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List:       openjdk-openjfx-dev
Subject:    RFR: 8256362: JavaFX must warn when the javafx.* modules are loaded from the classpath
From:       Kevin Rushforth <kcr () openjdk ! java ! net>
Date:       2020-11-17 18:16:05
Message-ID: CdqGuTrOqqTyUY-x8xzYbVhC6IDlKkcemAMswzVlrNU=.1312ca8a-2fb2-4d35-944f-84de91fc157b () github ! com
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This fix adds documentation and a warning to clarify that loading the JavaFX modules \
from the classpath is not a supported configuration. This will not affect deployments \
that put the JavaFX modular jars on the classpath, but will simply warn that it is an \
unsupported mode.

JavaFX is built and distributed as a set of named modules, each in its own modular \
jar file. This supports running both modular and non-modular applications.

The JavaFX runtime expects its classes to be loaded from a set of named `javafx.*` \
modules, and does not support loading those modules from the classpath. The Java \
launcher will fail to load applications that extend `javafx.application.Application` \
unless the `javafx.graphics` module is on the module path.

Applications that do not extend `javafx.application.Application` can be loaded even \
if the `javafx.*` classes are loaded from the classpath, but this is an unsupported \
configuration.

This creates the perception that there is a problem with the standard case of loading \
a subclass of `javafx.application.Application`, since it fails to load in the case \
where the JavaFX classes are loaded from the classpath. Further, allowing \
applications to run in an unsupported mode that likely has bugs creates a maintenance \
burden. Another problem is that when the JavaFX classes are loaded from the \
classpath, it breaks encapsulation, since we mo longer get the benefit of the java \
module system.

The primary reason given for application deployments loading the javafx modules on \
the classpath usually boils down to one of tooling support, although both gradle and \
maven now support modules as do all of the popular IDEs.

-------------

Commit messages:
 - 8256362: JavaFX must warn when the javafx.* modules are loaded from the classpath

Changes: https://git.openjdk.java.net/jfx/pull/354/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=354&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256362
  Stats: 39 lines in 4 files changed: 39 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/354.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/354/head:pull/354

PR: https://git.openjdk.java.net/jfx/pull/354


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