of the class libraries present in the production environment, as well as additional libraries only useful to developers, such as the internationalization libraries and the IDL libraries.

Additional resources

For Java in Fedora, see:

• java-devel mailing list

• Freenode IRC channel #fedora-java

• Ask Fedora about Java

For more information about Java in general, see:

• Wikipedia page for Java)

• OpenJDK homepage

• Oracle homepage for Java

To develop Java applications, consider the following open-source IDEs:

• NetBeans

• Eclipse

• IntelliJ IDEA