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1 /* |
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2 * Copyright (c) 1994, 2005, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package java.util; |
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27 |
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28 /** |
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29 * An object that implements the Enumeration interface generates a |
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30 * series of elements, one at a time. Successive calls to the |
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31 * <code>nextElement</code> method return successive elements of the |
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32 * series. |
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33 * <p> |
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34 * For example, to print all elements of a <tt>Vector<E></tt> <i>v</i>: |
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35 * <pre> |
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36 * for (Enumeration<E> e = v.elements(); e.hasMoreElements();) |
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37 * System.out.println(e.nextElement());</pre> |
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38 * <p> |
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39 * Methods are provided to enumerate through the elements of a |
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40 * vector, the keys of a hashtable, and the values in a hashtable. |
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41 * Enumerations are also used to specify the input streams to a |
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42 * <code>SequenceInputStream</code>. |
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43 * <p> |
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44 * NOTE: The functionality of this interface is duplicated by the Iterator |
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45 * interface. In addition, Iterator adds an optional remove operation, and |
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46 * has shorter method names. New implementations should consider using |
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47 * Iterator in preference to Enumeration. |
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48 * |
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49 * @see java.util.Iterator |
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50 * @see java.io.SequenceInputStream |
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51 * @see java.util.Enumeration#nextElement() |
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52 * @see java.util.Hashtable |
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53 * @see java.util.Hashtable#elements() |
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54 * @see java.util.Hashtable#keys() |
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55 * @see java.util.Vector |
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56 * @see java.util.Vector#elements() |
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57 * |
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58 * @author Lee Boynton |
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59 * @since 1.0 |
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60 */ |
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61 public interface Enumeration<E> { |
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62 /** |
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63 * Tests if this enumeration contains more elements. |
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64 * |
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65 * @return <code>true</code> if and only if this enumeration object |
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66 * contains at least one more element to provide; |
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67 * <code>false</code> otherwise. |
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68 */ |
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69 boolean hasMoreElements(); |
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70 |
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71 /** |
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72 * Returns the next element of this enumeration if this enumeration |
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73 * object has at least one more element to provide. |
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74 * |
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75 * @return the next element of this enumeration. |
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76 * @exception NoSuchElementException if no more elements exist. |
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77 */ |
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78 E nextElement(); |
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79 } |