Java tutorial
/* =========================================================== * JFreeChart : a free chart library for the Java(tm) platform * =========================================================== * * (C) Copyright 2000-2013, by Object Refinery Limited and Contributors. * * Project Info: http://www.jfree.org/jfreechart/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. * * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. * Other names may be trademarks of their respective owners.] * * ------------------ * KeyToGroupMap.java * ------------------ * (C) Copyright 2004-2013, by Object Refinery Limited and Contributors. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes * ------- * 29-Apr-2004 : Version 1 (DG); * 07-Jul-2004 : Added a group list to ensure group index is consistent, fixed * cloning problem (DG); * 18-Aug-2005 : Added casts in clone() method to suppress 1.5 compiler * warnings - see patch 1260587 (DG); * 03-Jul-2013 : Use ParamChecks (DG); * */ package org.jfree.data; import java.io.Serializable; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import org.jfree.chart.util.ParamChecks; import org.jfree.util.ObjectUtilities; import org.jfree.util.PublicCloneable; /** * A class that maps keys (instances of <code>Comparable</code>) to groups. */ public class KeyToGroupMap implements Cloneable, PublicCloneable, Serializable { /** For serialization. */ private static final long serialVersionUID = -2228169345475318082L; /** The default group. */ private Comparable defaultGroup; /** The groups. */ private List groups; /** A mapping between keys and groups. */ private Map keyToGroupMap; /** * Creates a new map with a default group named 'Default Group'. */ public KeyToGroupMap() { this("Default Group"); } /** * Creates a new map with the specified default group. * * @param defaultGroup the default group (<code>null</code> not permitted). */ public KeyToGroupMap(Comparable defaultGroup) { ParamChecks.nullNotPermitted(defaultGroup, "defaultGroup"); this.defaultGroup = defaultGroup; this.groups = new ArrayList(); this.keyToGroupMap = new HashMap(); } /** * Returns the number of groups in the map. * * @return The number of groups in the map. */ public int getGroupCount() { return this.groups.size() + 1; } /** * Returns a list of the groups (always including the default group) in the * map. The returned list is independent of the map, so altering the list * will have no effect. * * @return The groups (never <code>null</code>). */ public List getGroups() { List result = new ArrayList(); result.add(this.defaultGroup); Iterator iterator = this.groups.iterator(); while (iterator.hasNext()) { Comparable group = (Comparable) iterator.next(); if (!result.contains(group)) { result.add(group); } } return result; } /** * Returns the index for the group. * * @param group the group. * * @return The group index (or -1 if the group is not represented within * the map). */ public int getGroupIndex(Comparable group) { int result = this.groups.indexOf(group); if (result < 0) { if (this.defaultGroup.equals(group)) { result = 0; } } else { result = result + 1; } return result; } /** * Returns the group that a key is mapped to. * * @param key the key (<code>null</code> not permitted). * * @return The group (never <code>null</code>, returns the default group if * there is no mapping for the specified key). */ public Comparable getGroup(Comparable key) { ParamChecks.nullNotPermitted(key, "key"); Comparable result = this.defaultGroup; Comparable group = (Comparable) this.keyToGroupMap.get(key); if (group != null) { result = group; } return result; } /** * Maps a key to a group. * * @param key the key (<code>null</code> not permitted). * @param group the group (<code>null</code> permitted, clears any * existing mapping). */ public void mapKeyToGroup(Comparable key, Comparable group) { ParamChecks.nullNotPermitted(key, "key"); Comparable currentGroup = getGroup(key); if (!currentGroup.equals(this.defaultGroup)) { if (!currentGroup.equals(group)) { int count = getKeyCount(currentGroup); if (count == 1) { this.groups.remove(currentGroup); } } } if (group == null) { this.keyToGroupMap.remove(key); } else { if (!this.groups.contains(group)) { if (!this.defaultGroup.equals(group)) { this.groups.add(group); } } this.keyToGroupMap.put(key, group); } } /** * Returns the number of keys mapped to the specified group. This method * won't always return an accurate result for the default group, since * explicit mappings are not required for this group. * * @param group the group (<code>null</code> not permitted). * * @return The key count. */ public int getKeyCount(Comparable group) { ParamChecks.nullNotPermitted(group, "group"); int result = 0; Iterator iterator = this.keyToGroupMap.values().iterator(); while (iterator.hasNext()) { Comparable g = (Comparable) iterator.next(); if (group.equals(g)) { result++; } } return result; } /** * Tests the map for equality against an arbitrary object. * * @param obj the object to test against (<code>null</code> permitted). * * @return A boolean. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof KeyToGroupMap)) { return false; } KeyToGroupMap that = (KeyToGroupMap) obj; if (!ObjectUtilities.equal(this.defaultGroup, that.defaultGroup)) { return false; } if (!this.keyToGroupMap.equals(that.keyToGroupMap)) { return false; } return true; } /** * Returns a clone of the map. * * @return A clone. * * @throws CloneNotSupportedException if there is a problem cloning the * map. */ @Override public Object clone() throws CloneNotSupportedException { KeyToGroupMap result = (KeyToGroupMap) super.clone(); result.defaultGroup = (Comparable) KeyToGroupMap.clone(this.defaultGroup); result.groups = (List) KeyToGroupMap.clone(this.groups); result.keyToGroupMap = (Map) KeyToGroupMap.clone(this.keyToGroupMap); return result; } /** * Attempts to clone the specified object using reflection. * * @param object the object (<code>null</code> permitted). * * @return The cloned object, or the original object if cloning failed. */ private static Object clone(Object object) { if (object == null) { return null; } Class c = object.getClass(); Object result = null; try { Method m = c.getMethod("clone", (Class[]) null); if (Modifier.isPublic(m.getModifiers())) { try { result = m.invoke(object, (Object[]) null); } catch (Exception e) { e.printStackTrace(); } } } catch (NoSuchMethodException e) { result = object; } return result; } /** * Returns a clone of the list. * * @param list the list. * * @return A clone of the list. * * @throws CloneNotSupportedException if the list could not be cloned. */ private static Collection clone(Collection list) throws CloneNotSupportedException { Collection result = null; if (list != null) { try { List clone = (List) list.getClass().newInstance(); Iterator iterator = list.iterator(); while (iterator.hasNext()) { clone.add(KeyToGroupMap.clone(iterator.next())); } result = clone; } catch (Exception e) { throw new CloneNotSupportedException("Exception."); } } return result; } }