I came to this code while digging in this issue: https://netbeans.org/bugzilla/show_bug.cgi?id=268027 ("Performance issue: FileUtil.normalizedRef cache is cleaned too frequently")

... i just can't grasp why that lengthy way is really needed to get FileObject for a File :

 File#1 -> URI -> URL -> URI -> Path -> File#2 -> FileObject

   on this way of lookups && conversions File#1 and File#2 seems to be always equal (i.e. another instance will always point to the same file)
   and code finally always goes to FileBasedFileSystem.getFileObject().
   
   So the question is - why just not skip all these CPU consuming actions and directly call FileBasedFileSystem.getFileObject(File)?

        I've implemeted this via dirty hack in local sources (see below) - nothing seems to get broken

    
Below is full trail of this path in sources:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

 FileObject FileUtil.toFileObject(File file) :
    URL url = BaseUtilities.toURI(file).toURL();
    retVal = URLMapper.findFileObject(url);

    -> URLMapper.getInstances().iterator() -> getFileObjects(url);
       
       -> FileObject[] FileBasedURLMapper.getFileObjects():
       |
       |   File file = FileUtil.normalizeFile(BaseUtilities.toFile(url.toURI()));
       |
       |   -> File BaseUtilities.toFile(URI u) :
       |
       |      Paths.get(u).toFile();
       |
       |      -> Path Paths.get(URI uri)
       |
       |          for (FileSystemProvider provider: FileSystemProvider.installedProviders()) {
       |            if (provider.getScheme().equalsIgnoreCase(scheme)) {
       |              return provider.getPath(uri);
       |
       |      -> sun.nio.fs.WindowsPath.toFile()
       |
       |         return new File(toString());
       |               
       |  FileObject fo = FileBasedFileSystem.getFileObject(file, FileObjectFactory.Caller.ToFileObject);
       |               
       |    ->  FileObject FileBasedFileSystem.getFileObject(final File file, FileObjectFactory.Caller caller) {
       |        ...


Dirty hack:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

because FileBasedFileSystem is in 'Master Filesystem' and that module depends on 'File System API' where FileUtil.toFileObject(File file) is defined I've made a 'quick CDI' for that implementation:

openide.filesystems\src\org\openide\filesystems\FileUtil.java

    public final class FileUtil extends Object {

        /* Injection point :) */
        public static Function<File,FileObject> FileToFileObject;

        public static FileObject toFileObject(File file) {
            ...
            if( FileToFileObject != null ) {
                FileObject fo = FileToFileObject.apply(file);
                if( fo != null ) {
                    return fo;
                }
            }

masterfs\src\org\netbeans\modules\masterfs\filebasedfs\FileBasedFileSystem.java

public class FileBasedFileSystem extends FileSystem {

        static {
            /* Injection of implementation :) */
            FileUtil.FileToFileObject = (file) -> 
                    getFileObject(file, FileObjectFactory.Caller.ToFileObject);
        }

        public static FileObject getFileObject(final File file, FileObjectFactory.Caller caller) {
            ...
        }