code: public static String getParent(String path) {
          String parent = null;
          int lastIndex = path.lastIndexOf('/');
          if (lastIndex != -1) {
              if (path.length() == 1) {
                  parent = null;
              } else if (lastIndex == 0) {
                  parent = "/";
              } else {
                  parent = path.substring(0, lastIndex);
              }
          }
          return parent;
  
      }
docs: Answer the path with the last file name removed, using forward
  slash ('/') as the path separator character.
  
  Answer null for a path which contains no slashes.
  
  Answer null for a path which is a single slash character.
  
  Answer the path which is a single slash character when
  the path starts with a slash, which is not a single slash
  character, and which contains no other slashes.
  
  Answer the path with the trailing slash removed for
  a path which has a trailing slash and which is not a single
  slash character.
  
  Answer the the path up to but not including the trailing
  slash in all other cases.
  
  For example:
  
  For "/grandParent/parent/child" answer "/grandParent/parent".
  
  For "/grandParent/parent/" answer "/grandParent/parent".
  
  For "/parent" answer "/".
  
  For "/" answer null.
  
  For "child" answer null.
  
  For "" answer null.
  
  @param path The path with the last file named removed. An exception
  will be thrown if the path is null.
  
  @return The path with the last file name removed.