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This Java library enables the FCKeditor to be used in a Servlet/J2EE environment. It provides JSP tags for creating a FCKeditor instance and a Servlet handling server-side user files and folders.

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/*
 * FCKeditor - The text editor for Internet - http://www.fckeditor.net
 * Copyright (C) 2004-2009 Frederico Caldeira Knabben
 * 
 * == BEGIN LICENSE ==
 * 
 * Licensed under the terms of any of the following licenses at your
 * choice:
 * 
 *  - GNU General Public License Version 2 or later (the "GPL")
 *    http://www.gnu.org/licenses/gpl.html
 * 
 *  - GNU Lesser General Public License Version 2.1 or later (the "LGPL")
 *    http://www.gnu.org/licenses/lgpl.html
 * 
 *  - Mozilla Public License Version 1.1 or later (the "MPL")
 *    http://www.mozilla.org/MPL/MPL-1.1.html
 * 
 * == END LICENSE ==
 */
package net.fckeditor.tool;

import java.util.HashSet;
import java.util.Set;
import java.util.StringTokenizer;

/**
 * Static helper methods for strings.
 * 
 * @version $Id: Utils.java 3832 2009-07-08 17:44:17Z mosipov $
 */
public class Utils {

	/** The empty string {@code ""}. */
	public static final String EMPTY_STRING = "";
	
	/**
	 * Constructs a set of lower-cased strings from a delimiter-separated
	 * string.
	 * 
	 * @param stringList
	 *            strings separated with a delimiter
	 * @param delimiter
	 *            separating delimiter
	 * @return a lower-cased set, empty set if stringList is empty
	 * @throws IllegalArgumentException
	 *             if delimiter is empty
	 */
	public static Set getSet(final String stringList,
			final String delimiter) {
		if (isEmpty(delimiter))
			throw new IllegalArgumentException(
					"Argument 'delimiter' shouldn't be empty!");
		if (isEmpty(stringList))
			return new HashSet();

		Set set = new HashSet();
		StringTokenizer st = new StringTokenizer(stringList, delimiter);
		while (st.hasMoreTokens()) {
			String tmp = st.nextToken();
			if (isNotEmpty(tmp)) // simple empty filter
				set.add(tmp.toLowerCase());
		}
		return set;
	}

	/**
	 * Constructs a set of lower-cased strings from a | (pipe)
	 * delimited string.
	 * 
	 * @see #getSet(String, String)
	 * @param stringList
	 *            strings separated with a delimiter
	 * @return a lower-cased set, empty set if stringList is empty
	 * @throws IllegalArgumentException
	 *             if delimiter is empty
	 */
	public static Set getSet(final String stringList) {
		return getSet(stringList, "|");
	}

	/**
	 * Checks if a string is empty ("") or null.
	 * 
	 * @param str
	 *            string to check, may be null
	 * @return true if the string is null or empty,
	 *         else false
	 */
	public static boolean isEmpty(final String str) {
		return str == null || str.length() == 0;
	}

	/**
	 * Checks if a string is not empty ("") and not null.
	 * 
	 * @param str
	 *            string to check, may be null
	 * @return true if the string is not empty and not
	 *         null, else false
	 */
	public static boolean isNotEmpty(final String str) {
		return !isEmpty(str);
	}

	/**
	 * Checks if a string is whitespace, empty ("") or null. Whitespace is
	 * checked by {@link Character#isWhitespace(char)}.
	 * 
	 * @param str
	 *            string to check, may be null
	 * @return true if the string is null, empty or
	 *         whitespace
	 */
	public static boolean isBlank(final String str) {

		if (isEmpty(str))
			return true;

		for (char c : str.toCharArray()) {
			if (!Character.isWhitespace(c))
				return false;
		}

		return true;
	}

	/**
	 * Checks if a string is not empty (""), not null and not whitespace.
	 * 
	 * @param str
	 *            string to check, may be null
	 * @return true if the string is not null, not
	 *         empty and not whitespace.
	 */
	public static boolean isNotBlank(final String str) {
		return !isBlank(str);
	}
}