JI-9056801 : Scene: Allow to add a stylesheet using a typed URL, not a stringified URL

Michael Binz michab66 at gmail.com
Wed Aug 22 18:47:09 UTC 2018

Hi all,

I opened a proposal for an extension of the javafx.scene.Scene API to allow
to add a stylesheet using a typed java.net.URL.

Currently the Scene class offers a list of stylesheet URLs in their
stringified representation accessible by Scene.getStylesheets().

The problem is that in some cases an URL instance encapsulates internal
state that gets lost in the conversion into its external form and back into
an URL instance, namely information on an URL handler. This ultimately
results in a failure (IOException file not found) when the Screen class
tries to load a stylesheet though code that loads the file contents using
URL#openStream() on the original URL instance can read the file contents

In my case the problem showed up when creating an executable jar file
containing my JavaFX application (using OneJar).  The application startup
in this case installs a customized Classloader that implements special
logic for accessing the jars contained classes,  This works transparently
for classes and resources, but the URLs returned by Class#getResource( name
) do not survive the conversion to string and back because of the described

There is a workaround that caches the resource in a temporary file and
passes this file's URL to the Scene's list of stylesheets, but this poses
other problems.
As a remark, other APIs in JavaFX use the same pattern of expecting
stringified URLs like the Image() constructor and have the same problem,
but offer alternative constructors accepting a stream which allows to solve
the problem nicely.

Please discuss and decide if the proposal can be added as a change request
for JavaFX.

Best wishes,

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