Java tutorial
/* * =========================================================== * JFreeChart : a free chart library for the Java(tm) platform * =========================================================== * (C) Copyright 2000-2004, 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., 59 Temple Place, Suite 330, * Boston, MA 02111-1307, USA. * [Java is a trademark or registered trademark of Sun Microsystems, Inc. * in the United States and other countries.] * ------------------------ * DefaultValueDataset.java * ------------------------ * (C) Copyright 2003, 2004, by Object Refinery Limited. * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * $Id $ * Changes * ------- * 27-Mar-2003 : Version 1 (DG); * 18-Aug-2003 : Implemented Cloneable (DG); */ package org.jfree.data; import java.io.Serializable; import org.jfree.util.ObjectUtils; /** * A default implementation of the {@link ValueDataset} interface. */ public class DefaultValueDataset extends AbstractDataset implements ValueDataset, Cloneable, Serializable { /** The value. */ private Number value; /** * Constructs a new dataset, initially empty. */ public DefaultValueDataset() { this(null); } /** * Creates a new dataset. * * @param value * the value. */ public DefaultValueDataset(final double value) { this(new Double(value)); } /** * Creates a new dataset. * * @param value * the initial value. */ public DefaultValueDataset(final Number value) { this.value = value; } /** * Returns the value. * * @return the value. */ public Number getValue() { return this.value; } /** * Sets the value. A {@link DatasetChangeEvent} is sent to all registered listeners. * * @param value * the new value. */ public void setValue(final Number value) { this.value = value; notifyListeners(new DatasetChangeEvent(this, this)); } /** * Tests this dataset for equality with an arbitrary object. * * @param obj * the object. * @return A boolean. */ public boolean equals(final Object obj) { if (obj == null) { return false; } if (obj == this) { return true; } if (obj instanceof ValueDataset) { final ValueDataset vd = (ValueDataset) obj; return ObjectUtils.equal(this.value, vd.getValue()); } return false; } /** * Returns a hash code. * * @return a hash code. */ public int hashCode() { return (this.value != null ? this.value.hashCode() : 0); } }