Java tutorial
/* =========================================================== * JFreeChart : a free chart library for the Java(tm) platform * =========================================================== * * (C) Copyright 2000-2014, 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.] * * --------------------- * ObjectUtilitiess.java * --------------------- * (C) Copyright 2003-2014, by Object Refinery Limited. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes * ------- * 25-Mar-2003 : Version 1 (DG); * 15-Sep-2003 : Fixed bug in clone(List) method (DG); * 25-Nov-2004 : Modified clone(Object) method to fail with objects that * cannot be cloned, added new deepClone(Collection) method. * Renamed ObjectUtils --> ObjectUtils (DG); * 11-Jan-2005 : Removed deprecated code in preparation for 1.0.0 release (DG); * 18-Aug-2005 : Added casts to suppress compiler warnings, as suggested in * patch 1260622 (DG); * 16-Jun-2012 : Moved from JCommon to JFreeChart (DG); * */ package org.jfree.chart.util; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import java.util.Collection; /** * A collection of useful static utility methods for handling classes and object * instantiation. */ public final class ObjectUtils { /** * Default constructor - private. */ private ObjectUtils() { } /** * Returns <code>true</code> if the two objects are equal OR both * <code>null</code>. * * @param o1 object 1 (<code>null</code> permitted). * @param o2 object 2 (<code>null</code> permitted). * @return <code>true</code> or <code>false</code>. */ public static boolean equal(final Object o1, final Object o2) { if (o1 == o2) { return true; } if (o1 != null) { return o1.equals(o2); } else { return false; } } /** * Returns a hash code for an object, or zero if the object is * <code>null</code>. * * @param object the object (<code>null</code> permitted). * @return The object's hash code (or zero if the object is * <code>null</code>). */ public static int hashCode(final Object object) { int result = 0; if (object != null) { result = object.hashCode(); } return result; } /** * Returns a clone of the specified object, if it can be cloned, otherwise * throws a CloneNotSupportedException. * * @param <T> The object type. * @param object the object to clone (<code>null</code> not permitted). * @return A clone of the specified object. * @throws CloneNotSupportedException if the object cannot be cloned. */ public static <T> T clone(T object) throws CloneNotSupportedException { if (object == null) { throw new IllegalArgumentException("Null 'object' argument."); } if (object instanceof PublicCloneable) { PublicCloneable pc = (PublicCloneable) object; return (T) pc.clone(); } else { try { Method method = object.getClass().getMethod("clone"); if (Modifier.isPublic(method.getModifiers())) { return (T) method.invoke(object); } } catch (NoSuchMethodException e) { //Log.warn("Object without clone() method is impossible."); throw new CloneNotSupportedException(e.getMessage()); } catch (IllegalAccessException e) { //Log.warn("Object.clone(): unable to call method."); throw new CloneNotSupportedException(e.getMessage()); } catch (InvocationTargetException e) { //Log.warn("Object without clone() method is impossible."); throw new CloneNotSupportedException(e.getMessage()); } } throw new CloneNotSupportedException("Failed to clone."); } /** * Returns a new collection containing clones of all the items in the * specified collection. * * @param <T> The object type. * @param <C> The collection type. * @param collection the collection (<code>null</code> not permitted). * @return A new collection containing clones of all the items in the * specified collection. * @throws CloneNotSupportedException if any of the items in the collection * cannot be cloned. */ public static <T, C extends Collection<T>> C deepClone(final C collection) throws CloneNotSupportedException { if (collection == null) { throw new IllegalArgumentException("Null 'collection' argument."); } // all JDK-Collections are cloneable ... // and if the collection is not clonable, then we should throw // a CloneNotSupportedException anyway ... final C result = ObjectUtils.clone(collection); result.clear(); for (T item : collection) { if (item == null) { result.add(null); } else { result.add(clone(item)); } } return result; } }