Java Utililty Methods JFileChooser Filter

if (!dir.isDirectory()) {
    throw new IllegalArgumentException("Not a directory:" + dir);
File[] list = ((filter == null) ? dir.listFiles() : dir.listFiles(filter));
File latestFile = null;
long latest = Long.MIN_VALUE;
for (int i = 0; i < list.length; i++) {
    long tmp = list[i].lastModified();
...

return new FileFilter() {
    @Override
    public boolean accept(File f) {
        return f.isDirectory() || f.getName().endsWith(".wav");
    @Override
    public String getDescription() {
        return "WAV sound files";
...

if (filter.accept(file)) {
    list.add(file);
    if (file.isFile()) {
        return;
if (file.isDirectory()) {
    File files[] = file.listFiles();
...

List<File> arrayList = new ArrayList<>();
File[] files;
if (!file.exists() || file.isFile()) {
    return null;
list(arrayList, file, filter);
files = new File[arrayList.size()];
arrayList.toArray(files);
...

ArrayList<File> list = new ArrayList<File>();
File[] files;
if (!file.exists() || file.isFile()) {
    return null;
list(list, file, filter);
files = new File[list.size()];
list.toArray(files);
...

return new FileFilter() {
    public boolean accept(File file) {
        if (file.isDirectory()) {
            return true;
        for (String extension : types) {
            if (file.getName().toLowerCase().endsWith(extension)) {
                return true;
...

if (extensions == null)
    return null;
int numExtensions = 0;
for (int ii = 0; ii < extensions.length; ++ii)
    if (extensions[ii] != null)
        numExtensions = numExtensions + 1;
String[] nne = new String[numExtensions];
int iext = 0;
...

return new javax.swing.filechooser.FileFilter() {
    @Override
    public boolean accept(java.io.File f) {
        if (f.isDirectory()) {
            return true;
        int pos = f.getName().lastIndexOf('.');
        if (pos == -1) {
...

if (file == null || filter == null || filter.accept(file)) {
    return file;
String fileName = file.getName();
int index = fileName.lastIndexOf(".");
if (index > 0) {
    fileName = fileName.substring(0, index);
final String extension = filter.toString();
if (extension.matches("(\\w)*")) {
    String newFileName = fileName + "." + extension;
    File newFile = new File(file.getParent(), newFileName);
    return newFile;
return file;

return new java.io.FileFilter() {
    public boolean accept(File f) {
        return ((filter == null) ? true : filter.accept(f));
};