DirectoryChooserUI: reduce reflective win ShellFolder API usage

 - some internal methods are now public in FileSystemView and can be
   used instead of using reflection
 - remove calls to ShellFolder.getShellFolder(file) entirely

this hopefully fixes the mysterious NPEs on windows caused by
broken java.io.File instances with null paths.

ide/o.n.swing.dirchooser/src/org/netbeans/swing/dirchooser/DirectoryChooserUI.java

@@ -43,6 +43,7 @@
 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.lang.ref.WeakReference;
 import java.lang.reflect.Constructor;
@@ -272,7 +273,7 @@ private void updateUseShellFolder() {
             useShellFolder = false;
             File[] roots = fileChooser.getFileSystemView().getRoots();
             if (roots != null && roots.length == 1) {
-                File[] cbFolders = getShellFolderRoots();
+                File[] cbFolders = fileChooser.getFileSystemView().getChooserComboBoxFiles();
                 if (cbFolders != null && cbFolders.length > 0 && Arrays.asList(cbFolders).contains(roots[0])) {
                     useShellFolder = true;
                 }
@@ -328,54 +329,15 @@ private JComponent getPlacesBar() {
             return null;
         }
     }
-
-    /** Reflection alternative of
-     * sun.awt.shell.ShellFolder.getShellFolder(file)
-     */
-    private File getShellFolderForFile (File file) {
-        try {
-            Class<?> clazz = Class.forName("sun.awt.shell.ShellFolder");
-            return (File) clazz.getMethod("getShellFolder", File.class).invoke(null, file);
-        } catch (Exception exc) {
-            // reflection not succesfull, just log the exception and return null
-            Logger.getLogger(DirectoryChooserUI.class.getName()).log(
-                    Level.FINE, "ShellFolder can't be used.", exc);
-            return null;
-        }
-    }
 
-    /** Reflection alternative of
-     * sun.awt.shell.ShellFolder.getShellFolder(dir).getLinkLocation()
-     */
-    private File getShellFolderForFileLinkLoc (File file) {
+    private File getShellFolderForFileLinkLoc(File file) {
         try {
-            Class<?> clazz = Class.forName("sun.awt.shell.ShellFolder");
-            Object sf = clazz.getMethod("getShellFolder", File.class).invoke(null, file);
-            return (File) clazz.getMethod("getLinkLocation").invoke(sf);
-        } catch (Exception exc) {
-            // reflection not succesfull, just log the exception and return null
-            Logger.getLogger(DirectoryChooserUI.class.getName()).log(
-                    Level.FINE, "ShellFolder can't be used.", exc);
-            return null;
-        }
-
-    }
-
-    /** Reflection alternative of
-     * sun.awt.shell.ShellFolder.get("fileChooserComboBoxFolders")
-     */ 
-    private File[] getShellFolderRoots () {
-        try {
-            Class<?> clazz = Class.forName("sun.awt.shell.ShellFolder");
-            return (File[]) clazz.getMethod("get", String.class).invoke(null, "fileChooserComboBoxFolders");
-        } catch (Exception exc) {
-            // reflection not succesfull, just log the exception and return null
-            Logger.getLogger(DirectoryChooserUI.class.getName()).log(
-                    Level.FINE, "ShellFolder can't be used.", exc);
+            return fileChooser.getFileSystemView().getLinkLocation(file);
+        } catch (FileNotFoundException ex) {
             return null;
         }
     }
-    
+
     private void createBottomPanel(JFileChooser fc) {
         bottomPanel = new JPanel();
         bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.LINE_AXIS));
@@ -1864,11 +1826,9 @@ public String getName() {
      * Data model for a type-face selection combo-box.
      */
     private class DirectoryComboBoxModel extends AbstractListModel implements ComboBoxModel {
-        Vector<File> directories = new Vector<>();
-        int[] depths = null;
-        File selectedDirectory = null;
-        JFileChooser chooser = getFileChooser();
-        FileSystemView fsv = chooser.getFileSystemView();
+        private final Vector<File> directories = new Vector<>();
+        private int[] depths = null;
+        private File selectedDirectory = null;
 
         public DirectoryComboBoxModel() {
             // Add the current directory to the model, and make it the
@@ -1893,7 +1853,7 @@ private void addItem(File directory) {
             directories.clear();
 
             if(useShellFolder) {
-                directories.addAll(Arrays.asList(getShellFolderRoots()));
+                directories.addAll(Arrays.asList(fileChooser.getFileSystemView().getChooserComboBoxFiles()));
             } else {
                 directories.addAll(Arrays.asList(fileChooser.getFileSystemView().getRoots()));
             }
@@ -1911,8 +1871,7 @@ private void addItem(File directory) {
             }
 
             // create File instances of each directory leading up to the top
-            File sf = useShellFolder? getShellFolderForFile(canonical) : canonical;
-            File f = sf;
+            File f = canonical;
             Vector<File> path = new Vector<>(10);
 
 
@@ -1940,7 +1899,7 @@ private void addItem(File directory) {
                 }
             }
             calculateDepths();
-            setSelectedItem(sf);
+            setSelectedItem(canonical);
         }
 
         private void calculateDepths() {