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.] * * ----------------- * KeyedObjects.java * ----------------- * (C) Copyright 2003-2013, by Object Refinery Limited. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes: * -------- * 31-Oct-2002 : Version 1 (DG); * 11-Jan-2005 : Minor tidy up (DG); * 28-Sep-2007 : Clean up equals() method (DG); * 03-Oct-2007 : Make method behaviour consistent with DefaultKeyedValues (DG); * 03-Jul-2013 : Use ParamChecks (DG); * */ package org.jfree.data; import java.io.Serializable; import java.util.Iterator; import java.util.List; import org.jfree.chart.util.ParamChecks; import org.jfree.util.PublicCloneable; /** * A collection of (key, object) pairs. */ public class KeyedObjects implements Cloneable, PublicCloneable, Serializable { /** For serialization. */ private static final long serialVersionUID = 1321582394193530984L; /** Storage for the data. */ private List data; /** * Creates a new collection (initially empty). */ public KeyedObjects() { this.data = new java.util.ArrayList(); } /** * Returns the number of items (values) in the collection. * * @return The item count. */ public int getItemCount() { return this.data.size(); } /** * Returns an object from the list. * * @param item the item index (zero-based). * * @return The object (possibly <code>null</code>). * * @throws IndexOutOfBoundsException if <code>item</code> is out of bounds. */ public Object getObject(int item) { Object result = null; KeyedObject kobj = (KeyedObject) this.data.get(item); if (kobj != null) { result = kobj.getObject(); } return result; } /** * Returns the key at the specified position in the list. * * @param index the item index (zero-based). * * @return The row key. * * @throws IndexOutOfBoundsException if <code>item</code> is out of bounds. * * @see #getIndex(Comparable) */ public Comparable getKey(int index) { Comparable result = null; KeyedObject item = (KeyedObject) this.data.get(index); if (item != null) { result = item.getKey(); } return result; } /** * Returns the index for a given key, or <code>-1</code>. * * @param key the key (<code>null</code> not permitted). * * @return The index, or <code>-1</code> if the key is unrecognised. * * @see #getKey(int) */ public int getIndex(Comparable key) { ParamChecks.nullNotPermitted(key, "key"); int i = 0; Iterator iterator = this.data.iterator(); while (iterator.hasNext()) { KeyedObject ko = (KeyedObject) iterator.next(); if (ko.getKey().equals(key)) { return i; } i++; } return -1; } /** * Returns a list containing all the keys in the list. * * @return The keys (never <code>null</code>). */ public List getKeys() { List result = new java.util.ArrayList(); Iterator iterator = this.data.iterator(); while (iterator.hasNext()) { KeyedObject ko = (KeyedObject) iterator.next(); result.add(ko.getKey()); } return result; } /** * Returns the object for a given key. If the key is not recognised, the * method should return <code>null</code>. * * @param key the key. * * @return The object (possibly <code>null</code>). * * @see #addObject(Comparable, Object) */ public Object getObject(Comparable key) { int index = getIndex(key); if (index < 0) { throw new UnknownKeyException("The key (" + key + ") is not recognised."); } return getObject(index); } /** * Adds a new object to the collection, or overwrites an existing object. * This is the same as the {@link #setObject(Comparable, Object)} method. * * @param key the key. * @param object the object. * * @see #getObject(Comparable) */ public void addObject(Comparable key, Object object) { setObject(key, object); } /** * Replaces an existing object, or adds a new object to the collection. * This is the same as the {@link #addObject(Comparable, Object)} * method. * * @param key the key (<code>null</code> not permitted). * @param object the object. * * @see #getObject(Comparable) */ public void setObject(Comparable key, Object object) { int keyIndex = getIndex(key); if (keyIndex >= 0) { KeyedObject ko = (KeyedObject) this.data.get(keyIndex); ko.setObject(object); } else { KeyedObject ko = new KeyedObject(key, object); this.data.add(ko); } } /** * Inserts a new value at the specified position in the dataset or, if * there is an existing item with the specified key, updates the value * for that item and moves it to the specified position. * * @param position the position (in the range <code>0</code> to * <code>getItemCount()</code>). * @param key the key (<code>null</code> not permitted). * @param value the value (<code>null</code> permitted). * * @since 1.0.7 */ public void insertValue(int position, Comparable key, Object value) { if (position < 0 || position > this.data.size()) { throw new IllegalArgumentException("'position' out of bounds."); } ParamChecks.nullNotPermitted(key, "key"); int pos = getIndex(key); if (pos >= 0) { this.data.remove(pos); } KeyedObject item = new KeyedObject(key, value); if (position <= this.data.size()) { this.data.add(position, item); } else { this.data.add(item); } } /** * Removes a value from the collection. * * @param index the index of the item to remove. * * @see #removeValue(Comparable) */ public void removeValue(int index) { this.data.remove(index); } /** * Removes a value from the collection. * * @param key the key (<code>null</code> not permitted). * * @see #removeValue(int) * * @throws UnknownKeyException if the key is not recognised. */ public void removeValue(Comparable key) { // defer argument checking int index = getIndex(key); if (index < 0) { throw new UnknownKeyException("The key (" + key.toString() + ") is not recognised."); } removeValue(index); } /** * Clears all values from the collection. * * @since 1.0.7 */ public void clear() { this.data.clear(); } /** * Returns a clone of this object. Keys in the list should be immutable * and are not cloned. Objects in the list are cloned only if they * implement {@link PublicCloneable}. * * @return A clone. * * @throws CloneNotSupportedException if there is a problem cloning. */ @Override public Object clone() throws CloneNotSupportedException { KeyedObjects clone = (KeyedObjects) super.clone(); clone.data = new java.util.ArrayList(); Iterator iterator = this.data.iterator(); while (iterator.hasNext()) { KeyedObject ko = (KeyedObject) iterator.next(); clone.data.add(ko.clone()); } return clone; } /** * Tests this object for equality with an arbitrary object. * * @param obj the object (<code>null</code> permitted). * * @return A boolean. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof KeyedObjects)) { return false; } KeyedObjects that = (KeyedObjects) obj; int count = getItemCount(); if (count != that.getItemCount()) { return false; } for (int i = 0; i < count; i++) { Comparable k1 = getKey(i); Comparable k2 = that.getKey(i); if (!k1.equals(k2)) { return false; } Object o1 = getObject(i); Object o2 = that.getObject(i); if (o1 == null) { if (o2 != null) { return false; } } else { if (!o1.equals(o2)) { return false; } } } return true; } /** * Returns a hash code. * * @return A hash code. */ @Override public int hashCode() { return (this.data != null ? this.data.hashCode() : 0); } }