Null pointer Error while linking a .css file in a different folder

Question

I have a JavaFx OSGi project:

src
    main.java.ui.impl
        UI.java
    main.resources
        ui.css

I'm getting a null pointer whene I try to link up the Scene to the CSS file ui.css as follows:

scene.getStylesheets().add(this.getClass().getResource("../../../ui.css").toExternalForm());

I've even tried to have the ui.css in the folder/ package ui directly above the package impl where UI.java is located, but still null pointer

scene.getStylesheets().add(this.getClass().getResource("../ui.css").toExternalForm());

It only works where all the files are placed in the same package:

scene.getStylesheets().add(this.getClass().getResource("ui.css").toExternalForm());

What is the right way to go about this? What am I doing wrong?

Thank you all in advance.

UPDATE

Source repository on GitHub >>> javafx-osgi-example-master

Be sure to first install Amdatu from the Eclipse marketplace

James_D · Accepted Answer · 2016-03-28 17:06:28Z

1

Specify it relative to the class path, either by starting the path with a leading /, or by retrieving the resource from the ClassLoader:

scene.getStylesheets().add(this.getClass().getResource("/ui.css").toExternalForm());

or

scene.getStylesheets().add(this.getClass().getClassLoader().getResource("ui.css").toExternalForm());

The problem with your code as it stands is that you are not providing a valid resource name according to this specification. In particular:

A resource is identified by a string consisting of a sequence of substrings, delimited by slashes (/), followed by a resource name. Each substring must be a valid Java identifier.

and, of course, .. is not a valid Java identifier.

edited Mar 28, 2016 at 17:06

answered Mar 28, 2016 at 17:02

James_D

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3 Comments

Program-Me-Rev Over a year ago

What will it be if it is one package up? "/../ui.css"?

James_D Over a year ago

It can't be one package up from the root of the classpath, by definition of "root".

Program-Me-Rev Over a year ago

Hi @James_D Thank you for the responses you gave to my question. Your suggestions should be working, but for some reason they won't work with my project. I updated my question with a link to the project source files on GitHub. (javafx-osgi-example-master). I was hoping you could take a look and offer a suggestion. Thank you for your help so far

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