getClass().getResource() 加载文件失败，File() 有效

Question

I'm trying to incorporate a css file to my JavaFX appllication, by the following snippet:

public void loadExternalCSS() {
      System.out.println("CLASSPATH: "+System.getProperty("java.class.path"));
      try{
        skinCSS = getClass().getResource("css/default_skin.css").toExternalForm();
      }
      catch(Exception e){
          System.err.println("Exception: " + e);
          e.printStackTrace(System.err);
      }
}

Which yields, at runtime:

java.lang.NullPointerException
    at 
robotikosanomologitos.RobotikosAnomologitos.loadExternalCSS(RobotikosAnomologitos.java:529)
    at robotikosanomologitos.RobotikosAnomologitos.start(RobotikosAnomologitos.java:491)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:745)

The weird thing is that a few lines above this function, I have a small function that reads from a properties file.

public void readPropertiesFile() {
        Properties props = new Properties();
        InputStream is;
        try {
            File f = new File("properties");
            is = new FileInputStream(f);
        }
        /* etcetera */
}

This works like a charm. The properties file is located at the root of the project directory, C:\\~my_projects_folder~\\RobotikosAnomologitos

After searching around for a solution , I saw that getClass().getResource() attempts to find a resource in the classpath. I tried printing the classpath at every run, and I get: RobotikosAnomologitos\\dist\\run125323585\\RobotikosAnomologitos.jar which is logical enough.

After looking inside this temporary folder while running the program, though, I can find no css folder nor css file.

But the file is indeed located in my working project directory, under RobotikosAnomologitos\\css\\default_skin.css . For some reason it doesn't make it in the classpath at runtime, causing getResource() to return null when looking for it.

Any ideas on how to include it?

---

EDIT: I forgot to mention that I have also placed css/default_skin.css under the src package, and shows up in Netbeans' package tree ( src/css/default_skin.css ).

In the same way, I have some graphics that are located under src/graphics/ which get loaded fine by getClass().getResourceAsStream() . Which also bafflesss me as to why the css file can't be found. Maybe it doesn't get compiled in the jar ?

Answer 1

If you call getResource() for a class and do not prepend a / , the path is considered to be relative to the package of the class.

If you've properly added the resources to the classpath, this should work:

 skinCSS = getClass().getResource("/css/default_skin.css").toExternalForm();

Answer 2

如果要使用getClass().getResource("css/default_skin.css").toExternalForm();检索，则需要在classpath添加css文件夹getClass().getResource("css/default_skin.css").toExternalForm();

Answer 3

Check if you are not using binary encode of CSS files (see Project Properties>Packaging). If you are using, the mentioned file extension should be ".bss".