Java I/O How to - Find file on the classpath

Question

We would like to know how to find file on the classpath.
Answer

//from  ww  w  . j a  va 2  s .c  o  m
/* 
 * JCommon : a free general purpose class library for the Java(tm) platform
 * 
 *
 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
 * 
 * Project Info:  http://www.jfree.org/jcommon/index.html
 *
 * 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.]
 * 
 * ------------------
 * FileUtilities.java
 * ------------------
 * (C) Copyright 2000-2004, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * $Id: FileUtilities.java,v 1.5 2005/10/18 13:16:02 mungady Exp $
 *
 * Changes (from 5-Nov-2001)
 * -------------------------
 * 05-Nov-2001 : Changed package to com.jrefinery.io.* (DG);
 * 04-Mar-2002 : Renamed Files.java --> FileUtilities.java (DG);
 * 10-Oct-2002 : Fixed errors reported by Checkstyle (DG);
 *
 */

import java.io.File;
import java.util.StringTokenizer;

/**
 * A class containing useful utility methods relating to files.
 * 
 * @author David Gilbert
 */
public class Main {
  /**
   * Returns a reference to a file with the specified name that is located
   * somewhere on the classpath. The code for this method is an adaptation of
   * code supplied by Dave Postill.
   * 
   * @param name
   *          the filename.
   * 
   * @return a reference to a file or <code>null if no file could be
   *         found.
   */
  public static File findFileOnClassPath(final String name) {

    final String classpath = System.getProperty("java.class.path");
    final String pathSeparator = System.getProperty("path.separator");

    final StringTokenizer tokenizer = new StringTokenizer(classpath, pathSeparator);

    while (tokenizer.hasMoreTokens()) {
      final String pathElement = tokenizer.nextToken();

      final File directoryOrJar = new File(pathElement);
      final File absoluteDirectoryOrJar = directoryOrJar.getAbsoluteFile();

      if (absoluteDirectoryOrJar.isFile()) {
        final File target = new File(absoluteDirectoryOrJar.getParent(), name);
        if (target.exists()) {
          return target;
        }
      } else {
        final File target = new File(directoryOrJar, name);
        if (target.exists()) {
          return target;
        }
      }

    }
    return null;

  }

}