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 = new char[] {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'}; 034 035 /** 036 * {@code \u000a} linefeed LF ('\n'). 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 * {@code \u000d} carriage return CR ('\r'). 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 static { 055 for (char c = 0; c < CHAR_STRING_ARRAY.length; c++) { 056 CHAR_STRING_ARRAY[c] = String.valueOf(c); 057 } 058 } 059 060 /** 061 * <p>{@code CharUtils} instances should NOT be constructed in standard programming. 062 * Instead, the class should be used as {@code CharUtils.toString('c');}.</p> 063 * 064 * <p>This constructor is public to permit tools that require a JavaBean instance 065 * to operate.</p> 066 */ 067 public CharUtils() { 068 super(); 069 } 070 071 //----------------------------------------------------------------------- 072 /** 073 * <p>Converts the character to a Character.</p> 074 * 075 * <p>For ASCII 7 bit characters, this uses a cache that will return the 076 * same Character object each time.</p> 077 * 078 * <pre> 079 * CharUtils.toCharacterObject(' ') = ' ' 080 * CharUtils.toCharacterObject('A') = 'A' 081 * </pre> 082 * 083 * @deprecated Java 5 introduced {@link Character#valueOf(char)} which caches chars 0 through 127. 084 * @param ch the character to convert 085 * @return a Character of the specified character 086 */ 087 @Deprecated 088 public static Character toCharacterObject(final char ch) { 089 return Character.valueOf(ch); 090 } 091 092 /** 093 * <p>Converts the String to a Character using the first character, returning 094 * null for empty Strings.</p> 095 * 096 * <p>For ASCII 7 bit characters, this uses a cache that will return the 097 * same Character object each time.</p> 098 * 099 * <pre> 100 * CharUtils.toCharacterObject(null) = null 101 * CharUtils.toCharacterObject("") = null 102 * CharUtils.toCharacterObject("A") = 'A' 103 * CharUtils.toCharacterObject("BA") = 'B' 104 * </pre> 105 * 106 * @param str the character to convert 107 * @return the Character value of the first letter of the String 108 */ 109 public static Character toCharacterObject(final String str) { 110 if (StringUtils.isEmpty(str)) { 111 return null; 112 } 113 return Character.valueOf(str.charAt(0)); 114 } 115 116 //----------------------------------------------------------------------- 117 /** 118 * <p>Converts the Character to a char throwing an exception for {@code null}.</p> 119 * 120 * <pre> 121 * CharUtils.toChar(' ') = ' ' 122 * CharUtils.toChar('A') = 'A' 123 * CharUtils.toChar(null) throws IllegalArgumentException 124 * </pre> 125 * 126 * @param ch the character to convert 127 * @return the char value of the Character 128 * @throws IllegalArgumentException if the Character is null 129 */ 130 public static char toChar(final Character ch) { 131 if (ch == null) { 132 throw new IllegalArgumentException("The Character must not be null"); 133 } 134 return ch.charValue(); 135 } 136 137 /** 138 * <p>Converts the Character to a char handling {@code null}.</p> 139 * 140 * <pre> 141 * CharUtils.toChar(null, 'X') = 'X' 142 * CharUtils.toChar(' ', 'X') = ' ' 143 * CharUtils.toChar('A', 'X') = 'A' 144 * </pre> 145 * 146 * @param ch the character to convert 147 * @param defaultValue the value to use if the Character is null 148 * @return the char value of the Character or the default if null 149 */ 150 public static char toChar(final Character ch, final char defaultValue) { 151 if (ch == null) { 152 return defaultValue; 153 } 154 return ch.charValue(); 155 } 156 157 //----------------------------------------------------------------------- 158 /** 159 * <p>Converts the String to a char using the first character, throwing 160 * an exception on empty Strings.</p> 161 * 162 * <pre> 163 * CharUtils.toChar("A") = 'A' 164 * CharUtils.toChar("BA") = 'B' 165 * CharUtils.toChar(null) throws IllegalArgumentException 166 * CharUtils.toChar("") throws IllegalArgumentException 167 * </pre> 168 * 169 * @param str the character to convert 170 * @return the char value of the first letter of the String 171 * @throws IllegalArgumentException if the String is empty 172 */ 173 public static char toChar(final String str) { 174 if (StringUtils.isEmpty(str)) { 175 throw new IllegalArgumentException("The String must not be empty"); 176 } 177 return str.charAt(0); 178 } 179 180 /** 181 * <p>Converts the String to a char using the first character, defaulting 182 * the value on empty Strings.</p> 183 * 184 * <pre> 185 * CharUtils.toChar(null, 'X') = 'X' 186 * CharUtils.toChar("", 'X') = 'X' 187 * CharUtils.toChar("A", 'X') = 'A' 188 * CharUtils.toChar("BA", 'X') = 'B' 189 * </pre> 190 * 191 * @param str the character to convert 192 * @param defaultValue the value to use if the Character is null 193 * @return the char value of the first letter of the String or the default if null 194 */ 195 public static char toChar(final String str, final char defaultValue) { 196 if (StringUtils.isEmpty(str)) { 197 return defaultValue; 198 } 199 return str.charAt(0); 200 } 201 202 //----------------------------------------------------------------------- 203 /** 204 * <p>Converts the character to the Integer it represents, throwing an 205 * exception if the character is not numeric.</p> 206 * 207 * <p>This method coverts the char '1' to the int 1 and so on.</p> 208 * 209 * <pre> 210 * CharUtils.toIntValue('3') = 3 211 * CharUtils.toIntValue('A') throws IllegalArgumentException 212 * </pre> 213 * 214 * @param ch the character to convert 215 * @return the int value of the character 216 * @throws IllegalArgumentException if the character is not ASCII numeric 217 */ 218 public static int toIntValue(final char ch) { 219 if (isAsciiNumeric(ch) == false) { 220 throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'"); 221 } 222 return ch - 48; 223 } 224 225 /** 226 * <p>Converts the character to the Integer it represents, throwing an 227 * exception if the character is not numeric.</p> 228 * 229 * <p>This method coverts the char '1' to the int 1 and so on.</p> 230 * 231 * <pre> 232 * CharUtils.toIntValue('3', -1) = 3 233 * CharUtils.toIntValue('A', -1) = -1 234 * </pre> 235 * 236 * @param ch the character to convert 237 * @param defaultValue the default value to use if the character is not numeric 238 * @return the int value of the character 239 */ 240 public static int toIntValue(final char ch, final int defaultValue) { 241 if (isAsciiNumeric(ch) == false) { 242 return defaultValue; 243 } 244 return ch - 48; 245 } 246 247 /** 248 * <p>Converts the character to the Integer it represents, throwing an 249 * exception if the character is not numeric.</p> 250 * 251 * <p>This method coverts the char '1' to the int 1 and so on.</p> 252 * 253 * <pre> 254 * CharUtils.toIntValue('3') = 3 255 * CharUtils.toIntValue(null) throws IllegalArgumentException 256 * CharUtils.toIntValue('A') throws IllegalArgumentException 257 * </pre> 258 * 259 * @param ch the character to convert, not null 260 * @return the int value of the character 261 * @throws IllegalArgumentException if the Character is not ASCII numeric or is null 262 */ 263 public static int toIntValue(final Character ch) { 264 if (ch == null) { 265 throw new IllegalArgumentException("The character must not be null"); 266 } 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 coverts 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 StringBuilder sb = new StringBuilder(6); 355 sb.append("\\u"); 356 sb.append(HEX_DIGITS[(ch >> 12) & 15]); 357 sb.append(HEX_DIGITS[(ch >> 8) & 15]); 358 sb.append(HEX_DIGITS[(ch >> 4) & 15]); 359 sb.append(HEX_DIGITS[(ch) & 15]); 360 return sb.toString(); 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(char x, char y) { 550 return x-y; 551 } 552}