Java tutorial
/* * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing.text; import java.util.Hashtable; import java.util.Enumeration; import java.util.Collections; import java.io.IOException; import java.io.ObjectInputStream; import java.io.Serializable; import java.util.AbstractMap; import java.util.LinkedHashMap; /** * A straightforward implementation of MutableAttributeSet using a * hash table. * <p> * <strong>Warning:</strong> * Serialized objects of this class will not be compatible with * future Swing releases. The current serialization support is * appropriate for short term storage or RMI between applications running * the same version of Swing. As of 1.4, support for long term storage * of all JavaBeans™ * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. * * @author Tim Prinzing */ @SuppressWarnings("serial") // Same-version serialization only public class SimpleAttributeSet implements MutableAttributeSet, Serializable, Cloneable { private static final long serialVersionUID = -6631553454711782652L; /** * An empty attribute set. */ public static final AttributeSet EMPTY = new EmptyAttributeSet(); private transient LinkedHashMap<Object, Object> table = new LinkedHashMap<>(3); /** * Creates a new attribute set. */ public SimpleAttributeSet() { } /** * Creates a new attribute set based on a supplied set of attributes. * * @param source the set of attributes */ public SimpleAttributeSet(AttributeSet source) { addAttributes(source); } /** * Checks whether the set of attributes is empty. * * @return true if the set is empty else false */ public boolean isEmpty() { return table.isEmpty(); } /** * Gets a count of the number of attributes. * * @return the count */ public int getAttributeCount() { return table.size(); } /** * Tells whether a given attribute is defined. * * @param attrName the attribute name * @return true if the attribute is defined */ public boolean isDefined(Object attrName) { return table.containsKey(attrName); } /** * Compares two attribute sets. * * @param attr the second attribute set * @return true if the sets are equal, false otherwise */ public boolean isEqual(AttributeSet attr) { return ((getAttributeCount() == attr.getAttributeCount()) && containsAttributes(attr)); } /** * Makes a copy of the attributes. * * @return the copy */ public AttributeSet copyAttributes() { return (AttributeSet) clone(); } /** * Gets the names of the attributes in the set. * * @return the names as an <code>Enumeration</code> */ public Enumeration<?> getAttributeNames() { return Collections.enumeration(table.keySet()); } /** * Gets the value of an attribute. * * @param name the attribute name * @return the value */ public Object getAttribute(Object name) { Object value = table.get(name); if (value == null) { AttributeSet parent = getResolveParent(); if (parent != null) { value = parent.getAttribute(name); } } return value; } /** * Checks whether the attribute list contains a * specified attribute name/value pair. * * @param name the name * @param value the value * @return true if the name/value pair is in the list */ public boolean containsAttribute(Object name, Object value) { return value.equals(getAttribute(name)); } /** * Checks whether the attribute list contains all the * specified name/value pairs. * * @param attributes the attribute list * @return true if the list contains all the name/value pairs */ public boolean containsAttributes(AttributeSet attributes) { boolean result = true; Enumeration<?> names = attributes.getAttributeNames(); while (result && names.hasMoreElements()) { Object name = names.nextElement(); result = attributes.getAttribute(name).equals(getAttribute(name)); } return result; } /** * Adds an attribute to the list. * * @param name the attribute name * @param value the attribute value */ public void addAttribute(Object name, Object value) { table.put(name, value); } /** * Adds a set of attributes to the list. * * @param attributes the set of attributes to add */ public void addAttributes(AttributeSet attributes) { Enumeration<?> names = attributes.getAttributeNames(); while (names.hasMoreElements()) { Object name = names.nextElement(); addAttribute(name, attributes.getAttribute(name)); } } /** * Removes an attribute from the list. * * @param name the attribute name */ public void removeAttribute(Object name) { table.remove(name); } /** * Removes a set of attributes from the list. * * @param names the set of names to remove */ public void removeAttributes(Enumeration<?> names) { while (names.hasMoreElements()) removeAttribute(names.nextElement()); } /** * Removes a set of attributes from the list. * * @param attributes the set of attributes to remove */ public void removeAttributes(AttributeSet attributes) { if (attributes == this) { table.clear(); } else { Enumeration<?> names = attributes.getAttributeNames(); while (names.hasMoreElements()) { Object name = names.nextElement(); Object value = attributes.getAttribute(name); if (value.equals(getAttribute(name))) removeAttribute(name); } } } /** * Gets the resolving parent. This is the set * of attributes to resolve through if an attribute * isn't defined locally. This is null if there * are no other sets of attributes to resolve * through. * * @return the parent */ public AttributeSet getResolveParent() { return (AttributeSet) table.get(StyleConstants.ResolveAttribute); } /** * Sets the resolving parent. * * @param parent the parent */ public void setResolveParent(AttributeSet parent) { addAttribute(StyleConstants.ResolveAttribute, parent); } // --- Object methods --------------------------------- /** * Clones a set of attributes. * * @return the new set of attributes */ @SuppressWarnings("unchecked") // Cast of result of clone public Object clone() { SimpleAttributeSet attr; try { attr = (SimpleAttributeSet) super.clone(); attr.table = (LinkedHashMap) table.clone(); } catch (CloneNotSupportedException cnse) { attr = null; } return attr; } /** * Returns a hashcode for this set of attributes. * @return a hashcode value for this set of attributes. */ public int hashCode() { return table.hashCode(); } /** * Compares this object to the specified object. * The result is <code>true</code> if the object is an equivalent * set of attributes. * @param obj the object to compare this attribute set with * @return <code>true</code> if the objects are equal; * <code>false</code> otherwise */ public boolean equals(Object obj) { if (this == obj) { return true; } if (obj instanceof AttributeSet) { AttributeSet attrs = (AttributeSet) obj; return isEqual(attrs); } return false; } /** * Converts the attribute set to a String. * * @return the string */ public String toString() { String s = ""; Enumeration<?> names = getAttributeNames(); while (names.hasMoreElements()) { Object key = names.nextElement(); Object value = getAttribute(key); if (value instanceof AttributeSet) { // don't go recursive s = s + key + "=**AttributeSet** "; } else { s = s + key + "=" + value + " "; } } return s; } private void writeObject(java.io.ObjectOutputStream s) throws IOException { s.defaultWriteObject(); StyleContext.writeAttributeSet(s, this); } private void readObject(ObjectInputStream s) throws ClassNotFoundException, IOException { s.defaultReadObject(); table = new LinkedHashMap<>(3); StyleContext.readAttributeSet(s, this); } /** * An AttributeSet that is always empty. */ static class EmptyAttributeSet implements AttributeSet, Serializable { static final long serialVersionUID = -8714803568785904228L; public int getAttributeCount() { return 0; } public boolean isDefined(Object attrName) { return false; } public boolean isEqual(AttributeSet attr) { return (attr.getAttributeCount() == 0); } public AttributeSet copyAttributes() { return this; } public Object getAttribute(Object key) { return null; } public Enumeration<?> getAttributeNames() { return Collections.emptyEnumeration(); } public boolean containsAttribute(Object name, Object value) { return false; } public boolean containsAttributes(AttributeSet attributes) { return (attributes.getAttributeCount() == 0); } public AttributeSet getResolveParent() { return null; } public boolean equals(Object obj) { if (this == obj) { return true; } return ((obj instanceof AttributeSet) && (((AttributeSet) obj).getAttributeCount() == 0)); } public int hashCode() { return 0; } } }