Why am I getting the above error on the code bellow  (FileSaveService and FileContents work just fine):

com.hrtrust.ps.scanner;

javax.jnlp.FileOpenService;

javax.jnlp.FileSaveService;

javax.jnlp.FileContents;

javax.jnlp.ServiceManager;

javax.jnlp.UnavailableServiceException;

java.io.*;

javax.jnlp.ExtendedService;

class FileHandler {

static private FileOpenService fos = null;

static private FileSaveService fss = null;

static private FileContents fc = null;

static private ExtendedService exs = null;

// retrieves a reference to the JNLP services

private static synchronized void initialize() {

if (fss != null) {

return;

try {

fos = (FileOpenService) ServiceManager.lookup("javax.jnlp.FileOpenService");

fss = (FileSaveService) ServiceManager.lookup("javax.jnlp.FileSaveService");

exs = (ExtendedService) ServiceManager.lookup("javax.jnlp.ExtendedService");        

catch (UnavailableServiceException e) {

fos = null;

fss = null;

exs = null;

public static FileContents getDLL(File dllFile) {

try {

fc = exs.openFile(dllFile);

catch (IOException ioe) {

ioe.printStackTrace(System.out);

return null;

return fc;

// displays open file dialog and reads selected file using FileOpenService

public static String open() {

try {

fc = fos.openFileDialog(null, null);

return readFromFile(fc);

catch (IOException ioe) {

ioe.printStackTrace(System.out);

return null;

// displays saveFileDialog and saves file using FileSaveService

public static void save(String txt) {

try {

// Show save dialog if no name is already given

if (fc == null) {

fc = fss.saveFileDialog(null, null,

new ByteArrayInputStream(txt.getBytes()), null);

// file saved, done

return;

// use this only when filename is known

if (fc != null) {

txt, fc);

catch (IOException ioe) {

ioe.printStackTrace(System.out);

// displays saveAsFileDialog and saves file using FileSaveService

public static void saveAs(String txt) {

try {

if (fc == null) {

// If not already saved. Save-as is like save

txt);

else {

fc = fss.saveAsFileDialog(null, null, fc);

txt);

catch (IOException ioe) {

ioe.printStackTrace(System.out);

private static void writeToFile(String txt, FileContents fc) throws IOException {

int sizeNeeded = txt.length() * 2;

if (sizeNeeded > fc.getMaxLength()) {

fc.setMaxLength(sizeNeeded);

os = new BufferedWriter(new OutputStreamWriter(fc.getOutputStream(true)));

os.write(txt);

os.close();

private static String readFromFile(FileContents fc) throws IOException {

if (fc == null) {

return null;

br = new BufferedReader(new InputStreamReader(fc.getInputStream()));

sb = new StringBuffer((int) fc.getLength());

line = br.readLine();

while (line != null) {

sb.append(line);

sb.append("\n");

line = br.readLine();

br.close();

return sb.toString();