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 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 NullPointerException 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 NullPointerException if the string is null 176 * @throws IllegalArgumentException if the String is empty 177 */ 178 public static char toChar(final String str) { 179 Validate.notEmpty(str, "The String must not be empty"); 180 return str.charAt(0); 181 } 182 183 /** 184 * <p>Converts the String to a char using the first character, defaulting 185 * the value on empty Strings.</p> 186 * 187 * <pre> 188 * CharUtils.toChar(null, 'X') = 'X' 189 * CharUtils.toChar("", 'X') = 'X' 190 * CharUtils.toChar("A", 'X') = 'A' 191 * CharUtils.toChar("BA", 'X') = 'B' 192 * </pre> 193 * 194 * @param str the character to convert 195 * @param defaultValue the value to use if the Character is null 196 * @return the char value of the first letter of the String or the default if null 197 */ 198 public static char toChar(final String str, final char defaultValue) { 199 if (StringUtils.isEmpty(str)) { 200 return defaultValue; 201 } 202 return str.charAt(0); 203 } 204 205 //----------------------------------------------------------------------- 206 /** 207 * <p>Converts the character to the Integer it represents, throwing an 208 * exception if the character is not numeric.</p> 209 * 210 * <p>This method converts the char '1' to the int 1 and so on.</p> 211 * 212 * <pre> 213 * CharUtils.toIntValue('3') = 3 214 * CharUtils.toIntValue('A') throws IllegalArgumentException 215 * </pre> 216 * 217 * @param ch the character to convert 218 * @return the int value of the character 219 * @throws IllegalArgumentException if the character is not ASCII numeric 220 */ 221 public static int toIntValue(final char ch) { 222 if (!isAsciiNumeric(ch)) { 223 throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'"); 224 } 225 return ch - 48; 226 } 227 228 /** 229 * <p>Converts the character to the Integer it represents, throwing an 230 * exception if the character is not numeric.</p> 231 * 232 * <p>This method converts the char '1' to the int 1 and so on.</p> 233 * 234 * <pre> 235 * CharUtils.toIntValue('3', -1) = 3 236 * CharUtils.toIntValue('A', -1) = -1 237 * </pre> 238 * 239 * @param ch the character to convert 240 * @param defaultValue the default value to use if the character is not numeric 241 * @return the int value of the character 242 */ 243 public static int toIntValue(final char ch, final int defaultValue) { 244 if (!isAsciiNumeric(ch)) { 245 return defaultValue; 246 } 247 return ch - 48; 248 } 249 250 /** 251 * <p>Converts the character to the Integer it represents, throwing an 252 * exception if the character is not numeric.</p> 253 * 254 * <p>This method converts the char '1' to the int 1 and so on.</p> 255 * 256 * <pre> 257 * CharUtils.toIntValue('3') = 3 258 * CharUtils.toIntValue(null) throws IllegalArgumentException 259 * CharUtils.toIntValue('A') throws IllegalArgumentException 260 * </pre> 261 * 262 * @param ch the character to convert, not null 263 * @return the int value of the character 264 * @throws NullPointerException if the Character is null 265 * @throws IllegalArgumentException if the Character is not ASCII numeric 266 */ 267 public static int toIntValue(final Character ch) { 268 Validate.notNull(ch, "The character must not be null"); 269 return toIntValue(ch.charValue()); 270 } 271 272 /** 273 * <p>Converts the character to the Integer it represents, throwing an 274 * exception if the character is not numeric.</p> 275 * 276 * <p>This method converts the char '1' to the int 1 and so on.</p> 277 * 278 * <pre> 279 * CharUtils.toIntValue(null, -1) = -1 280 * CharUtils.toIntValue('3', -1) = 3 281 * CharUtils.toIntValue('A', -1) = -1 282 * </pre> 283 * 284 * @param ch the character to convert 285 * @param defaultValue the default value to use if the character is not numeric 286 * @return the int value of the character 287 */ 288 public static int toIntValue(final Character ch, final int defaultValue) { 289 if (ch == null) { 290 return defaultValue; 291 } 292 return toIntValue(ch.charValue(), defaultValue); 293 } 294 295 //----------------------------------------------------------------------- 296 /** 297 * <p>Converts the character to a String that contains the one character.</p> 298 * 299 * <p>For ASCII 7 bit characters, this uses a cache that will return the 300 * same String object each time.</p> 301 * 302 * <pre> 303 * CharUtils.toString(' ') = " " 304 * CharUtils.toString('A') = "A" 305 * </pre> 306 * 307 * @param ch the character to convert 308 * @return a String containing the one specified character 309 */ 310 public static String toString(final char ch) { 311 if (ch < 128) { 312 return CHAR_STRING_ARRAY[ch]; 313 } 314 return new String(new char[] {ch}); 315 } 316 317 /** 318 * <p>Converts the character to a String that contains the one character.</p> 319 * 320 * <p>For ASCII 7 bit characters, this uses a cache that will return the 321 * same String object each time.</p> 322 * 323 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 324 * 325 * <pre> 326 * CharUtils.toString(null) = null 327 * CharUtils.toString(' ') = " " 328 * CharUtils.toString('A') = "A" 329 * </pre> 330 * 331 * @param ch the character to convert 332 * @return a String containing the one specified character 333 */ 334 public static String toString(final Character ch) { 335 if (ch == null) { 336 return null; 337 } 338 return toString(ch.charValue()); 339 } 340 341 //-------------------------------------------------------------------------- 342 /** 343 * <p>Converts the string to the Unicode format '\u0020'.</p> 344 * 345 * <p>This format is the Java source code format.</p> 346 * 347 * <pre> 348 * CharUtils.unicodeEscaped(' ') = "\u0020" 349 * CharUtils.unicodeEscaped('A') = "\u0041" 350 * </pre> 351 * 352 * @param ch the character to convert 353 * @return the escaped Unicode string 354 */ 355 public static String unicodeEscaped(final char ch) { 356 return "\\u" + 357 HEX_DIGITS[(ch >> 12) & 15] + 358 HEX_DIGITS[(ch >> 8) & 15] + 359 HEX_DIGITS[(ch >> 4) & 15] + 360 HEX_DIGITS[(ch) & 15]; 361 } 362 363 /** 364 * <p>Converts the string to the Unicode format '\u0020'.</p> 365 * 366 * <p>This format is the Java source code format.</p> 367 * 368 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 369 * 370 * <pre> 371 * CharUtils.unicodeEscaped(null) = null 372 * CharUtils.unicodeEscaped(' ') = "\u0020" 373 * CharUtils.unicodeEscaped('A') = "\u0041" 374 * </pre> 375 * 376 * @param ch the character to convert, may be null 377 * @return the escaped Unicode string, null if null input 378 */ 379 public static String unicodeEscaped(final Character ch) { 380 if (ch == null) { 381 return null; 382 } 383 return unicodeEscaped(ch.charValue()); 384 } 385 386 //-------------------------------------------------------------------------- 387 /** 388 * <p>Checks whether the character is ASCII 7 bit.</p> 389 * 390 * <pre> 391 * CharUtils.isAscii('a') = true 392 * CharUtils.isAscii('A') = true 393 * CharUtils.isAscii('3') = true 394 * CharUtils.isAscii('-') = true 395 * CharUtils.isAscii('\n') = true 396 * CharUtils.isAscii('©') = false 397 * </pre> 398 * 399 * @param ch the character to check 400 * @return true if less than 128 401 */ 402 public static boolean isAscii(final char ch) { 403 return ch < 128; 404 } 405 406 /** 407 * <p>Checks whether the character is ASCII 7 bit printable.</p> 408 * 409 * <pre> 410 * CharUtils.isAsciiPrintable('a') = true 411 * CharUtils.isAsciiPrintable('A') = true 412 * CharUtils.isAsciiPrintable('3') = true 413 * CharUtils.isAsciiPrintable('-') = true 414 * CharUtils.isAsciiPrintable('\n') = false 415 * CharUtils.isAsciiPrintable('©') = false 416 * </pre> 417 * 418 * @param ch the character to check 419 * @return true if between 32 and 126 inclusive 420 */ 421 public static boolean isAsciiPrintable(final char ch) { 422 return ch >= 32 && ch < 127; 423 } 424 425 /** 426 * <p>Checks whether the character is ASCII 7 bit control.</p> 427 * 428 * <pre> 429 * CharUtils.isAsciiControl('a') = false 430 * CharUtils.isAsciiControl('A') = false 431 * CharUtils.isAsciiControl('3') = false 432 * CharUtils.isAsciiControl('-') = false 433 * CharUtils.isAsciiControl('\n') = true 434 * CharUtils.isAsciiControl('©') = false 435 * </pre> 436 * 437 * @param ch the character to check 438 * @return true if less than 32 or equals 127 439 */ 440 public static boolean isAsciiControl(final char ch) { 441 return ch < 32 || ch == 127; 442 } 443 444 /** 445 * <p>Checks whether the character is ASCII 7 bit alphabetic.</p> 446 * 447 * <pre> 448 * CharUtils.isAsciiAlpha('a') = true 449 * CharUtils.isAsciiAlpha('A') = true 450 * CharUtils.isAsciiAlpha('3') = false 451 * CharUtils.isAsciiAlpha('-') = false 452 * CharUtils.isAsciiAlpha('\n') = false 453 * CharUtils.isAsciiAlpha('©') = false 454 * </pre> 455 * 456 * @param ch the character to check 457 * @return true if between 65 and 90 or 97 and 122 inclusive 458 */ 459 public static boolean isAsciiAlpha(final char ch) { 460 return isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch); 461 } 462 463 /** 464 * <p>Checks whether the character is ASCII 7 bit alphabetic upper case.</p> 465 * 466 * <pre> 467 * CharUtils.isAsciiAlphaUpper('a') = false 468 * CharUtils.isAsciiAlphaUpper('A') = true 469 * CharUtils.isAsciiAlphaUpper('3') = false 470 * CharUtils.isAsciiAlphaUpper('-') = false 471 * CharUtils.isAsciiAlphaUpper('\n') = false 472 * CharUtils.isAsciiAlphaUpper('©') = false 473 * </pre> 474 * 475 * @param ch the character to check 476 * @return true if between 65 and 90 inclusive 477 */ 478 public static boolean isAsciiAlphaUpper(final char ch) { 479 return ch >= 'A' && ch <= 'Z'; 480 } 481 482 /** 483 * <p>Checks whether the character is ASCII 7 bit alphabetic lower case.</p> 484 * 485 * <pre> 486 * CharUtils.isAsciiAlphaLower('a') = true 487 * CharUtils.isAsciiAlphaLower('A') = false 488 * CharUtils.isAsciiAlphaLower('3') = false 489 * CharUtils.isAsciiAlphaLower('-') = false 490 * CharUtils.isAsciiAlphaLower('\n') = false 491 * CharUtils.isAsciiAlphaLower('©') = false 492 * </pre> 493 * 494 * @param ch the character to check 495 * @return true if between 97 and 122 inclusive 496 */ 497 public static boolean isAsciiAlphaLower(final char ch) { 498 return ch >= 'a' && ch <= 'z'; 499 } 500 501 /** 502 * <p>Checks whether the character is ASCII 7 bit numeric.</p> 503 * 504 * <pre> 505 * CharUtils.isAsciiNumeric('a') = false 506 * CharUtils.isAsciiNumeric('A') = false 507 * CharUtils.isAsciiNumeric('3') = true 508 * CharUtils.isAsciiNumeric('-') = false 509 * CharUtils.isAsciiNumeric('\n') = false 510 * CharUtils.isAsciiNumeric('©') = false 511 * </pre> 512 * 513 * @param ch the character to check 514 * @return true if between 48 and 57 inclusive 515 */ 516 public static boolean isAsciiNumeric(final char ch) { 517 return ch >= '0' && ch <= '9'; 518 } 519 520 /** 521 * <p>Checks whether the character is ASCII 7 bit numeric.</p> 522 * 523 * <pre> 524 * CharUtils.isAsciiAlphanumeric('a') = true 525 * CharUtils.isAsciiAlphanumeric('A') = true 526 * CharUtils.isAsciiAlphanumeric('3') = true 527 * CharUtils.isAsciiAlphanumeric('-') = false 528 * CharUtils.isAsciiAlphanumeric('\n') = false 529 * CharUtils.isAsciiAlphanumeric('©') = false 530 * </pre> 531 * 532 * @param ch the character to check 533 * @return true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive 534 */ 535 public static boolean isAsciiAlphanumeric(final char ch) { 536 return isAsciiAlpha(ch) || isAsciiNumeric(ch); 537 } 538 539 /** 540 * <p>Compares two {@code char} values numerically. This is the same functionality as provided in Java 7.</p> 541 * 542 * @param x the first {@code char} to compare 543 * @param y the second {@code char} to compare 544 * @return the value {@code 0} if {@code x == y}; 545 * a value less than {@code 0} if {@code x < y}; and 546 * a value greater than {@code 0} if {@code x > y} 547 * @since 3.4 548 */ 549 public static int compare(final char x, final char y) { 550 return x-y; 551 } 552}