Java tutorial
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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. */ /* ******************************************************************************* * (C) Copyright IBM Corp. 1996-2005 - All Rights Reserved * * * * The original version of this source code and documentation is copyrighted * * and owned by IBM, These materials are provided under terms of a License * * Agreement between IBM and Sun. This technology is protected by multiple * * US and International patents. This notice and attribution to IBM may not * * to removed. * ******************************************************************************* */ package java.text; import sun.text.normalizer.NormalizerBase; /** * This class provides the method <code>normalize</code> which transforms Unicode * text into an equivalent composed or decomposed form, allowing for easier * sorting and searching of text. * The <code>normalize</code> method supports the standard normalization forms * described in * <a href="http://www.unicode.org/unicode/reports/tr15/tr15-23.html"> * Unicode Standard Annex #15 — Unicode Normalization Forms</a>. * <p> * Characters with accents or other adornments can be encoded in * several different ways in Unicode. For example, take the character A-acute. * In Unicode, this can be encoded as a single character (the "composed" form): * * <pre> * U+00C1 LATIN CAPITAL LETTER A WITH ACUTE</pre> * * or as two separate characters (the "decomposed" form): * * <pre> * U+0041 LATIN CAPITAL LETTER A * U+0301 COMBINING ACUTE ACCENT</pre> * * To a user of your program, however, both of these sequences should be * treated as the same "user-level" character "A with acute accent". When you * are searching or comparing text, you must ensure that these two sequences are * treated as equivalent. In addition, you must handle characters with more than * one accent. Sometimes the order of a character's combining accents is * significant, while in other cases accent sequences in different orders are * really equivalent. * <p> * Similarly, the string "ffi" can be encoded as three separate letters: * * <pre> * U+0066 LATIN SMALL LETTER F * U+0066 LATIN SMALL LETTER F * U+0069 LATIN SMALL LETTER I</pre> * * or as the single character * * <pre> * U+FB03 LATIN SMALL LIGATURE FFI</pre> * * The ffi ligature is not a distinct semantic character, and strictly speaking * it shouldn't be in Unicode at all, but it was included for compatibility * with existing character sets that already provided it. The Unicode standard * identifies such characters by giving them "compatibility" decompositions * into the corresponding semantic characters. When sorting and searching, you * will often want to use these mappings. * <p> * The <code>normalize</code> method helps solve these problems by transforming * text into the canonical composed and decomposed forms as shown in the first * example above. In addition, you can have it perform compatibility * decompositions so that you can treat compatibility characters the same as * their equivalents. * Finally, the <code>normalize</code> method rearranges accents into the * proper canonical order, so that you do not have to worry about accent * rearrangement on your own. * <p> * The W3C generally recommends to exchange texts in NFC. * Note also that most legacy character encodings use only precomposed forms and * often do not encode any combining marks by themselves. For conversion to such * character encodings the Unicode text needs to be normalized to NFC. * For more usage examples, see the Unicode Standard Annex. * * @since 1.6 */ public final class Normalizer { private Normalizer() { }; /** * This enum provides constants of the four Unicode normalization forms * that are described in * <a href="http://www.unicode.org/unicode/reports/tr15/tr15-23.html"> * Unicode Standard Annex #15 — Unicode Normalization Forms</a> * and two methods to access them. * * @since 1.6 */ public static enum Form { /** * Canonical decomposition. */ NFD, /** * Canonical decomposition, followed by canonical composition. */ NFC, /** * Compatibility decomposition. */ NFKD, /** * Compatibility decomposition, followed by canonical composition. */ NFKC } /** * Normalize a sequence of char values. * The sequence will be normalized according to the specified normalization * from. * @param src The sequence of char values to normalize. * @param form The normalization form; one of * {@link java.text.Normalizer.Form#NFC}, * {@link java.text.Normalizer.Form#NFD}, * {@link java.text.Normalizer.Form#NFKC}, * {@link java.text.Normalizer.Form#NFKD} * @return The normalized String * @throws NullPointerException If <code>src</code> or <code>form</code> * is null. */ public static String normalize(CharSequence src, Form form) { return NormalizerBase.normalize(src.toString(), form); } /** * Determines if the given sequence of char values is normalized. * @param src The sequence of char values to be checked. * @param form The normalization form; one of * {@link java.text.Normalizer.Form#NFC}, * {@link java.text.Normalizer.Form#NFD}, * {@link java.text.Normalizer.Form#NFKC}, * {@link java.text.Normalizer.Form#NFKD} * @return true if the sequence of char values is normalized; * false otherwise. * @throws NullPointerException If <code>src</code> or <code>form</code> * is null. */ public static boolean isNormalized(CharSequence src, Form form) { return NormalizerBase.isNormalized(src.toString(), form); } }