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 behaviour 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 super(); 075 } 076 077 //----------------------------------------------------------------------- 078 /** 079 * <p>Converts the character to a Character.</p> 080 * 081 * <p>For ASCII 7 bit characters, this uses a cache that will return the 082 * same Character object each time.</p> 083 * 084 * <pre> 085 * CharUtils.toCharacterObject(' ') = ' ' 086 * CharUtils.toCharacterObject('A') = 'A' 087 * </pre> 088 * 089 * @deprecated Java 5 introduced {@link Character#valueOf(char)} which caches chars 0 through 127. 090 * @param ch the character to convert 091 * @return a Character of the specified character 092 */ 093 @Deprecated 094 public static Character toCharacterObject(final char ch) { 095 return Character.valueOf(ch); 096 } 097 098 /** 099 * <p>Converts the String to a Character using the first character, returning 100 * null for empty Strings.</p> 101 * 102 * <p>For ASCII 7 bit characters, this uses a cache that will return the 103 * same Character object each time.</p> 104 * 105 * <pre> 106 * CharUtils.toCharacterObject(null) = null 107 * CharUtils.toCharacterObject("") = null 108 * CharUtils.toCharacterObject("A") = 'A' 109 * CharUtils.toCharacterObject("BA") = 'B' 110 * </pre> 111 * 112 * @param str the character to convert 113 * @return the Character value of the first letter of the String 114 */ 115 public static Character toCharacterObject(final String str) { 116 if (StringUtils.isEmpty(str)) { 117 return null; 118 } 119 return Character.valueOf(str.charAt(0)); 120 } 121 122 //----------------------------------------------------------------------- 123 /** 124 * <p>Converts the Character to a char throwing an exception for {@code null}.</p> 125 * 126 * <pre> 127 * CharUtils.toChar(' ') = ' ' 128 * CharUtils.toChar('A') = 'A' 129 * CharUtils.toChar(null) throws IllegalArgumentException 130 * </pre> 131 * 132 * @param ch the character to convert 133 * @return the char value of the Character 134 * @throws IllegalArgumentException if the Character is null 135 */ 136 public static char toChar(final Character ch) { 137 Validate.notNull(ch, "The Character must not be null"); 138 return ch.charValue(); 139 } 140 141 /** 142 * <p>Converts the Character to a char handling {@code null}.</p> 143 * 144 * <pre> 145 * CharUtils.toChar(null, 'X') = 'X' 146 * CharUtils.toChar(' ', 'X') = ' ' 147 * CharUtils.toChar('A', 'X') = 'A' 148 * </pre> 149 * 150 * @param ch the character to convert 151 * @param defaultValue the value to use if the Character is null 152 * @return the char value of the Character or the default if null 153 */ 154 public static char toChar(final Character ch, final char defaultValue) { 155 if (ch == null) { 156 return defaultValue; 157 } 158 return ch.charValue(); 159 } 160 161 //----------------------------------------------------------------------- 162 /** 163 * <p>Converts the String to a char using the first character, throwing 164 * an exception on empty Strings.</p> 165 * 166 * <pre> 167 * CharUtils.toChar("A") = 'A' 168 * CharUtils.toChar("BA") = 'B' 169 * CharUtils.toChar(null) throws IllegalArgumentException 170 * CharUtils.toChar("") throws IllegalArgumentException 171 * </pre> 172 * 173 * @param str the character to convert 174 * @return the char value of the first letter of the String 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 IllegalArgumentException if the Character is not ASCII numeric or is null 264 */ 265 public static int toIntValue(final Character ch) { 266 Validate.notNull(ch, "The character must not be null"); 267 return toIntValue(ch.charValue()); 268 } 269 270 /** 271 * <p>Converts the character to the Integer it represents, throwing an 272 * exception if the character is not numeric.</p> 273 * 274 * <p>This method converts the char '1' to the int 1 and so on.</p> 275 * 276 * <pre> 277 * CharUtils.toIntValue(null, -1) = -1 278 * CharUtils.toIntValue('3', -1) = 3 279 * CharUtils.toIntValue('A', -1) = -1 280 * </pre> 281 * 282 * @param ch the character to convert 283 * @param defaultValue the default value to use if the character is not numeric 284 * @return the int value of the character 285 */ 286 public static int toIntValue(final Character ch, final int defaultValue) { 287 if (ch == null) { 288 return defaultValue; 289 } 290 return toIntValue(ch.charValue(), defaultValue); 291 } 292 293 //----------------------------------------------------------------------- 294 /** 295 * <p>Converts the character to a String that contains the one character.</p> 296 * 297 * <p>For ASCII 7 bit characters, this uses a cache that will return the 298 * same String object each time.</p> 299 * 300 * <pre> 301 * CharUtils.toString(' ') = " " 302 * CharUtils.toString('A') = "A" 303 * </pre> 304 * 305 * @param ch the character to convert 306 * @return a String containing the one specified character 307 */ 308 public static String toString(final char ch) { 309 if (ch < 128) { 310 return CHAR_STRING_ARRAY[ch]; 311 } 312 return new String(new char[] {ch}); 313 } 314 315 /** 316 * <p>Converts the character to a String that contains the one character.</p> 317 * 318 * <p>For ASCII 7 bit characters, this uses a cache that will return the 319 * same String object each time.</p> 320 * 321 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 322 * 323 * <pre> 324 * CharUtils.toString(null) = null 325 * CharUtils.toString(' ') = " " 326 * CharUtils.toString('A') = "A" 327 * </pre> 328 * 329 * @param ch the character to convert 330 * @return a String containing the one specified character 331 */ 332 public static String toString(final Character ch) { 333 if (ch == null) { 334 return null; 335 } 336 return toString(ch.charValue()); 337 } 338 339 //-------------------------------------------------------------------------- 340 /** 341 * <p>Converts the string to the Unicode format '\u0020'.</p> 342 * 343 * <p>This format is the Java source code format.</p> 344 * 345 * <pre> 346 * CharUtils.unicodeEscaped(' ') = "\u0020" 347 * CharUtils.unicodeEscaped('A') = "\u0041" 348 * </pre> 349 * 350 * @param ch the character to convert 351 * @return the escaped Unicode string 352 */ 353 public static String unicodeEscaped(final char ch) { 354 return "\\u" + 355 HEX_DIGITS[(ch >> 12) & 15] + 356 HEX_DIGITS[(ch >> 8) & 15] + 357 HEX_DIGITS[(ch >> 4) & 15] + 358 HEX_DIGITS[(ch) & 15]; 359 } 360 361 /** 362 * <p>Converts the string to the Unicode format '\u0020'.</p> 363 * 364 * <p>This format is the Java source code format.</p> 365 * 366 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 367 * 368 * <pre> 369 * CharUtils.unicodeEscaped(null) = null 370 * CharUtils.unicodeEscaped(' ') = "\u0020" 371 * CharUtils.unicodeEscaped('A') = "\u0041" 372 * </pre> 373 * 374 * @param ch the character to convert, may be null 375 * @return the escaped Unicode string, null if null input 376 */ 377 public static String unicodeEscaped(final Character ch) { 378 if (ch == null) { 379 return null; 380 } 381 return unicodeEscaped(ch.charValue()); 382 } 383 384 //-------------------------------------------------------------------------- 385 /** 386 * <p>Checks whether the character is ASCII 7 bit.</p> 387 * 388 * <pre> 389 * CharUtils.isAscii('a') = true 390 * CharUtils.isAscii('A') = true 391 * CharUtils.isAscii('3') = true 392 * CharUtils.isAscii('-') = true 393 * CharUtils.isAscii('\n') = true 394 * CharUtils.isAscii('©') = false 395 * </pre> 396 * 397 * @param ch the character to check 398 * @return true if less than 128 399 */ 400 public static boolean isAscii(final char ch) { 401 return ch < 128; 402 } 403 404 /** 405 * <p>Checks whether the character is ASCII 7 bit printable.</p> 406 * 407 * <pre> 408 * CharUtils.isAsciiPrintable('a') = true 409 * CharUtils.isAsciiPrintable('A') = true 410 * CharUtils.isAsciiPrintable('3') = true 411 * CharUtils.isAsciiPrintable('-') = true 412 * CharUtils.isAsciiPrintable('\n') = false 413 * CharUtils.isAsciiPrintable('©') = false 414 * </pre> 415 * 416 * @param ch the character to check 417 * @return true if between 32 and 126 inclusive 418 */ 419 public static boolean isAsciiPrintable(final char ch) { 420 return ch >= 32 && ch < 127; 421 } 422 423 /** 424 * <p>Checks whether the character is ASCII 7 bit control.</p> 425 * 426 * <pre> 427 * CharUtils.isAsciiControl('a') = false 428 * CharUtils.isAsciiControl('A') = false 429 * CharUtils.isAsciiControl('3') = false 430 * CharUtils.isAsciiControl('-') = false 431 * CharUtils.isAsciiControl('\n') = true 432 * CharUtils.isAsciiControl('©') = false 433 * </pre> 434 * 435 * @param ch the character to check 436 * @return true if less than 32 or equals 127 437 */ 438 public static boolean isAsciiControl(final char ch) { 439 return ch < 32 || ch == 127; 440 } 441 442 /** 443 * <p>Checks whether the character is ASCII 7 bit alphabetic.</p> 444 * 445 * <pre> 446 * CharUtils.isAsciiAlpha('a') = true 447 * CharUtils.isAsciiAlpha('A') = true 448 * CharUtils.isAsciiAlpha('3') = false 449 * CharUtils.isAsciiAlpha('-') = false 450 * CharUtils.isAsciiAlpha('\n') = false 451 * CharUtils.isAsciiAlpha('©') = false 452 * </pre> 453 * 454 * @param ch the character to check 455 * @return true if between 65 and 90 or 97 and 122 inclusive 456 */ 457 public static boolean isAsciiAlpha(final char ch) { 458 return isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch); 459 } 460 461 /** 462 * <p>Checks whether the character is ASCII 7 bit alphabetic upper case.</p> 463 * 464 * <pre> 465 * CharUtils.isAsciiAlphaUpper('a') = false 466 * CharUtils.isAsciiAlphaUpper('A') = true 467 * CharUtils.isAsciiAlphaUpper('3') = false 468 * CharUtils.isAsciiAlphaUpper('-') = false 469 * CharUtils.isAsciiAlphaUpper('\n') = false 470 * CharUtils.isAsciiAlphaUpper('©') = false 471 * </pre> 472 * 473 * @param ch the character to check 474 * @return true if between 65 and 90 inclusive 475 */ 476 public static boolean isAsciiAlphaUpper(final char ch) { 477 return ch >= 'A' && ch <= 'Z'; 478 } 479 480 /** 481 * <p>Checks whether the character is ASCII 7 bit alphabetic lower case.</p> 482 * 483 * <pre> 484 * CharUtils.isAsciiAlphaLower('a') = true 485 * CharUtils.isAsciiAlphaLower('A') = false 486 * CharUtils.isAsciiAlphaLower('3') = false 487 * CharUtils.isAsciiAlphaLower('-') = false 488 * CharUtils.isAsciiAlphaLower('\n') = false 489 * CharUtils.isAsciiAlphaLower('©') = false 490 * </pre> 491 * 492 * @param ch the character to check 493 * @return true if between 97 and 122 inclusive 494 */ 495 public static boolean isAsciiAlphaLower(final char ch) { 496 return ch >= 'a' && ch <= 'z'; 497 } 498 499 /** 500 * <p>Checks whether the character is ASCII 7 bit numeric.</p> 501 * 502 * <pre> 503 * CharUtils.isAsciiNumeric('a') = false 504 * CharUtils.isAsciiNumeric('A') = false 505 * CharUtils.isAsciiNumeric('3') = true 506 * CharUtils.isAsciiNumeric('-') = false 507 * CharUtils.isAsciiNumeric('\n') = false 508 * CharUtils.isAsciiNumeric('©') = false 509 * </pre> 510 * 511 * @param ch the character to check 512 * @return true if between 48 and 57 inclusive 513 */ 514 public static boolean isAsciiNumeric(final char ch) { 515 return ch >= '0' && ch <= '9'; 516 } 517 518 /** 519 * <p>Checks whether the character is ASCII 7 bit numeric.</p> 520 * 521 * <pre> 522 * CharUtils.isAsciiAlphanumeric('a') = true 523 * CharUtils.isAsciiAlphanumeric('A') = true 524 * CharUtils.isAsciiAlphanumeric('3') = true 525 * CharUtils.isAsciiAlphanumeric('-') = false 526 * CharUtils.isAsciiAlphanumeric('\n') = false 527 * CharUtils.isAsciiAlphanumeric('©') = false 528 * </pre> 529 * 530 * @param ch the character to check 531 * @return true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive 532 */ 533 public static boolean isAsciiAlphanumeric(final char ch) { 534 return isAsciiAlpha(ch) || isAsciiNumeric(ch); 535 } 536 537 /** 538 * <p>Compares two {@code char} values numerically. This is the same functionality as provided in Java 7.</p> 539 * 540 * @param x the first {@code char} to compare 541 * @param y the second {@code char} to compare 542 * @return the value {@code 0} if {@code x == y}; 543 * a value less than {@code 0} if {@code x < y}; and 544 * a value greater than {@code 0} if {@code x > y} 545 * @since 3.4 546 */ 547 public static int compare(final char x, final char y) { 548 return x-y; 549 } 550}