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 * @version $Id: CharUtils.java 1666535 2015-03-13 18:18:59Z britter $ 029 */ 030public class CharUtils { 031 032 private static final String[] CHAR_STRING_ARRAY = new String[128]; 033 034 private static final char[] HEX_DIGITS = new char[] {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'}; 035 036 /** 037 * {@code \u000a} linefeed LF ('\n'). 038 * 039 * @see <a href="http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences 040 * for Character and String Literals</a> 041 * @since 2.2 042 */ 043 public static final char LF = '\n'; 044 045 /** 046 * {@code \u000d} carriage return CR ('\r'). 047 * 048 * @see <a href="http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences 049 * for Character and String Literals</a> 050 * @since 2.2 051 */ 052 public static final char CR = '\r'; 053 054 055 static { 056 for (char c = 0; c < CHAR_STRING_ARRAY.length; c++) { 057 CHAR_STRING_ARRAY[c] = String.valueOf(c); 058 } 059 } 060 061 /** 062 * <p>{@code CharUtils} instances should NOT be constructed in standard programming. 063 * Instead, the class should be used as {@code CharUtils.toString('c');}.</p> 064 * 065 * <p>This constructor is public to permit tools that require a JavaBean instance 066 * to operate.</p> 067 */ 068 public CharUtils() { 069 super(); 070 } 071 072 //----------------------------------------------------------------------- 073 /** 074 * <p>Converts the character to a Character.</p> 075 * 076 * <p>For ASCII 7 bit characters, this uses a cache that will return the 077 * same Character object each time.</p> 078 * 079 * <pre> 080 * CharUtils.toCharacterObject(' ') = ' ' 081 * CharUtils.toCharacterObject('A') = 'A' 082 * </pre> 083 * 084 * @deprecated Java 5 introduced {@link Character#valueOf(char)} which caches chars 0 through 127. 085 * @param ch the character to convert 086 * @return a Character of the specified character 087 */ 088 @Deprecated 089 public static Character toCharacterObject(final char ch) { 090 return Character.valueOf(ch); 091 } 092 093 /** 094 * <p>Converts the String to a Character using the first character, returning 095 * null for empty Strings.</p> 096 * 097 * <p>For ASCII 7 bit characters, this uses a cache that will return the 098 * same Character object each time.</p> 099 * 100 * <pre> 101 * CharUtils.toCharacterObject(null) = null 102 * CharUtils.toCharacterObject("") = null 103 * CharUtils.toCharacterObject("A") = 'A' 104 * CharUtils.toCharacterObject("BA") = 'B' 105 * </pre> 106 * 107 * @param str the character to convert 108 * @return the Character value of the first letter of the String 109 */ 110 public static Character toCharacterObject(final String str) { 111 if (StringUtils.isEmpty(str)) { 112 return null; 113 } 114 return Character.valueOf(str.charAt(0)); 115 } 116 117 //----------------------------------------------------------------------- 118 /** 119 * <p>Converts the Character to a char throwing an exception for {@code null}.</p> 120 * 121 * <pre> 122 * CharUtils.toChar(' ') = ' ' 123 * CharUtils.toChar('A') = 'A' 124 * CharUtils.toChar(null) throws IllegalArgumentException 125 * </pre> 126 * 127 * @param ch the character to convert 128 * @return the char value of the Character 129 * @throws IllegalArgumentException if the Character is null 130 */ 131 public static char toChar(final Character ch) { 132 if (ch == null) { 133 throw new IllegalArgumentException("The Character must not be null"); 134 } 135 return ch.charValue(); 136 } 137 138 /** 139 * <p>Converts the Character to a char handling {@code null}.</p> 140 * 141 * <pre> 142 * CharUtils.toChar(null, 'X') = 'X' 143 * CharUtils.toChar(' ', 'X') = ' ' 144 * CharUtils.toChar('A', 'X') = 'A' 145 * </pre> 146 * 147 * @param ch the character to convert 148 * @param defaultValue the value to use if the Character is null 149 * @return the char value of the Character or the default if null 150 */ 151 public static char toChar(final Character ch, final char defaultValue) { 152 if (ch == null) { 153 return defaultValue; 154 } 155 return ch.charValue(); 156 } 157 158 //----------------------------------------------------------------------- 159 /** 160 * <p>Converts the String to a char using the first character, throwing 161 * an exception on empty Strings.</p> 162 * 163 * <pre> 164 * CharUtils.toChar("A") = 'A' 165 * CharUtils.toChar("BA") = 'B' 166 * CharUtils.toChar(null) throws IllegalArgumentException 167 * CharUtils.toChar("") throws IllegalArgumentException 168 * </pre> 169 * 170 * @param str the character to convert 171 * @return the char value of the first letter of the String 172 * @throws IllegalArgumentException if the String is empty 173 */ 174 public static char toChar(final String str) { 175 if (StringUtils.isEmpty(str)) { 176 throw new IllegalArgumentException("The String must not be empty"); 177 } 178 return str.charAt(0); 179 } 180 181 /** 182 * <p>Converts the String to a char using the first character, defaulting 183 * the value on empty Strings.</p> 184 * 185 * <pre> 186 * CharUtils.toChar(null, 'X') = 'X' 187 * CharUtils.toChar("", 'X') = 'X' 188 * CharUtils.toChar("A", 'X') = 'A' 189 * CharUtils.toChar("BA", 'X') = 'B' 190 * </pre> 191 * 192 * @param str the character to convert 193 * @param defaultValue the value to use if the Character is null 194 * @return the char value of the first letter of the String or the default if null 195 */ 196 public static char toChar(final String str, final char defaultValue) { 197 if (StringUtils.isEmpty(str)) { 198 return defaultValue; 199 } 200 return str.charAt(0); 201 } 202 203 //----------------------------------------------------------------------- 204 /** 205 * <p>Converts the character to the Integer it represents, throwing an 206 * exception if the character is not numeric.</p> 207 * 208 * <p>This method coverts the char '1' to the int 1 and so on.</p> 209 * 210 * <pre> 211 * CharUtils.toIntValue('3') = 3 212 * CharUtils.toIntValue('A') throws IllegalArgumentException 213 * </pre> 214 * 215 * @param ch the character to convert 216 * @return the int value of the character 217 * @throws IllegalArgumentException if the character is not ASCII numeric 218 */ 219 public static int toIntValue(final char ch) { 220 if (isAsciiNumeric(ch) == false) { 221 throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'"); 222 } 223 return ch - 48; 224 } 225 226 /** 227 * <p>Converts the character to the Integer it represents, throwing an 228 * exception if the character is not numeric.</p> 229 * 230 * <p>This method coverts the char '1' to the int 1 and so on.</p> 231 * 232 * <pre> 233 * CharUtils.toIntValue('3', -1) = 3 234 * CharUtils.toIntValue('A', -1) = -1 235 * </pre> 236 * 237 * @param ch the character to convert 238 * @param defaultValue the default value to use if the character is not numeric 239 * @return the int value of the character 240 */ 241 public static int toIntValue(final char ch, final int defaultValue) { 242 if (isAsciiNumeric(ch) == false) { 243 return defaultValue; 244 } 245 return ch - 48; 246 } 247 248 /** 249 * <p>Converts the character to the Integer it represents, throwing an 250 * exception if the character is not numeric.</p> 251 * 252 * <p>This method coverts the char '1' to the int 1 and so on.</p> 253 * 254 * <pre> 255 * CharUtils.toIntValue('3') = 3 256 * CharUtils.toIntValue(null) throws IllegalArgumentException 257 * CharUtils.toIntValue('A') throws IllegalArgumentException 258 * </pre> 259 * 260 * @param ch the character to convert, not null 261 * @return the int value of the character 262 * @throws IllegalArgumentException if the Character is not ASCII numeric or is null 263 */ 264 public static int toIntValue(final Character ch) { 265 if (ch == null) { 266 throw new IllegalArgumentException("The character must not be null"); 267 } 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 coverts 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 StringBuilder sb = new StringBuilder(6); 356 sb.append("\\u"); 357 sb.append(HEX_DIGITS[(ch >> 12) & 15]); 358 sb.append(HEX_DIGITS[(ch >> 8) & 15]); 359 sb.append(HEX_DIGITS[(ch >> 4) & 15]); 360 sb.append(HEX_DIGITS[(ch) & 15]); 361 return sb.toString(); 362 } 363 364 /** 365 * <p>Converts the string to the Unicode format '\u0020'.</p> 366 * 367 * <p>This format is the Java source code format.</p> 368 * 369 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 370 * 371 * <pre> 372 * CharUtils.unicodeEscaped(null) = null 373 * CharUtils.unicodeEscaped(' ') = "\u0020" 374 * CharUtils.unicodeEscaped('A') = "\u0041" 375 * </pre> 376 * 377 * @param ch the character to convert, may be null 378 * @return the escaped Unicode string, null if null input 379 */ 380 public static String unicodeEscaped(final Character ch) { 381 if (ch == null) { 382 return null; 383 } 384 return unicodeEscaped(ch.charValue()); 385 } 386 387 //-------------------------------------------------------------------------- 388 /** 389 * <p>Checks whether the character is ASCII 7 bit.</p> 390 * 391 * <pre> 392 * CharUtils.isAscii('a') = true 393 * CharUtils.isAscii('A') = true 394 * CharUtils.isAscii('3') = true 395 * CharUtils.isAscii('-') = true 396 * CharUtils.isAscii('\n') = true 397 * CharUtils.isAscii('©') = false 398 * </pre> 399 * 400 * @param ch the character to check 401 * @return true if less than 128 402 */ 403 public static boolean isAscii(final char ch) { 404 return ch < 128; 405 } 406 407 /** 408 * <p>Checks whether the character is ASCII 7 bit printable.</p> 409 * 410 * <pre> 411 * CharUtils.isAsciiPrintable('a') = true 412 * CharUtils.isAsciiPrintable('A') = true 413 * CharUtils.isAsciiPrintable('3') = true 414 * CharUtils.isAsciiPrintable('-') = true 415 * CharUtils.isAsciiPrintable('\n') = false 416 * CharUtils.isAsciiPrintable('©') = false 417 * </pre> 418 * 419 * @param ch the character to check 420 * @return true if between 32 and 126 inclusive 421 */ 422 public static boolean isAsciiPrintable(final char ch) { 423 return ch >= 32 && ch < 127; 424 } 425 426 /** 427 * <p>Checks whether the character is ASCII 7 bit control.</p> 428 * 429 * <pre> 430 * CharUtils.isAsciiControl('a') = false 431 * CharUtils.isAsciiControl('A') = false 432 * CharUtils.isAsciiControl('3') = false 433 * CharUtils.isAsciiControl('-') = false 434 * CharUtils.isAsciiControl('\n') = true 435 * CharUtils.isAsciiControl('©') = false 436 * </pre> 437 * 438 * @param ch the character to check 439 * @return true if less than 32 or equals 127 440 */ 441 public static boolean isAsciiControl(final char ch) { 442 return ch < 32 || ch == 127; 443 } 444 445 /** 446 * <p>Checks whether the character is ASCII 7 bit alphabetic.</p> 447 * 448 * <pre> 449 * CharUtils.isAsciiAlpha('a') = true 450 * CharUtils.isAsciiAlpha('A') = true 451 * CharUtils.isAsciiAlpha('3') = false 452 * CharUtils.isAsciiAlpha('-') = false 453 * CharUtils.isAsciiAlpha('\n') = false 454 * CharUtils.isAsciiAlpha('©') = false 455 * </pre> 456 * 457 * @param ch the character to check 458 * @return true if between 65 and 90 or 97 and 122 inclusive 459 */ 460 public static boolean isAsciiAlpha(final char ch) { 461 return isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch); 462 } 463 464 /** 465 * <p>Checks whether the character is ASCII 7 bit alphabetic upper case.</p> 466 * 467 * <pre> 468 * CharUtils.isAsciiAlphaUpper('a') = false 469 * CharUtils.isAsciiAlphaUpper('A') = true 470 * CharUtils.isAsciiAlphaUpper('3') = false 471 * CharUtils.isAsciiAlphaUpper('-') = false 472 * CharUtils.isAsciiAlphaUpper('\n') = false 473 * CharUtils.isAsciiAlphaUpper('©') = false 474 * </pre> 475 * 476 * @param ch the character to check 477 * @return true if between 65 and 90 inclusive 478 */ 479 public static boolean isAsciiAlphaUpper(final char ch) { 480 return ch >= 'A' && ch <= 'Z'; 481 } 482 483 /** 484 * <p>Checks whether the character is ASCII 7 bit alphabetic lower case.</p> 485 * 486 * <pre> 487 * CharUtils.isAsciiAlphaLower('a') = true 488 * CharUtils.isAsciiAlphaLower('A') = false 489 * CharUtils.isAsciiAlphaLower('3') = false 490 * CharUtils.isAsciiAlphaLower('-') = false 491 * CharUtils.isAsciiAlphaLower('\n') = false 492 * CharUtils.isAsciiAlphaLower('©') = false 493 * </pre> 494 * 495 * @param ch the character to check 496 * @return true if between 97 and 122 inclusive 497 */ 498 public static boolean isAsciiAlphaLower(final char ch) { 499 return ch >= 'a' && ch <= 'z'; 500 } 501 502 /** 503 * <p>Checks whether the character is ASCII 7 bit numeric.</p> 504 * 505 * <pre> 506 * CharUtils.isAsciiNumeric('a') = false 507 * CharUtils.isAsciiNumeric('A') = false 508 * CharUtils.isAsciiNumeric('3') = true 509 * CharUtils.isAsciiNumeric('-') = false 510 * CharUtils.isAsciiNumeric('\n') = false 511 * CharUtils.isAsciiNumeric('©') = false 512 * </pre> 513 * 514 * @param ch the character to check 515 * @return true if between 48 and 57 inclusive 516 */ 517 public static boolean isAsciiNumeric(final char ch) { 518 return ch >= '0' && ch <= '9'; 519 } 520 521 /** 522 * <p>Checks whether the character is ASCII 7 bit numeric.</p> 523 * 524 * <pre> 525 * CharUtils.isAsciiAlphanumeric('a') = true 526 * CharUtils.isAsciiAlphanumeric('A') = true 527 * CharUtils.isAsciiAlphanumeric('3') = true 528 * CharUtils.isAsciiAlphanumeric('-') = false 529 * CharUtils.isAsciiAlphanumeric('\n') = false 530 * CharUtils.isAsciiAlphanumeric('©') = false 531 * </pre> 532 * 533 * @param ch the character to check 534 * @return true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive 535 */ 536 public static boolean isAsciiAlphanumeric(final char ch) { 537 return isAsciiAlpha(ch) || isAsciiNumeric(ch); 538 } 539 540 /** 541 * <p>Compares two {@code char} values numerically. This is the same functionality as provided in Java 7.</p> 542 * 543 * @param x the first {@code char} to compare 544 * @param y the second {@code char} to compare 545 * @return the value {@code 0} if {@code x == y}; 546 * a value less than {@code 0} if {@code x < y}; and 547 * a value greater than {@code 0} if {@code x > y} 548 * @since 3.4 549 */ 550 public static int compare(char x, char y) { 551 return x-y; 552 } 553}