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 * https://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 019import java.util.Objects; 020 021/** 022 * Operations on char primitives and Character objects. 023 * 024 * <p>This class tries to handle {@code null} input gracefully. 025 * An exception will not be thrown for a {@code null} input. 026 * Each method documents its behavior in more detail.</p> 027 * 028 * <p>#ThreadSafe#</p> 029 * @since 2.1 030 */ 031public class CharUtils { 032 033 private static final String[] CHAR_STRING_ARRAY = ArrayUtils.setAll(new String[128], i -> String.valueOf((char) i)); 034 035 private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}; 036 037 /** 038 * Linefeed character LF ({@code '\n'}, Unicode 000a). 039 * 040 * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences 041 * for Character and String Literals</a> 042 * @since 2.2 043 */ 044 public static final char LF = '\n'; 045 046 /** 047 * Carriage return character CR ('\r', Unicode 000d). 048 * 049 * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences 050 * for Character and String Literals</a> 051 * @since 2.2 052 */ 053 public static final char CR = '\r'; 054 055 /** 056 * {@code \u0000} null control character ('\0'), abbreviated NUL. 057 * 058 * @since 3.6 059 */ 060 public static final char NUL = '\0'; 061 062 /** 063 * Compares two {@code char} values numerically. This is the same functionality as provided in Java 7. 064 * 065 * @param x the first {@code char} to compare 066 * @param y the second {@code char} to compare 067 * @return the value {@code 0} if {@code x == y}; 068 * a value less than {@code 0} if {@code x < y}; and 069 * a value greater than {@code 0} if {@code x > y} 070 * @since 3.4 071 */ 072 public static int compare(final char x, final char y) { 073 return x - y; 074 } 075 076 /** 077 * Tests whether the character is ASCII 7 bit. 078 * 079 * <pre> 080 * CharUtils.isAscii('a') = true 081 * CharUtils.isAscii('A') = true 082 * CharUtils.isAscii('3') = true 083 * CharUtils.isAscii('-') = true 084 * CharUtils.isAscii('\n') = true 085 * CharUtils.isAscii('©') = false 086 * </pre> 087 * 088 * @param ch the character to check 089 * @return true if less than 128 090 */ 091 public static boolean isAscii(final char ch) { 092 return ch < 128; 093 } 094 095 /** 096 * Tests whether the character is ASCII 7 bit alphabetic. 097 * 098 * <pre> 099 * CharUtils.isAsciiAlpha('a') = true 100 * CharUtils.isAsciiAlpha('A') = true 101 * CharUtils.isAsciiAlpha('3') = false 102 * CharUtils.isAsciiAlpha('-') = false 103 * CharUtils.isAsciiAlpha('\n') = false 104 * CharUtils.isAsciiAlpha('©') = false 105 * </pre> 106 * 107 * @param ch the character to check 108 * @return true if between 65 and 90 or 97 and 122 inclusive 109 */ 110 public static boolean isAsciiAlpha(final char ch) { 111 return isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch); 112 } 113 114 /** 115 * Tests whether the character is ASCII 7 bit alphabetic lower case. 116 * 117 * <pre> 118 * CharUtils.isAsciiAlphaLower('a') = true 119 * CharUtils.isAsciiAlphaLower('A') = false 120 * CharUtils.isAsciiAlphaLower('3') = false 121 * CharUtils.isAsciiAlphaLower('-') = false 122 * CharUtils.isAsciiAlphaLower('\n') = false 123 * CharUtils.isAsciiAlphaLower('©') = false 124 * </pre> 125 * 126 * @param ch the character to check 127 * @return true if between 97 and 122 inclusive 128 */ 129 public static boolean isAsciiAlphaLower(final char ch) { 130 return ch >= 'a' && ch <= 'z'; 131 } 132 133 /** 134 * Tests whether the character is ASCII 7 bit numeric. 135 * 136 * <pre> 137 * CharUtils.isAsciiAlphanumeric('a') = true 138 * CharUtils.isAsciiAlphanumeric('A') = true 139 * CharUtils.isAsciiAlphanumeric('3') = true 140 * CharUtils.isAsciiAlphanumeric('-') = false 141 * CharUtils.isAsciiAlphanumeric('\n') = false 142 * CharUtils.isAsciiAlphanumeric('©') = false 143 * </pre> 144 * 145 * @param ch the character to check 146 * @return true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive 147 */ 148 public static boolean isAsciiAlphanumeric(final char ch) { 149 return isAsciiAlpha(ch) || isAsciiNumeric(ch); 150 } 151 152 /** 153 * Tests whether the character is ASCII 7 bit alphabetic upper case. 154 * 155 * <pre> 156 * CharUtils.isAsciiAlphaUpper('a') = false 157 * CharUtils.isAsciiAlphaUpper('A') = true 158 * CharUtils.isAsciiAlphaUpper('3') = false 159 * CharUtils.isAsciiAlphaUpper('-') = false 160 * CharUtils.isAsciiAlphaUpper('\n') = false 161 * CharUtils.isAsciiAlphaUpper('©') = false 162 * </pre> 163 * 164 * @param ch the character to check 165 * @return true if between 65 and 90 inclusive 166 */ 167 public static boolean isAsciiAlphaUpper(final char ch) { 168 return ch >= 'A' && ch <= 'Z'; 169 } 170 171 /** 172 * Tests whether the character is ASCII 7 bit control. 173 * 174 * <pre> 175 * CharUtils.isAsciiControl('a') = false 176 * CharUtils.isAsciiControl('A') = false 177 * CharUtils.isAsciiControl('3') = false 178 * CharUtils.isAsciiControl('-') = false 179 * CharUtils.isAsciiControl('\n') = true 180 * CharUtils.isAsciiControl('©') = false 181 * </pre> 182 * 183 * @param ch the character to check 184 * @return true if less than 32 or equals 127 185 */ 186 public static boolean isAsciiControl(final char ch) { 187 return ch < 32 || ch == 127; 188 } 189 190 /** 191 * Tests whether the character is ASCII 7 bit numeric. 192 * 193 * <pre> 194 * CharUtils.isAsciiNumeric('a') = false 195 * CharUtils.isAsciiNumeric('A') = false 196 * CharUtils.isAsciiNumeric('3') = true 197 * CharUtils.isAsciiNumeric('-') = false 198 * CharUtils.isAsciiNumeric('\n') = false 199 * CharUtils.isAsciiNumeric('©') = false 200 * </pre> 201 * 202 * @param ch the character to check 203 * @return true if between 48 and 57 inclusive 204 */ 205 public static boolean isAsciiNumeric(final char ch) { 206 return ch >= '0' && ch <= '9'; 207 } 208 209 /** 210 * Tests whether the character is ASCII 7 bit printable. 211 * 212 * <pre> 213 * CharUtils.isAsciiPrintable('a') = true 214 * CharUtils.isAsciiPrintable('A') = true 215 * CharUtils.isAsciiPrintable('3') = true 216 * CharUtils.isAsciiPrintable('-') = true 217 * CharUtils.isAsciiPrintable('\n') = false 218 * CharUtils.isAsciiPrintable('©') = false 219 * </pre> 220 * 221 * @param ch the character to check 222 * @return true if between 32 and 126 inclusive 223 */ 224 public static boolean isAsciiPrintable(final char ch) { 225 return ch >= 32 && ch < 127; 226 } 227 228 /** 229 * Tests whether a character is a hexadecimal character. 230 * 231 * <pre> 232 * CharUtils.isHex('0') = true 233 * CharUtils.isHex('3') = true 234 * CharUtils.isHex('9') = true 235 * CharUtils.isHex('a') = true 236 * CharUtils.isHex('f') = true 237 * CharUtils.isHex('g') = false 238 * CharUtils.isHex('A') = true 239 * CharUtils.isHex('F') = true 240 * CharUtils.isHex('G') = false 241 * CharUtils.isHex('#') = false 242 * CharUtils.isHex('-') = false 243 * CharUtils.isHex('\n') = false 244 * CharUtils.isHex('©') = false 245 * </pre> 246 * 247 * @param ch the character to test. 248 * @return true if character is a hexadecimal character. 249 * @since 3.18.0 250 */ 251 public static boolean isHex(final char ch) { 252 return isAsciiNumeric(ch) || ch >= 'a' && ch <= 'f' || ch >= 'A' && ch <= 'F'; 253 } 254 255 /** 256 * Tests if the given char is an octal digit. Octal digits are the character representations of the digits 0 to 7. 257 * 258 * @param ch the char to check 259 * @return true if the given char is the character representation of one of the digits from 0 to 7 260 * @since 3.18.0 261 */ 262 public static boolean isOctal(final char ch) { 263 return ch >= '0' && ch <= '7'; 264 } 265 266 /** 267 * Converts the Character to a char throwing an exception for {@code null}. 268 * 269 * <pre> 270 * CharUtils.toChar(' ') = ' ' 271 * CharUtils.toChar('A') = 'A' 272 * CharUtils.toChar(null) throws IllegalArgumentException 273 * </pre> 274 * 275 * @param ch the character to convert 276 * @return the char value of the Character 277 * @throws NullPointerException if the Character is null 278 */ 279 public static char toChar(final Character ch) { 280 return Objects.requireNonNull(ch, "ch").charValue(); 281 } 282 283 /** 284 * Converts the Character to a char handling {@code null}. 285 * 286 * <pre> 287 * CharUtils.toChar(null, 'X') = 'X' 288 * CharUtils.toChar(' ', 'X') = ' ' 289 * CharUtils.toChar('A', 'X') = 'A' 290 * </pre> 291 * 292 * @param ch the character to convert 293 * @param defaultValue the value to use if the Character is null 294 * @return the char value of the Character or the default if null 295 */ 296 public static char toChar(final Character ch, final char defaultValue) { 297 return ch != null ? ch.charValue() : defaultValue; 298 } 299 300 /** 301 * Converts the String to a char using the first character, throwing 302 * an exception on empty Strings. 303 * 304 * <pre> 305 * CharUtils.toChar("A") = 'A' 306 * CharUtils.toChar("BA") = 'B' 307 * CharUtils.toChar(null) throws IllegalArgumentException 308 * CharUtils.toChar("") throws IllegalArgumentException 309 * </pre> 310 * 311 * @param str the character to convert 312 * @return the char value of the first letter of the String 313 * @throws NullPointerException if the string is null 314 * @throws IllegalArgumentException if the String is empty 315 */ 316 public static char toChar(final String str) { 317 Validate.notEmpty(str, "The String must not be empty"); 318 return str.charAt(0); 319 } 320 321 /** 322 * Converts the String to a char using the first character, defaulting 323 * the value on empty Strings. 324 * 325 * <pre> 326 * CharUtils.toChar(null, 'X') = 'X' 327 * CharUtils.toChar("", 'X') = 'X' 328 * CharUtils.toChar("A", 'X') = 'A' 329 * CharUtils.toChar("BA", 'X') = 'B' 330 * </pre> 331 * 332 * @param str the character to convert 333 * @param defaultValue the value to use if the Character is null 334 * @return the char value of the first letter of the String or the default if null 335 */ 336 public static char toChar(final String str, final char defaultValue) { 337 return StringUtils.isEmpty(str) ? defaultValue : str.charAt(0); 338 } 339 340 /** 341 * Delegates to {@link Character#valueOf(char)}. 342 * 343 * @param c the character to convert 344 * @return a {@code Character} representing {@code c}. 345 * @deprecated Use {@link Character#valueOf(char)}. 346 */ 347 @Deprecated 348 public static Character toCharacterObject(final char c) { 349 return Character.valueOf(c); 350 } 351 352 /** 353 * Converts the String to a Character using the first character, returning 354 * null for empty Strings. 355 * 356 * <p>For ASCII 7 bit characters, this uses a cache that will return the 357 * same Character object each time.</p> 358 * 359 * <pre> 360 * CharUtils.toCharacterObject(null) = null 361 * CharUtils.toCharacterObject("") = null 362 * CharUtils.toCharacterObject("A") = 'A' 363 * CharUtils.toCharacterObject("BA") = 'B' 364 * </pre> 365 * 366 * @param str the character to convert 367 * @return the Character value of the first letter of the String 368 */ 369 public static Character toCharacterObject(final String str) { 370 return StringUtils.isEmpty(str) ? null : Character.valueOf(str.charAt(0)); 371 } 372 373 /** 374 * Converts the character to the Integer it represents, throwing an 375 * exception if the character is not numeric. 376 * 377 * <p>This method converts the char '1' to the int 1 and so on.</p> 378 * 379 * <pre> 380 * CharUtils.toIntValue('3') = 3 381 * CharUtils.toIntValue('A') throws IllegalArgumentException 382 * </pre> 383 * 384 * @param ch the character to convert 385 * @return the int value of the character 386 * @throws IllegalArgumentException if the character is not ASCII numeric 387 */ 388 public static int toIntValue(final char ch) { 389 if (!isAsciiNumeric(ch)) { 390 throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'"); 391 } 392 return ch - 48; 393 } 394 395 /** 396 * Converts the character to the Integer it represents, throwing an 397 * exception if the character is not numeric. 398 * 399 * <p>This method converts the char '1' to the int 1 and so on.</p> 400 * 401 * <pre> 402 * CharUtils.toIntValue('3', -1) = 3 403 * CharUtils.toIntValue('A', -1) = -1 404 * </pre> 405 * 406 * @param ch the character to convert 407 * @param defaultValue the default value to use if the character is not numeric 408 * @return the int value of the character 409 */ 410 public static int toIntValue(final char ch, final int defaultValue) { 411 return isAsciiNumeric(ch) ? ch - 48 : defaultValue; 412 } 413 414 /** 415 * Converts the character to the Integer it represents, throwing an 416 * exception if the character is not numeric. 417 * 418 * <p>This method converts the char '1' to the int 1 and so on.</p> 419 * 420 * <pre> 421 * CharUtils.toIntValue('3') = 3 422 * CharUtils.toIntValue(null) throws IllegalArgumentException 423 * CharUtils.toIntValue('A') throws IllegalArgumentException 424 * </pre> 425 * 426 * @param ch the character to convert, not null 427 * @return the int value of the character 428 * @throws NullPointerException if the Character is null 429 * @throws IllegalArgumentException if the Character is not ASCII numeric 430 */ 431 public static int toIntValue(final Character ch) { 432 return toIntValue(toChar(ch)); 433 } 434 435 /** 436 * Converts the character to the Integer it represents, throwing an 437 * exception if the character is not numeric. 438 * 439 * <p>This method converts the char '1' to the int 1 and so on.</p> 440 * 441 * <pre> 442 * CharUtils.toIntValue(null, -1) = -1 443 * CharUtils.toIntValue('3', -1) = 3 444 * CharUtils.toIntValue('A', -1) = -1 445 * </pre> 446 * 447 * @param ch the character to convert 448 * @param defaultValue the default value to use if the character is not numeric 449 * @return the int value of the character 450 */ 451 public static int toIntValue(final Character ch, final int defaultValue) { 452 return ch != null ? toIntValue(ch.charValue(), defaultValue) : defaultValue; 453 } 454 455 /** 456 * Converts the character to a String that contains the one character. 457 * 458 * <p>For ASCII 7 bit characters, this uses a cache that will return the 459 * same String object each time.</p> 460 * 461 * <pre> 462 * CharUtils.toString(' ') = " " 463 * CharUtils.toString('A') = "A" 464 * </pre> 465 * 466 * @param ch the character to convert 467 * @return a String containing the one specified character 468 */ 469 public static String toString(final char ch) { 470 if (ch < CHAR_STRING_ARRAY.length) { 471 return CHAR_STRING_ARRAY[ch]; 472 } 473 return String.valueOf(ch); 474 } 475 476 /** 477 * Converts the character to a String that contains the one character. 478 * 479 * <p>For ASCII 7 bit characters, this uses a cache that will return the 480 * same String object each time.</p> 481 * 482 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 483 * 484 * <pre> 485 * CharUtils.toString(null) = null 486 * CharUtils.toString(' ') = " " 487 * CharUtils.toString('A') = "A" 488 * </pre> 489 * 490 * @param ch the character to convert 491 * @return a String containing the one specified character 492 */ 493 public static String toString(final Character ch) { 494 return ch != null ? toString(ch.charValue()) : null; 495 } 496 497 /** 498 * Converts the string to the Unicode format '\u0020'. 499 * 500 * <p>This format is the Java source code format.</p> 501 * 502 * <pre> 503 * CharUtils.unicodeEscaped(' ') = "\u0020" 504 * CharUtils.unicodeEscaped('A') = "\u0041" 505 * </pre> 506 * 507 * @param ch the character to convert 508 * @return the escaped Unicode string 509 */ 510 public static String unicodeEscaped(final char ch) { 511 return "\\u" + 512 HEX_DIGITS[ch >> 12 & 15] + 513 HEX_DIGITS[ch >> 8 & 15] + 514 HEX_DIGITS[ch >> 4 & 15] + 515 HEX_DIGITS[ch & 15]; 516 } 517 518 /** 519 * Converts the string to the Unicode format '\u0020'. 520 * 521 * <p>This format is the Java source code format.</p> 522 * 523 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 524 * 525 * <pre> 526 * CharUtils.unicodeEscaped(null) = null 527 * CharUtils.unicodeEscaped(' ') = "\u0020" 528 * CharUtils.unicodeEscaped('A') = "\u0041" 529 * </pre> 530 * 531 * @param ch the character to convert, may be null 532 * @return the escaped Unicode string, null if null input 533 */ 534 public static String unicodeEscaped(final Character ch) { 535 return ch != null ? unicodeEscaped(ch.charValue()) : null; 536 } 537 538 /** 539 * {@link CharUtils} instances should NOT be constructed in standard programming. 540 * Instead, the class should be used as {@code CharUtils.toString('c');}. 541 * 542 * <p>This constructor is public to permit tools that require a JavaBean instance 543 * to operate.</p> 544 * 545 * @deprecated TODO Make private in 4.0. 546 */ 547 @Deprecated 548 public CharUtils() { 549 // empty 550 } 551}