Parse any file name with Java and get path, name, and extension

ParseFileName.java

import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.Optional;

public class ParseFileName {

  public static void main (String[] args) {
    System.out.println(Arrays.toString(parseFileName("test").get()));
    System.out.println(Arrays.toString(parseFileName("test.a").get()));
    System.out.println(Arrays.toString(parseFileName("test.a.b").get()));
    System.out.println(Arrays.toString(parseFileName(".test").get()));
    System.out.println(Arrays.toString(parseFileName(".test.a").get()));
    System.out.println(Arrays.toString(parseFileName(".test.a.b").get()));
    System.out.println(Arrays.toString(parseFileName("a.b/.test").get()));
    System.out.println(Arrays.toString(parseFileName("a.b/.test.a").get()));
    System.out.println(Arrays.toString(parseFileName("a.b/.test.a.b").get()));
    System.out.println(Arrays.toString(parseFileName("a.b/..test").get()));
    System.out.println(Arrays.toString(parseFileName("a.b/..test..a").get()));
    System.out.println(Arrays.toString(parseFileName("a.b/..test..a..b").get()));
  }

  public static Optional<String[]> parseFileName (String fileName) {

    // if fileName is null or empty, return empty Optional
    if (fileName == null || fileName.trim().equals("")) return Optional.empty();

    // get the full path from the user-supplied file name
    // if ~ appears at the beginning of the path, replace with user's home directory
    File file = new File(fileName.trim().replaceFirst("^~",System.getProperty("user.home")));
    String canonicalPath = "";

    // try to get the canonical path of the file
    try {  canonicalPath = file.getCanonicalPath();

    } catch (SecurityException ex) {
      System.err.println("parseFileName() : SecurityException");
      return Optional.empty();

    } catch (IOException ex) {
      System.err.println("parseFileName() : IOException");
      return Optional.empty();
    }

    // all file names contain at least one slash -- get the last one
    int lastSlash = Math.max(canonicalPath.lastIndexOf('\\'), canonicalPath.lastIndexOf('/'));

    // use last slash to split path and filename -- make sure path is not an empty string
    //   otherwise, remove trailing slash from path:
    //     "C:" not "C:\" for Windows; but "/" for Linux root directory, not ""
    String pathOnly = canonicalPath.substring(0, Math.max(lastSlash, 1));
    String nameOnly = canonicalPath.substring(lastSlash+1, canonicalPath.length());
    String extnOnly = "";

    // Linux:   hidden files ("dotfiles") begin with '.'
    // Mac:     "resource fork" files begin with "._" (safe to delete / ignore)
    // Windows: temporary "lock" files begin with '~' or "~$"

    boolean dotfile = false;
    int nLeadingDots = 0;

    // if file name begins with '.', replace this dot, don't confuse with extension
    //   ex: /home/user/.gitignore    : file name is ".gitignore", no extension
    //   ex: /home/user/.thing.tar.gz : file name is ".thing", extension is ".tar.gz"

    // special treatment for "dotfiles"
    while (nameOnly.charAt(nLeadingDots) == '.')
      ++nLeadingDots;

    // check if the file has an extension (it might not)
    int dot = -1;
    if ((dot = nameOnly.indexOf('.', nLeadingDots)) > 0) {
      extnOnly = nameOnly.substring(dot+1);
      nameOnly = nameOnly.substring(0, dot);
    }

    // trim() to remove any leading / trailing spaces
    return Optional.of(new String[]{ pathOnly.trim(), nameOnly.trim(), extnOnly.trim() });

  } // end parseFileName()

}