1 /* EmptyAttributeSet.java -- An empty attribute set
2 Copyright (C) 2006 Free Software Foundation, Inc.
4 This file is part of GNU Classpath.
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING. If not, write to the
18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library. Thus, the terms and
23 conditions of the GNU General Public License cover the whole
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module. An independent module is a module which is not derived from
33 or based on this library. If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so. If you do not wish to do so, delete this
36 exception statement from your version. */
39 package javax.swing.text;
41 import java.util.Enumeration;
42 import java.util.NoSuchElementException;
45 * An immutable, empty attribute set.
47 * @see SimpleAttributeSet#EMPTY
49 * @author Roman Kennke (kennke@aicas.com)
51 final class EmptyAttributeSet
52 implements AttributeSet
56 * Always return false as this AttributeSet doesn't contain any attributes.
58 public boolean containsAttribute(Object name, Object value)
64 * Return true only if the attributes argument also contains no attributes.
66 public boolean containsAttributes(AttributeSet attributes)
68 return attributes.getAttributeCount() == 0;
72 * Return this, as this is immutable.
74 public AttributeSet copyAttributes()
80 * Always return null as this AttributeSet doesn't contain any attributes.
82 public Object getAttribute(Object key)
90 public int getAttributeCount()
96 * Returns an empty Enumeration.
98 public Enumeration getAttributeNames()
100 return new Enumeration()
102 public boolean hasMoreElements()
107 public Object nextElement()
109 throw new NoSuchElementException("No more elements");
116 * Always return null as this has no resolve parent.
118 public AttributeSet getResolveParent()
124 * Always return false as this AttributeSet doesn't contain any attributes.
126 public boolean isDefined(Object attrName)
132 * Other attribute sets are equal if they are empty too.
134 public boolean isEqual(AttributeSet attr)
136 return attr.getAttributeCount() == 0;
140 * Other objects are equal if it's the same instance as this, or if
141 * it's another attribute set without attributes.
143 public boolean equals(Object o)
145 boolean eq = o == this;
148 eq = (o instanceof AttributeSet)
149 && ((AttributeSet) o).getAttributeCount() == 0;