Null.java |
/*************************************** * * * JBoss: The OpenSource J2EE WebOS * * * * Distributable under LGPL license. * * See terms of license at gnu.org. * * * ***************************************/ package org.jboss.util; import java.io.Serializable; /** * A class that represents <tt>null</tt>. * * <p>{@link Null#VALUE} is used to given an object variable a dual-mode * nullified value, where <tt>null</tt> would indicate that the value is * empty, and {@link Null#VALUE} would idicate that the value has been * set to <tt>null</tt> (or something to that effect). * * @version <tt>$Revision: 1.1.28.1 $</tt> * @author <a href="mailto:jason@planet57.com">Jason Dillon</a> */ public final class Null implements Serializable { static final long serialVersionUID = -403173436435490144L; /** The primary instance of Null. */ public static final Null VALUE = new Null(); /** Do not allow public construction. */ private Null() {} /** * Return a string representation. * * @return Null */ public String toString() { return null; } /** * Returns zero. * * @return Zero. */ public int hashCode() { return 0; } /** * Check if the given object is a Null instance or <tt>null</tt>. * * @param obj Object to test. * @return True if the given object is a Null instance or <tt>null</tt>. */ public boolean equals(final Object obj) { if (obj == this) return true; return (obj == null || obj.getClass() == getClass()); } }
Null.java |