Core Java packages
Fedora allows multiple Java Virtual Machines (JVMs) to be packaged independently. Java packages should not directly depend on any particulat JVM, but instead require one of three virtual JVM packages depending of what Java funtionality is required.
This package provides a working Java Runtime Environment (JRE) with some functionality disabled. Graphics and audio support may be unavailable in this case. `java-headless` provides functionality that is enough for most of packages and avoids pulling in a number of graphics and audio libraries as dependencies. Requirement on `java-headless` is appropriate for most of Java packages.
Includes the same base functionality as `java-headless`, but also implements audio and graphics subsystems. Packages should require `java` if they need some functionality from these subsystems, for example creating GUI using AWT library.
Provides full Java Development Kit (JDK). In most cases only packages related to Java development should have runtime dependencies on `java-devel`. Runtime packages should require `java-headless` or `java`. Some packages not strictly related to java development need access to libraries included with JDK, but not with JRE (for example `tools.jar`). That's one of few cases where requiring java-devel may be necessary.
Packages that require minimal Java standard version can add versioned dependencies on one of virtual packages providing Java environment. For example if packages depending on functionality of JDK 8 can require `java-headless >= 1:1.8.0`.
Epoch in versions of JVM packages
For compatibility with JPackage project packages providing Java 1.6.0 or later use epoch equal to `1`. This was necessary because package `java-1.5.0-ibm` from JPackage project had epoch `1` for some reason, so packages providing other implementations of JVM also had to use non-zero epoch in order to keep version ordering correct.
Java Packages Tools
Java Packages Tools are packaged as severas binary RPM packages
This package provides a complete environment which is required to build Java packages using Apache Maven build system. This includes a default system version of Java Development Kit (JDK), Maven, a number of Maven plugins commonly used to build packages, various macros and utlilty tools. `maven-local` is usually declared as build dependency of Maven packages.
Similairly to `maven-local`, this package provides an environment required to build Java packages using Gradle as a build tool.
Analogously to `maven-local` and `gradle-local`, this package provides an environment required to build Java packages using Apache Ivy as dependency manager.