Java tutorial
/* * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.security; import javax.security.auth.Subject; /** * This interface represents the abstract notion of a principal, which * can be used to represent any entity, such as an individual, a * corporation, and a login id. * * @see java.security.cert.X509Certificate * * @author Li Gong * @since 1.1 */ public interface Principal { /** * Compares this principal to the specified object. Returns true * if the object passed in matches the principal represented by * the implementation of this interface. * * @param another principal to compare with. * * @return true if the principal passed in is the same as that * encapsulated by this principal, and false otherwise. */ public boolean equals(Object another); /** * Returns a string representation of this principal. * * @return a string representation of this principal. */ public String toString(); /** * Returns a hashcode for this principal. * * @return a hashcode for this principal. */ public int hashCode(); /** * Returns the name of this principal. * * @return the name of this principal. */ public String getName(); /** * Returns true if the specified subject is implied by this principal. * * @implSpec * The default implementation of this method returns true if * {@code subject} is non-null and contains at least one principal that * is equal to this principal. * * <p>Subclasses may override this with a different implementation, if * necessary. * * @param subject the {@code Subject} * @return true if {@code subject} is non-null and is * implied by this principal, or false otherwise. * @since 1.8 */ public default boolean implies(Subject subject) { if (subject == null) return false; return subject.getPrincipals().contains(this); } }