Method simplifyPath

guava/src/com/google/common/io/Files.java:733–777

Returns the lexically cleaned form of the path name, <i>usually</i> (but not always) equivalent to the original. The following heuristics are used: <ul> <li>empty string becomes . <li>. stays as . <li>fold out ./ <li>fold out ../ when possible <li>collapse multiple slashes <li>delete tr

(String pathname)

   * @since 11.0
   */
  public static String simplifyPath(String pathname) {
    checkNotNull(pathname);
    if (pathname.isEmpty()) {
      return ".";
    }

    // split the path apart
    Iterable<String> components = Splitter.on('/').omitEmptyStrings().split(pathname);
    List<String> path = new ArrayList<>();

    // resolve ., .., and //
    for (String component : components) {
      switch (component) {
        case ".":
          continue;
        case "..":
          if (path.size() > 0 && !path.get(path.size() - 1).equals("..")) {
            path.remove(path.size() - 1);
          } else {
            path.add("..");
          }
          break;
        default:
          path.add(component);
          break;
      }
    }

    // put it back together
    String result = Joiner.on('/').join(path);
    if (pathname.charAt(0) == '/') {
      result = "/" + result;
    }

    while (result.startsWith("/../")) {
      result = result.substring(3);
    }
    if (result.equals("/..")) {
      result = "/";
    } else if (result.isEmpty()) {
      result = ".";
    }

    return result;
  }

  /**
   * Returns the <a href="http://en.wikipedia.org/wiki/Filename_extension">file extension</a> for