J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1999-2004 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package javax.naming; |
| 27 | |
| 28 | import java.util.Enumeration; |
| 29 | |
| 30 | /** |
| 31 | * This interface is for enumerating lists returned by |
| 32 | * methods in the javax.naming and javax.naming.directory packages. |
| 33 | * It extends Enumeration to allow as exceptions to be thrown during |
| 34 | * the enumeration. |
| 35 | *<p> |
| 36 | * When a method such as list(), listBindings(), or search() returns |
| 37 | * a NamingEnumeration, any exceptions encountered are reserved until |
| 38 | * all results have been returned. At the end of the enumeration, the |
| 39 | * exception is thrown (by hasMore()); |
| 40 | * <p> |
| 41 | * For example, if the list() is |
| 42 | * returning only a partial answer, the corresponding exception would |
| 43 | * be PartialResultException. list() would first return a NamingEnumeration. |
| 44 | * When the last of the results has been returned by the NamingEnumeration's |
| 45 | * next(), invoking hasMore() would result in PartialResultException being thrown. |
| 46 | *<p> |
| 47 | * In another example, if a search() method was invoked with a specified |
| 48 | * size limit of 'n'. If the answer consists of more than 'n' results, |
| 49 | * search() would first return a NamingEnumeration. |
| 50 | * When the n'th result has been returned by invoking next() on the |
| 51 | * NamingEnumeration, a SizeLimitExceedException would then thrown when |
| 52 | * hasMore() is invoked. |
| 53 | *<p> |
| 54 | * Note that if the program uses hasMoreElements() and nextElement() instead |
| 55 | * to iterate through the NamingEnumeration, because these methods |
| 56 | * cannot throw exceptions, no exception will be thrown. Instead, |
| 57 | * in the previous example, after the n'th result has been returned by |
| 58 | * nextElement(), invoking hasMoreElements() would return false. |
| 59 | *<p> |
| 60 | * Note also that NoSuchElementException is thrown if the program invokes |
| 61 | * next() or nextElement() when there are no elements left in the enumeration. |
| 62 | * The program can always avoid this exception by using hasMore() and |
| 63 | * hasMoreElements() to check whether the end of the enumeration has been reached. |
| 64 | *<p> |
| 65 | * If an exception is thrown during an enumeration, |
| 66 | * the enumeration becomes invalid. |
| 67 | * Subsequent invocation of any method on that enumeration |
| 68 | * will yield undefined results. |
| 69 | * |
| 70 | * @author Rosanna Lee |
| 71 | * @author Scott Seligman |
| 72 | * |
| 73 | * @see Context#list |
| 74 | * @see Context#listBindings |
| 75 | * @see javax.naming.directory.DirContext#search |
| 76 | * @see javax.naming.directory.Attributes#getAll |
| 77 | * @see javax.naming.directory.Attributes#getIDs |
| 78 | * @see javax.naming.directory.Attribute#getAll |
| 79 | * @since 1.3 |
| 80 | */ |
| 81 | public interface NamingEnumeration<T> extends Enumeration<T> { |
| 82 | /** |
| 83 | * Retrieves the next element in the enumeration. |
| 84 | * This method allows naming exceptions encountered while |
| 85 | * retrieving the next element to be caught and handled |
| 86 | * by the application. |
| 87 | * <p> |
| 88 | * Note that <tt>next()</tt> can also throw the runtime exception |
| 89 | * NoSuchElementException to indicate that the caller is |
| 90 | * attempting to enumerate beyond the end of the enumeration. |
| 91 | * This is different from a NamingException, which indicates |
| 92 | * that there was a problem in obtaining the next element, |
| 93 | * for example, due to a referral or server unavailability, etc. |
| 94 | * |
| 95 | * @return The possibly null element in the enumeration. |
| 96 | * null is only valid for enumerations that can return |
| 97 | * null (e.g. Attribute.getAll() returns an enumeration of |
| 98 | * attribute values, and an attribute value can be null). |
| 99 | * @exception NamingException If a naming exception is encountered while attempting |
| 100 | * to retrieve the next element. See NamingException |
| 101 | * and its subclasses for the possible naming exceptions. |
| 102 | * @exception java.util.NoSuchElementException If attempting to get the next element when none is available. |
| 103 | * @see java.util.Enumeration#nextElement |
| 104 | */ |
| 105 | public T next() throws NamingException; |
| 106 | |
| 107 | /** |
| 108 | * Determines whether there are any more elements in the enumeration. |
| 109 | * This method allows naming exceptions encountered while |
| 110 | * determining whether there are more elements to be caught and handled |
| 111 | * by the application. |
| 112 | * |
| 113 | * @return true if there is more in the enumeration ; false otherwise. |
| 114 | * @exception NamingException |
| 115 | * If a naming exception is encountered while attempting |
| 116 | * to determine whether there is another element |
| 117 | * in the enumeration. See NamingException |
| 118 | * and its subclasses for the possible naming exceptions. |
| 119 | * @see java.util.Enumeration#hasMoreElements |
| 120 | */ |
| 121 | public boolean hasMore() throws NamingException; |
| 122 | |
| 123 | /** |
| 124 | * Closes this enumeration. |
| 125 | * |
| 126 | * After this method has been invoked on this enumeration, the |
| 127 | * enumeration becomes invalid and subsequent invocation of any of |
| 128 | * its methods will yield undefined results. |
| 129 | * This method is intended for aborting an enumeration to free up resources. |
| 130 | * If an enumeration proceeds to the end--that is, until |
| 131 | * <tt>hasMoreElements()</tt> or <tt>hasMore()</tt> returns <tt>false</tt>-- |
| 132 | * resources will be freed up automatically and there is no need to |
| 133 | * explicitly call <tt>close()</tt>. |
| 134 | *<p> |
| 135 | * This method indicates to the service provider that it is free |
| 136 | * to release resources associated with the enumeration, and can |
| 137 | * notify servers to cancel any outstanding requests. The <tt>close()</tt> |
| 138 | * method is a hint to implementations for managing their resources. |
| 139 | * Implementations are encouraged to use appropriate algorithms to |
| 140 | * manage their resources when client omits the <tt>close()</tt> calls. |
| 141 | * |
| 142 | * @exception NamingException If a naming exception is encountered |
| 143 | * while closing the enumeration. |
| 144 | * @since 1.3 |
| 145 | */ |
| 146 | public void close() throws NamingException; |
| 147 | } |