001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.lang3; 018 019/** 020 * <p>Operations on char primitives and Character objects.</p> 021 * 022 * <p>This class tries to handle {@code null} input gracefully. 023 * An exception will not be thrown for a {@code null} input. 024 * Each method documents its behavior in more detail.</p> 025 * 026 * <p>#ThreadSafe#</p> 027 * @since 2.1 028 */ 029public class CharUtils { 030 031 private static final String[] CHAR_STRING_ARRAY = new String[128]; 032 033 private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}; 034 035 /** 036 * Linefeed character LF ({@code '\n'}, Unicode 000a). 037 * 038 * @see <a href="http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences 039 * for Character and String Literals</a> 040 * @since 2.2 041 */ 042 public static final char LF = '\n'; 043 044 /** 045 * Carriage return characterf CR ('\r', Unicode 000d). 046 * 047 * @see <a href="http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences 048 * for Character and String Literals</a> 049 * @since 2.2 050 */ 051 public static final char CR = '\r'; 052 053 /** 054 * {@code \u0000} null control character ('\0'), abbreviated NUL. 055 * 056 * @since 3.6 057 */ 058 public static final char NUL = '\0'; 059 060 static { 061 for (char c = 0; c < CHAR_STRING_ARRAY.length; c++) { 062 CHAR_STRING_ARRAY[c] = String.valueOf(c); 063 } 064 } 065 066 /** 067 * <p>{@code CharUtils} instances should NOT be constructed in standard programming. 068 * Instead, the class should be used as {@code CharUtils.toString('c');}.</p> 069 * 070 * <p>This constructor is public to permit tools that require a JavaBean instance 071 * to operate.</p> 072 */ 073 public CharUtils() { 074 } 075 076 //----------------------------------------------------------------------- 077 /** 078 * <p>Converts the character to a Character.</p> 079 * 080 * <p>For ASCII 7 bit characters, this uses a cache that will return the 081 * same Character object each time.</p> 082 * 083 * <pre> 084 * CharUtils.toCharacterObject(' ') = ' ' 085 * CharUtils.toCharacterObject('A') = 'A' 086 * </pre> 087 * 088 * @deprecated Java 5 introduced {@link Character#valueOf(char)} which caches chars 0 through 127. 089 * @param ch the character to convert 090 * @return a Character of the specified character 091 */ 092 @Deprecated 093 public static Character toCharacterObject(final char ch) { 094 return Character.valueOf(ch); 095 } 096 097 /** 098 * <p>Converts the String to a Character using the first character, returning 099 * null for empty Strings.</p> 100 * 101 * <p>For ASCII 7 bit characters, this uses a cache that will return the 102 * same Character object each time.</p> 103 * 104 * <pre> 105 * CharUtils.toCharacterObject(null) = null 106 * CharUtils.toCharacterObject("") = null 107 * CharUtils.toCharacterObject("A") = 'A' 108 * CharUtils.toCharacterObject("BA") = 'B' 109 * </pre> 110 * 111 * @param str the character to convert 112 * @return the Character value of the first letter of the String 113 */ 114 public static Character toCharacterObject(final String str) { 115 if (StringUtils.isEmpty(str)) { 116 return null; 117 } 118 return Character.valueOf(str.charAt(0)); 119 } 120 121 //----------------------------------------------------------------------- 122 /** 123 * <p>Converts the Character to a char throwing an exception for {@code null}.</p> 124 * 125 * <pre> 126 * CharUtils.toChar(' ') = ' ' 127 * CharUtils.toChar('A') = 'A' 128 * CharUtils.toChar(null) throws IllegalArgumentException 129 * </pre> 130 * 131 * @param ch the character to convert 132 * @return the char value of the Character 133 * @throws NullPointerException if the Character is null 134 */ 135 public static char toChar(final Character ch) { 136 Validate.notNull(ch, "ch"); 137 return ch.charValue(); 138 } 139 140 /** 141 * <p>Converts the Character to a char handling {@code null}.</p> 142 * 143 * <pre> 144 * CharUtils.toChar(null, 'X') = 'X' 145 * CharUtils.toChar(' ', 'X') = ' ' 146 * CharUtils.toChar('A', 'X') = 'A' 147 * </pre> 148 * 149 * @param ch the character to convert 150 * @param defaultValue the value to use if the Character is null 151 * @return the char value of the Character or the default if null 152 */ 153 public static char toChar(final Character ch, final char defaultValue) { 154 if (ch == null) { 155 return defaultValue; 156 } 157 return ch.charValue(); 158 } 159 160 //----------------------------------------------------------------------- 161 /** 162 * <p>Converts the String to a char using the first character, throwing 163 * an exception on empty Strings.</p> 164 * 165 * <pre> 166 * CharUtils.toChar("A") = 'A' 167 * CharUtils.toChar("BA") = 'B' 168 * CharUtils.toChar(null) throws IllegalArgumentException 169 * CharUtils.toChar("") throws IllegalArgumentException 170 * </pre> 171 * 172 * @param str the character to convert 173 * @return the char value of the first letter of the String 174 * @throws NullPointerException if the string is null 175 * @throws IllegalArgumentException if the String is empty 176 */ 177 public static char toChar(final String str) { 178 Validate.notEmpty(str, "The String must not be empty"); 179 return str.charAt(0); 180 } 181 182 /** 183 * <p>Converts the String to a char using the first character, defaulting 184 * the value on empty Strings.</p> 185 * 186 * <pre> 187 * CharUtils.toChar(null, 'X') = 'X' 188 * CharUtils.toChar("", 'X') = 'X' 189 * CharUtils.toChar("A", 'X') = 'A' 190 * CharUtils.toChar("BA", 'X') = 'B' 191 * </pre> 192 * 193 * @param str the character to convert 194 * @param defaultValue the value to use if the Character is null 195 * @return the char value of the first letter of the String or the default if null 196 */ 197 public static char toChar(final String str, final char defaultValue) { 198 if (StringUtils.isEmpty(str)) { 199 return defaultValue; 200 } 201 return str.charAt(0); 202 } 203 204 //----------------------------------------------------------------------- 205 /** 206 * <p>Converts the character to the Integer it represents, throwing an 207 * exception if the character is not numeric.</p> 208 * 209 * <p>This method converts the char '1' to the int 1 and so on.</p> 210 * 211 * <pre> 212 * CharUtils.toIntValue('3') = 3 213 * CharUtils.toIntValue('A') throws IllegalArgumentException 214 * </pre> 215 * 216 * @param ch the character to convert 217 * @return the int value of the character 218 * @throws IllegalArgumentException if the character is not ASCII numeric 219 */ 220 public static int toIntValue(final char ch) { 221 if (!isAsciiNumeric(ch)) { 222 throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'"); 223 } 224 return ch - 48; 225 } 226 227 /** 228 * <p>Converts the character to the Integer it represents, throwing an 229 * exception if the character is not numeric.</p> 230 * 231 * <p>This method converts the char '1' to the int 1 and so on.</p> 232 * 233 * <pre> 234 * CharUtils.toIntValue('3', -1) = 3 235 * CharUtils.toIntValue('A', -1) = -1 236 * </pre> 237 * 238 * @param ch the character to convert 239 * @param defaultValue the default value to use if the character is not numeric 240 * @return the int value of the character 241 */ 242 public static int toIntValue(final char ch, final int defaultValue) { 243 if (!isAsciiNumeric(ch)) { 244 return defaultValue; 245 } 246 return ch - 48; 247 } 248 249 /** 250 * <p>Converts the character to the Integer it represents, throwing an 251 * exception if the character is not numeric.</p> 252 * 253 * <p>This method converts the char '1' to the int 1 and so on.</p> 254 * 255 * <pre> 256 * CharUtils.toIntValue('3') = 3 257 * CharUtils.toIntValue(null) throws IllegalArgumentException 258 * CharUtils.toIntValue('A') throws IllegalArgumentException 259 * </pre> 260 * 261 * @param ch the character to convert, not null 262 * @return the int value of the character 263 * @throws NullPointerException if the Character is null 264 * @throws IllegalArgumentException if the Character is not ASCII numeric 265 */ 266 public static int toIntValue(final Character ch) { 267 Validate.notNull(ch, "ch"); 268 return toIntValue(ch.charValue()); 269 } 270 271 /** 272 * <p>Converts the character to the Integer it represents, throwing an 273 * exception if the character is not numeric.</p> 274 * 275 * <p>This method converts the char '1' to the int 1 and so on.</p> 276 * 277 * <pre> 278 * CharUtils.toIntValue(null, -1) = -1 279 * CharUtils.toIntValue('3', -1) = 3 280 * CharUtils.toIntValue('A', -1) = -1 281 * </pre> 282 * 283 * @param ch the character to convert 284 * @param defaultValue the default value to use if the character is not numeric 285 * @return the int value of the character 286 */ 287 public static int toIntValue(final Character ch, final int defaultValue) { 288 if (ch == null) { 289 return defaultValue; 290 } 291 return toIntValue(ch.charValue(), defaultValue); 292 } 293 294 //----------------------------------------------------------------------- 295 /** 296 * <p>Converts the character to a String that contains the one character.</p> 297 * 298 * <p>For ASCII 7 bit characters, this uses a cache that will return the 299 * same String object each time.</p> 300 * 301 * <pre> 302 * CharUtils.toString(' ') = " " 303 * CharUtils.toString('A') = "A" 304 * </pre> 305 * 306 * @param ch the character to convert 307 * @return a String containing the one specified character 308 */ 309 public static String toString(final char ch) { 310 if (ch < 128) { 311 return CHAR_STRING_ARRAY[ch]; 312 } 313 return new String(new char[] {ch}); 314 } 315 316 /** 317 * <p>Converts the character to a String that contains the one character.</p> 318 * 319 * <p>For ASCII 7 bit characters, this uses a cache that will return the 320 * same String object each time.</p> 321 * 322 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 323 * 324 * <pre> 325 * CharUtils.toString(null) = null 326 * CharUtils.toString(' ') = " " 327 * CharUtils.toString('A') = "A" 328 * </pre> 329 * 330 * @param ch the character to convert 331 * @return a String containing the one specified character 332 */ 333 public static String toString(final Character ch) { 334 if (ch == null) { 335 return null; 336 } 337 return toString(ch.charValue()); 338 } 339 340 //-------------------------------------------------------------------------- 341 /** 342 * <p>Converts the string to the Unicode format '\u0020'.</p> 343 * 344 * <p>This format is the Java source code format.</p> 345 * 346 * <pre> 347 * CharUtils.unicodeEscaped(' ') = "\u0020" 348 * CharUtils.unicodeEscaped('A') = "\u0041" 349 * </pre> 350 * 351 * @param ch the character to convert 352 * @return the escaped Unicode string 353 */ 354 public static String unicodeEscaped(final char ch) { 355 return "\\u" + 356 HEX_DIGITS[(ch >> 12) & 15] + 357 HEX_DIGITS[(ch >> 8) & 15] + 358 HEX_DIGITS[(ch >> 4) & 15] + 359 HEX_DIGITS[(ch) & 15]; 360 } 361 362 /** 363 * <p>Converts the string to the Unicode format '\u0020'.</p> 364 * 365 * <p>This format is the Java source code format.</p> 366 * 367 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 368 * 369 * <pre> 370 * CharUtils.unicodeEscaped(null) = null 371 * CharUtils.unicodeEscaped(' ') = "\u0020" 372 * CharUtils.unicodeEscaped('A') = "\u0041" 373 * </pre> 374 * 375 * @param ch the character to convert, may be null 376 * @return the escaped Unicode string, null if null input 377 */ 378 public static String unicodeEscaped(final Character ch) { 379 if (ch == null) { 380 return null; 381 } 382 return unicodeEscaped(ch.charValue()); 383 } 384 385 //-------------------------------------------------------------------------- 386 /** 387 * <p>Checks whether the character is ASCII 7 bit.</p> 388 * 389 * <pre> 390 * CharUtils.isAscii('a') = true 391 * CharUtils.isAscii('A') = true 392 * CharUtils.isAscii('3') = true 393 * CharUtils.isAscii('-') = true 394 * CharUtils.isAscii('\n') = true 395 * CharUtils.isAscii('©') = false 396 * </pre> 397 * 398 * @param ch the character to check 399 * @return true if less than 128 400 */ 401 public static boolean isAscii(final char ch) { 402 return ch < 128; 403 } 404 405 /** 406 * <p>Checks whether the character is ASCII 7 bit printable.</p> 407 * 408 * <pre> 409 * CharUtils.isAsciiPrintable('a') = true 410 * CharUtils.isAsciiPrintable('A') = true 411 * CharUtils.isAsciiPrintable('3') = true 412 * CharUtils.isAsciiPrintable('-') = true 413 * CharUtils.isAsciiPrintable('\n') = false 414 * CharUtils.isAsciiPrintable('©') = false 415 * </pre> 416 * 417 * @param ch the character to check 418 * @return true if between 32 and 126 inclusive 419 */ 420 public static boolean isAsciiPrintable(final char ch) { 421 return ch >= 32 && ch < 127; 422 } 423 424 /** 425 * <p>Checks whether the character is ASCII 7 bit control.</p> 426 * 427 * <pre> 428 * CharUtils.isAsciiControl('a') = false 429 * CharUtils.isAsciiControl('A') = false 430 * CharUtils.isAsciiControl('3') = false 431 * CharUtils.isAsciiControl('-') = false 432 * CharUtils.isAsciiControl('\n') = true 433 * CharUtils.isAsciiControl('©') = false 434 * </pre> 435 * 436 * @param ch the character to check 437 * @return true if less than 32 or equals 127 438 */ 439 public static boolean isAsciiControl(final char ch) { 440 return ch < 32 || ch == 127; 441 } 442 443 /** 444 * <p>Checks whether the character is ASCII 7 bit alphabetic.</p> 445 * 446 * <pre> 447 * CharUtils.isAsciiAlpha('a') = true 448 * CharUtils.isAsciiAlpha('A') = true 449 * CharUtils.isAsciiAlpha('3') = false 450 * CharUtils.isAsciiAlpha('-') = false 451 * CharUtils.isAsciiAlpha('\n') = false 452 * CharUtils.isAsciiAlpha('©') = false 453 * </pre> 454 * 455 * @param ch the character to check 456 * @return true if between 65 and 90 or 97 and 122 inclusive 457 */ 458 public static boolean isAsciiAlpha(final char ch) { 459 return isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch); 460 } 461 462 /** 463 * <p>Checks whether the character is ASCII 7 bit alphabetic upper case.</p> 464 * 465 * <pre> 466 * CharUtils.isAsciiAlphaUpper('a') = false 467 * CharUtils.isAsciiAlphaUpper('A') = true 468 * CharUtils.isAsciiAlphaUpper('3') = false 469 * CharUtils.isAsciiAlphaUpper('-') = false 470 * CharUtils.isAsciiAlphaUpper('\n') = false 471 * CharUtils.isAsciiAlphaUpper('©') = false 472 * </pre> 473 * 474 * @param ch the character to check 475 * @return true if between 65 and 90 inclusive 476 */ 477 public static boolean isAsciiAlphaUpper(final char ch) { 478 return ch >= 'A' && ch <= 'Z'; 479 } 480 481 /** 482 * <p>Checks whether the character is ASCII 7 bit alphabetic lower case.</p> 483 * 484 * <pre> 485 * CharUtils.isAsciiAlphaLower('a') = true 486 * CharUtils.isAsciiAlphaLower('A') = false 487 * CharUtils.isAsciiAlphaLower('3') = false 488 * CharUtils.isAsciiAlphaLower('-') = false 489 * CharUtils.isAsciiAlphaLower('\n') = false 490 * CharUtils.isAsciiAlphaLower('©') = false 491 * </pre> 492 * 493 * @param ch the character to check 494 * @return true if between 97 and 122 inclusive 495 */ 496 public static boolean isAsciiAlphaLower(final char ch) { 497 return ch >= 'a' && ch <= 'z'; 498 } 499 500 /** 501 * <p>Checks whether the character is ASCII 7 bit numeric.</p> 502 * 503 * <pre> 504 * CharUtils.isAsciiNumeric('a') = false 505 * CharUtils.isAsciiNumeric('A') = false 506 * CharUtils.isAsciiNumeric('3') = true 507 * CharUtils.isAsciiNumeric('-') = false 508 * CharUtils.isAsciiNumeric('\n') = false 509 * CharUtils.isAsciiNumeric('©') = false 510 * </pre> 511 * 512 * @param ch the character to check 513 * @return true if between 48 and 57 inclusive 514 */ 515 public static boolean isAsciiNumeric(final char ch) { 516 return ch >= '0' && ch <= '9'; 517 } 518 519 /** 520 * <p>Checks whether the character is ASCII 7 bit numeric.</p> 521 * 522 * <pre> 523 * CharUtils.isAsciiAlphanumeric('a') = true 524 * CharUtils.isAsciiAlphanumeric('A') = true 525 * CharUtils.isAsciiAlphanumeric('3') = true 526 * CharUtils.isAsciiAlphanumeric('-') = false 527 * CharUtils.isAsciiAlphanumeric('\n') = false 528 * CharUtils.isAsciiAlphanumeric('©') = false 529 * </pre> 530 * 531 * @param ch the character to check 532 * @return true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive 533 */ 534 public static boolean isAsciiAlphanumeric(final char ch) { 535 return isAsciiAlpha(ch) || isAsciiNumeric(ch); 536 } 537 538 /** 539 * <p>Compares two {@code char} values numerically. This is the same functionality as provided in Java 7.</p> 540 * 541 * @param x the first {@code char} to compare 542 * @param y the second {@code char} to compare 543 * @return the value {@code 0} if {@code x == y}; 544 * a value less than {@code 0} if {@code x < y}; and 545 * a value greater than {@code 0} if {@code x > y} 546 * @since 3.4 547 */ 548 public static int compare(final char x, final char y) { 549 return x-y; 550 } 551}