Traverse directories recursively and get the sorted URIs

Here is the utility class which can be used to traverse directories recursively and get the sorted URIs::

import java.io.File; import java.io.FileNotFoundException; import java.util.Arrays; import java.util.Iterator; import java.util.List; import java.util.Set; import java.util.TreeSet;   /** * This class DirectoryTraverser.<br/> * It returns set of files by traversing directories recursively. * * @since 2014 * @author Abhinav Kumar Mishra */ public final class DirectoryTraverser {    /**  * Gets the file URIs. Recursively traverse each directory and uris of files.  *  * @param aStartingDir the a starting dir  * @return the file listing  * @throws FileNotFoundException the file not found exception  */  public static Set<File> getFileUris(final File aStartingDir)   throws FileNotFoundException {   checkDirectories(aStartingDir); // throw exception if not valid.   return getUrisRecursive(aStartingDir);  }    /**  * Gets the file uris recursively.  *  * @param aStartingDir the a starting dir  * @return the file listing no sort  * @throws FileNotFoundException the file not found exception  */  private static Set<File> getUrisRecursive(final File aStartingDir)   throws FileNotFoundException {   final Set<File> sortedSetOfFiles = new TreeSet<File>();   final File[] filesAndDirs = aStartingDir.listFiles();   final List<File> filesDirs = Arrays.asList(filesAndDirs);   final Iterator<File> filesDirsItr = filesDirs.iterator();   while (filesDirsItr.hasNext()) {    final File file = filesDirsItr.next();    sortedSetOfFiles.add(file); // Add files and directory URIs both    // If uri is a directory the revisit it recursively.    if (!file.isFile()) {     // Call 'getUrisRecursive' to extract uris from directory     final Set<File> innerSet = getUrisRecursive(file);     sortedSetOfFiles.addAll(innerSet);    }   }   return sortedSetOfFiles;  }    /**  * Checks if is valid directory.<br/>  * If directory exists then it is valid. If directory is valid then it can  * be read.  *  * @param directoryUri the a directory  * @throws FileNotFoundException   */  private static void checkDirectories(final File directoryUri)                             throws FileNotFoundException {   if (directoryUri == null) {    throw new IllegalArgumentException("Directory should not be null.");   }if (!directoryUri.exists()) {     throw new FileNotFoundException("Directory does not exist: "+ directoryUri);   }if (!directoryUri.isDirectory()) {    throw new IllegalArgumentException("Is not a directory: "+ directoryUri);   }if (!directoryUri.canRead()) {    throw new IllegalArgumentException("Directory cannot be read: "                        + directoryUri);   }  }           public static void main(String[] args) {   try {    System.out.println(getFileUris(new File("c:\\intel")));   } catch (FileNotFoundException e) {    e.printStackTrace();   }  } }

Output>>
Let directory uri is: C:\Intel

Result:

[c:\intel\ExtremeGraphics,
c:\intel\ExtremeGraphics\CUI,
c:\intel\ExtremeGraphics\CUI\Resource,
c:\intel\Logs,
c:\intel\Logs\IntelChipset.log,
c:\intel\Logs\IntelGFX.log,
c:\intel\Logs\IntelGFXCoin.log]