Java tutorial
/* * Copyright (c) 1997, 2013, 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.Enumeration; /** * A collection of unique attributes. This is a read-only, * immutable interface. An attribute is basically a key and * a value assigned to the key. The collection may represent * something like a style run, a logical style, etc. These * are generally used to describe features that will contribute * to some graphical representation such as a font. The * set of possible keys is unbounded and can be anything. * Typically View implementations will respond to attribute * definitions and render something to represent the attributes. * <p> * Attributes can potentially resolve in a hierarchy. If a * key doesn't resolve locally, and a resolving parent * exists, the key will be resolved through the parent. * * @author Timothy Prinzing * @see MutableAttributeSet */ public interface AttributeSet { /** * This interface is the type signature that is expected * to be present on any attribute key that contributes to * the determination of what font to use to render some * text. This is not considered to be a closed set, the * definition can change across version of the platform and can * be amended by additional user added entries that * correspond to logical settings that are specific to * some type of content. */ public interface FontAttribute { } /** * This interface is the type signature that is expected * to be present on any attribute key that contributes to * presentation of color. */ public interface ColorAttribute { } /** * This interface is the type signature that is expected * to be present on any attribute key that contributes to * character level presentation. This would be any attribute * that applies to a so-called <i>run</i> of * style. */ public interface CharacterAttribute { } /** * This interface is the type signature that is expected * to be present on any attribute key that contributes to * the paragraph level presentation. */ public interface ParagraphAttribute { } /** * Returns the number of attributes that are defined locally in this set. * Attributes that are defined in the parent set are not included. * * @return the number of attributes >= 0 */ public int getAttributeCount(); /** * Checks whether the named attribute has a value specified in * the set without resolving through another attribute * set. * * @param attrName the attribute name * @return true if the attribute has a value specified */ public boolean isDefined(Object attrName); /** * Determines if the two attribute sets are equivalent. * * @param attr an attribute set * @return true if the sets are equivalent */ public boolean isEqual(AttributeSet attr); /** * Returns an attribute set that is guaranteed not * to change over time. * * @return a copy of the attribute set */ public AttributeSet copyAttributes(); /** * Fetches the value of the given attribute. If the value is not found * locally, the search is continued upward through the resolving * parent (if one exists) until the value is either * found or there are no more parents. If the value is not found, * null is returned. * * @param key the non-null key of the attribute binding * @return the value of the attribute, or {@code null} if not found */ public Object getAttribute(Object key); /** * Returns an enumeration over the names of the attributes that are * defined locally in the set. Names of attributes defined in the * resolving parent, if any, are not included. The values of the * <code>Enumeration</code> may be anything and are not constrained to * a particular <code>Object</code> type. * <p> * This method never returns {@code null}. For a set with no attributes, it * returns an empty {@code Enumeration}. * * @return the names */ public Enumeration<?> getAttributeNames(); /** * Returns {@code true} if this set defines an attribute with the same * name and an equal value. If such an attribute is not found locally, * it is searched through in the resolving parent hierarchy. * * @param name the non-null attribute name * @param value the value * @return {@code true} if the set defines the attribute with an * equal value, either locally or through its resolving parent * @throws NullPointerException if either {@code name} or * {@code value} is {@code null} */ public boolean containsAttribute(Object name, Object value); /** * Returns {@code true} if this set defines all the attributes from the * given set with equal values. If an attribute is not found locally, * it is searched through in the resolving parent hierarchy. * * @param attributes the set of attributes to check against * @return {@code true} if this set defines all the attributes with equal * values, either locally or through its resolving parent * @throws NullPointerException if {@code attributes} is {@code null} */ public boolean containsAttributes(AttributeSet attributes); /** * Gets the resolving parent. * * @return the parent */ public AttributeSet getResolveParent(); /** * Attribute name used to name the collection of * attributes. */ public static final Object NameAttribute = StyleConstants.NameAttribute; /** * Attribute name used to identify the resolving parent * set of attributes, if one is defined. */ public static final Object ResolveAttribute = StyleConstants.ResolveAttribute; }