Java Utililty Methods Folder Read

if (f == null)
    throw new RuntimeException("The passed file was null", new Throwable());
final String name = f.getName();
final int index = name.indexOf('.');
if (index == -1)
    return name;
return name.substring(0, index);

Set list = new TreeSet();
StringTokenizer st = new StringTokenizer(System.getProperty("java.class.path"), File.pathSeparator);
while (st.hasMoreTokens()) {
    String pathElement = st.nextToken();
    File file = new File(pathElement, path);
    if (file.isDirectory()) {
        File[] files = file.listFiles();
        for (int i = 0; i < files.length; i++) {
...

List<File> result = new ArrayList<File>();
getFilesIncludeSubdirectories(directory, result);
return result;

return files(dir).toArray(new File[0]);

File folder = new File(pathToFolder);
String[] files = folder.list(new FilenameFilter() {
    public boolean accept(File dir, String name) {
        return name.toUpperCase().endsWith(suffix.toUpperCase());
});
List<String> ret = new ArrayList<String>();
for (String file : files) {
...

if (!folder.exists()) {
    throw new FileNotFoundException();
if (!folder.isDirectory()) {
    throw new IllegalStateException(
            "execution jar is suppose to be in this folder, but the object present is not a directory: "
                    + folder);
File[] matchingFiles = folder.listFiles(new FilenameFilter() {
    @Override
    public boolean accept(File dir, String name) {
        if (name.matches(regex))
            return true;
        else
            return false;
});
if (matchingFiles == null) {
    throw new IllegalStateException(
            "the File[] matchingFiles variable is null.  This means an IOException occured while doing listFiles.  Please check disk availability and retry again");
return matchingFiles;

final Pattern pattern = Pattern.compile(regexp);
return getFilesMatchingRegexp(directory, pattern);

File file = new File(path);
return file.lastModified();

if (dir == null) {
    throw new IllegalArgumentException("argument must not be null.");
File[] files = dir.listFiles();
if (files == null) {
    throw new IllegalArgumentException("could not get files of [" + dir + "]");
return files;
...

return getFilesOfDirectory(directory, null);