| /* |
| * Copyright (c) 1997, 2019, 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. |
| * |
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| |
| /* |
| * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved |
| * (C) Copyright IBM Corp. 1996 - All Rights Reserved |
| * |
| * The original version of this source code and documentation is copyrighted |
| * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These |
| * materials are provided under terms of a License Agreement between Taligent |
| * and Sun. This technology is protected by multiple US and International |
| * patents. This notice and attribution to Taligent may not be removed. |
| * Taligent is a registered trademark of Taligent, Inc. |
| * |
| */ |
| |
| package java.text; |
| |
| /** |
| * A {@code CollationKey} represents a {@code String} under the |
| * rules of a specific {@code Collator} object. Comparing two |
| * {@code CollationKey}s returns the relative order of the |
| * {@code String}s they represent. Using {@code CollationKey}s |
| * to compare {@code String}s is generally faster than using |
| * {@code Collator.compare}. Thus, when the {@code String}s |
| * must be compared multiple times, for example when sorting a list |
| * of {@code String}s. It's more efficient to use {@code CollationKey}s. |
| * |
| * <p> |
| * You can not create {@code CollationKey}s directly. Rather, |
| * generate them by calling {@code Collator.getCollationKey}. |
| * You can only compare {@code CollationKey}s generated from |
| * the same {@code Collator} object. |
| * |
| * <p> |
| * Generating a {@code CollationKey} for a {@code String} |
| * involves examining the entire {@code String} |
| * and converting it to series of bits that can be compared bitwise. This |
| * allows fast comparisons once the keys are generated. The cost of generating |
| * keys is recouped in faster comparisons when {@code String}s need |
| * to be compared many times. On the other hand, the result of a comparison |
| * is often determined by the first couple of characters of each {@code String}. |
| * {@code Collator.compare} examines only as many characters as it needs which |
| * allows it to be faster when doing single comparisons. |
| * <p> |
| * The following example shows how {@code CollationKey}s might be used |
| * to sort a list of {@code String}s. |
| * <blockquote> |
| * <pre>{@code |
| * // Create an array of CollationKeys for the Strings to be sorted. |
| * Collator myCollator = Collator.getInstance(); |
| * CollationKey[] keys = new CollationKey[3]; |
| * keys[0] = myCollator.getCollationKey("Tom"); |
| * keys[1] = myCollator.getCollationKey("Dick"); |
| * keys[2] = myCollator.getCollationKey("Harry"); |
| * sort(keys); |
| * |
| * //... |
| * |
| * // Inside body of sort routine, compare keys this way |
| * if (keys[i].compareTo(keys[j]) > 0) |
| * // swap keys[i] and keys[j] |
| * |
| * //... |
| * |
| * // Finally, when we've returned from sort. |
| * System.out.println(keys[0].getSourceString()); |
| * System.out.println(keys[1].getSourceString()); |
| * System.out.println(keys[2].getSourceString()); |
| * }</pre> |
| * </blockquote> |
| * |
| * @see Collator |
| * @see RuleBasedCollator |
| * @author Helena Shih |
| * @since 1.1 |
| */ |
| |
| public abstract class CollationKey implements Comparable<CollationKey> { |
| /** |
| * Compare this CollationKey to the target CollationKey. The collation rules of the |
| * Collator object which created these keys are applied. <strong>Note:</strong> |
| * CollationKeys created by different Collators can not be compared. |
| * @param target target CollationKey |
| * @return Returns an integer value. Value is less than zero if this is less |
| * than target, value is zero if this and target are equal and value is greater than |
| * zero if this is greater than target. |
| * @see java.text.Collator#compare |
| */ |
| public abstract int compareTo(CollationKey target); |
| |
| /** |
| * Returns the String that this CollationKey represents. |
| * |
| * @return the source string of this CollationKey |
| */ |
| public String getSourceString() { |
| return source; |
| } |
| |
| |
| /** |
| * Converts the CollationKey to a sequence of bits. If two CollationKeys |
| * could be legitimately compared, then one could compare the byte arrays |
| * for each of those keys to obtain the same result. Byte arrays are |
| * organized most significant byte first. |
| * |
| * @return a byte array representation of the CollationKey |
| */ |
| public abstract byte[] toByteArray(); |
| |
| |
| /** |
| * CollationKey constructor. |
| * |
| * @param source the source string |
| * @throws NullPointerException if {@code source} is null |
| * @since 1.6 |
| */ |
| protected CollationKey(String source) { |
| if (source==null){ |
| throw new NullPointerException(); |
| } |
| this.source = source; |
| } |
| |
| private final String source; |
| } |