Checks, whether the child directory is a subdirectory of the base directory. : Path « File Input Output « Java

Checks, whether the child directory is a subdirectory of the base directory.


 * JCommon : a free general purpose class library for the Java(tm) platform
 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
 * Project Info:
 * This library is free software; you can redistribute it and/or modify it 
 * under the terms of the GNU Lesser General Public License as published by 
 * the Free Software Foundation; either version 2.1 of the License, or 
 * (at your option) any later version.
 * This library is distributed in the hope that it will be useful, but 
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
 * License for more details.
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
 * USA.  
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
 * in the United States and other countries.]
 * ------------
 * ------------
 * (C)opyright 2002-2004, by Thomas Morgner and Contributors.
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 * $Id:,v 1.8 2009/01/22 08:34:58 taqua Exp $
 * Changes
 * -------
 * 26-Jan-2003 : Initial version
 * 23-Feb-2003 : Documentation
 * 25-Feb-2003 : Fixed Checkstyle issues (DG);
 * 29-Apr-2003 : Moved to jcommon
 * 04-Jan-2004 : Fixed JDK 1.2.2 issues with createRelativeURL;
 *               added support for query strings within these urls (TM);

 * The IOUtils provide some IO related helper methods.
 * @author Thomas Morgner.
public class Main {
   * Checks, whether the child directory is a subdirectory of the base 
   * directory.
   * @param base the base directory.
   * @param child the suspected child directory.
   * @return true, if the child is a subdirectory of the base directory.
   * @throws IOException if an IOError occured during the test.
  public boolean isSubDirectory(File base, File child)
      throws IOException {
      base = base.getCanonicalFile();
      child = child.getCanonicalFile();

      File parentFile = child;
      while (parentFile != null) {
          if (base.equals(parentFile)) {
              return true;
          parentFile = parentFile.getParentFile();
      return false;


Related examples in the same category

1.Returns the path of the given resource.
2.Remove path and file information from a filename returning only its extension component
3.Absolutize a relative resource path on the given absolute base path.
4.Remove File Name SuffixRemove File Name Suffix
5.A utility class for manipulating paths
6.Strip File Extension
7.Get relative path
8.Fixes the file sperator char for the target platform using the following replacement.
9.Concatenates an array of string using a seperator.
10.Rename To Temporary Name
11.Match a path which may contain a wildcard
12.Merges the two paths to create a valid version of the second path
13.General filename and filepath manipulation utilities
14.Extract File Extension
15.Get File Name SuffixGet File Name Suffix
16.Extract the page path from the given request path
17.File name Utils
18.Convert a list of path elements to a platform-specific path.
19.Change File Name To Class NameChange File Name To Class Name
20.strip Extension name
21.Create File Name with specified white space character
22.Build a relative path to the given base path
23.Return a context-relative path, beginning with a "/", that represents the canonical version of the specified path after ".." and "." elements are resolved out.
24.Return the path within a base directory
25.Decode a path.
26.Convert a path to a cananonical form
27.Extract file name (without path and suffix) from file name with path and suffix
28.Extract file name (without path but with suffix) from file name with path and suffix
29.Build a path, but do not create it
30.Build a directory path - creating directories if neccesary
31.Collection of file path related stuff
32.Path Util
33.Get the first/last token from a path
34.Calculates the relative path between a specified root directory and a target path.
35.Get relative Path