Tests two attributed strings for equality. : SimpleAttributeSet « Swing « Java Tutorial

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/* 
 * 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.]
 * 
 * ------------------------------
 * AttributedStringUtilities.java
 * ------------------------------
 * (C)opyright 2005, by Object Refinery Limited and Contributors.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * $Id: AttributedStringUtilities.java,v 1.2 2005/10/18 13:24:19 mungady Exp $
 *
 * Changes
 * -------
 * 29-Jul-2005 : Version 1(DG);
 * 
 */

import java.text.AttributedCharacterIterator;
import java.text.AttributedString;
import java.text.CharacterIterator;
import java.util.Map;

/**
 * Some utility methods for working with <code>AttributedString</code>
 * objects.
 * 
 * @author David Gilbert
 */
public class AttributedStringUtilities {

  /**
   * Tests two attributed strings for equality.
   * 
   * @param s1
   *          string 1 (<code>null</code> permitted).
   * @param s2
   *          string 2 (<code>null</code> permitted).
   * 
   * @return <code>true</code> if <code>s1</code> and <code>s2</code> are
   *         equal or both <code>null</code>, and <code>false</code>
   *         otherwise.
   */
  public static boolean equal(AttributedString s1, AttributedString s2) {
    if (s1 == null) {
      return (s2 == null);
    }
    if (s2 == null) {
      return false;
    }
    AttributedCharacterIterator it1 = s1.getIterator();
    AttributedCharacterIterator it2 = s2.getIterator();
    char c1 = it1.first();
    char c2 = it2.first();
    int start = 0;
    while (c1 != CharacterIterator.DONE) {
      int limit1 = it1.getRunLimit();
      int limit2 = it2.getRunLimit();
      if (limit1 != limit2) {
        return false;
      }
      // if maps aren't equivalent, return false
      Map m1 = it1.getAttributes();
      Map m2 = it2.getAttributes();
      if (!m1.equals(m2)) {
        return false;
      }
      // now check characters in the run are the same
      for (int i = start; i < limit1; i++) {
        if (c1 != c2) {
          return false;
        }
        c1 = it1.next();
        c2 = it2.next();
      }
      start = limit1;
    }
    return c2 == CharacterIterator.DONE;
  }

}