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 * 030 * @since 2.1 031 */ 032public class CharUtils { 033 034 private static final String[] CHAR_STRING_ARRAY = ArrayUtils.setAll(new String[128], i -> String.valueOf((char) i)); 035 036 private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}; 037 038 /** 039 * Linefeed character LF ({@code '\n'}, Unicode 000a). 040 * 041 * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences 042 * for Character and String Literals</a> 043 * @since 2.2 044 */ 045 public static final char LF = '\n'; 046 047 /** 048 * Carriage return character CR ('\r', Unicode 000d). 049 * 050 * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences 051 * for Character and String Literals</a> 052 * @since 2.2 053 */ 054 public static final char CR = '\r'; 055 056 /** 057 * {@code \u0000} null control character ('\0'), abbreviated NUL. 058 * 059 * @since 3.6 060 */ 061 public static final char NUL = '\0'; 062 063 /** 064 * Compares two {@code char} values numerically. This is the same functionality as provided in Java 7. 065 * 066 * @param x the first {@code char} to compare 067 * @param y the second {@code char} to compare 068 * @return the value {@code 0} if {@code x == y}; 069 * a value less than {@code 0} if {@code x < y}; and 070 * a value greater than {@code 0} if {@code x > y} 071 * @since 3.4 072 */ 073 public static int compare(final char x, final char y) { 074 return x - y; 075 } 076 077 /** 078 * Tests whether the character is ASCII 7 bit. 079 * 080 * <pre> 081 * CharUtils.isAscii('a') = true 082 * CharUtils.isAscii('A') = true 083 * CharUtils.isAscii('3') = true 084 * CharUtils.isAscii('-') = true 085 * CharUtils.isAscii('\n') = true 086 * CharUtils.isAscii('©') = false 087 * </pre> 088 * 089 * @param ch the character to check 090 * @return true if less than 128 091 */ 092 public static boolean isAscii(final char ch) { 093 return ch < 128; 094 } 095 096 /** 097 * Tests whether the character is ASCII 7 bit alphabetic. 098 * 099 * <pre> 100 * CharUtils.isAsciiAlpha('a') = true 101 * CharUtils.isAsciiAlpha('A') = true 102 * CharUtils.isAsciiAlpha('3') = false 103 * CharUtils.isAsciiAlpha('-') = false 104 * CharUtils.isAsciiAlpha('\n') = false 105 * CharUtils.isAsciiAlpha('©') = false 106 * </pre> 107 * 108 * @param ch the character to check 109 * @return true if between 65 and 90 or 97 and 122 inclusive 110 */ 111 public static boolean isAsciiAlpha(final char ch) { 112 return isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch); 113 } 114 115 /** 116 * Tests whether the character is ASCII 7 bit alphabetic lower case. 117 * 118 * <pre> 119 * CharUtils.isAsciiAlphaLower('a') = true 120 * CharUtils.isAsciiAlphaLower('A') = false 121 * CharUtils.isAsciiAlphaLower('3') = false 122 * CharUtils.isAsciiAlphaLower('-') = false 123 * CharUtils.isAsciiAlphaLower('\n') = false 124 * CharUtils.isAsciiAlphaLower('©') = false 125 * </pre> 126 * 127 * @param ch the character to check 128 * @return true if between 97 and 122 inclusive 129 */ 130 public static boolean isAsciiAlphaLower(final char ch) { 131 return ch >= 'a' && ch <= 'z'; 132 } 133 134 /** 135 * Tests whether the character is ASCII 7 bit alphanumeric character. 136 * 137 * <pre> 138 * CharUtils.isAsciiAlphanumeric('a') = true 139 * CharUtils.isAsciiAlphanumeric('A') = true 140 * CharUtils.isAsciiAlphanumeric('3') = true 141 * CharUtils.isAsciiAlphanumeric('-') = false 142 * CharUtils.isAsciiAlphanumeric('\n') = false 143 * CharUtils.isAsciiAlphanumeric('©') = false 144 * </pre> 145 * 146 * @param ch the character to check 147 * @return true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive 148 */ 149 public static boolean isAsciiAlphanumeric(final char ch) { 150 return isAsciiAlpha(ch) || isAsciiNumeric(ch); 151 } 152 153 /** 154 * Tests whether the character is ASCII 7 bit alphabetic upper case. 155 * 156 * <pre> 157 * CharUtils.isAsciiAlphaUpper('a') = false 158 * CharUtils.isAsciiAlphaUpper('A') = true 159 * CharUtils.isAsciiAlphaUpper('3') = false 160 * CharUtils.isAsciiAlphaUpper('-') = false 161 * CharUtils.isAsciiAlphaUpper('\n') = false 162 * CharUtils.isAsciiAlphaUpper('©') = false 163 * </pre> 164 * 165 * @param ch the character to check 166 * @return true if between 65 and 90 inclusive 167 */ 168 public static boolean isAsciiAlphaUpper(final char ch) { 169 return ch >= 'A' && ch <= 'Z'; 170 } 171 172 /** 173 * Tests whether the character is ASCII 7 bit control. 174 * 175 * <pre> 176 * CharUtils.isAsciiControl('a') = false 177 * CharUtils.isAsciiControl('A') = false 178 * CharUtils.isAsciiControl('3') = false 179 * CharUtils.isAsciiControl('-') = false 180 * CharUtils.isAsciiControl('\n') = true 181 * CharUtils.isAsciiControl('©') = false 182 * </pre> 183 * 184 * @param ch the character to check 185 * @return true if less than 32 or equals 127 186 */ 187 public static boolean isAsciiControl(final char ch) { 188 return ch < 32 || ch == 127; 189 } 190 191 /** 192 * Tests whether the character is ASCII 7 bit numeric. 193 * 194 * <pre> 195 * CharUtils.isAsciiNumeric('a') = false 196 * CharUtils.isAsciiNumeric('A') = false 197 * CharUtils.isAsciiNumeric('3') = true 198 * CharUtils.isAsciiNumeric('-') = false 199 * CharUtils.isAsciiNumeric('\n') = false 200 * CharUtils.isAsciiNumeric('©') = false 201 * </pre> 202 * 203 * @param ch the character to check 204 * @return true if between 48 and 57 inclusive 205 */ 206 public static boolean isAsciiNumeric(final char ch) { 207 return ch >= '0' && ch <= '9'; 208 } 209 210 /** 211 * Tests whether the character is ASCII 7 bit printable. 212 * 213 * <pre> 214 * CharUtils.isAsciiPrintable('a') = true 215 * CharUtils.isAsciiPrintable('A') = true 216 * CharUtils.isAsciiPrintable('3') = true 217 * CharUtils.isAsciiPrintable('-') = true 218 * CharUtils.isAsciiPrintable('\n') = false 219 * CharUtils.isAsciiPrintable('©') = false 220 * </pre> 221 * 222 * @param ch the character to check 223 * @return true if between 32 and 126 inclusive 224 */ 225 public static boolean isAsciiPrintable(final char ch) { 226 return ch >= 32 && ch < 127; 227 } 228 229 /** 230 * Tests whether a character is a hexadecimal character. 231 * 232 * <pre> 233 * CharUtils.isHex('0') = true 234 * CharUtils.isHex('3') = true 235 * CharUtils.isHex('9') = true 236 * CharUtils.isHex('a') = true 237 * CharUtils.isHex('f') = true 238 * CharUtils.isHex('g') = false 239 * CharUtils.isHex('A') = true 240 * CharUtils.isHex('F') = true 241 * CharUtils.isHex('G') = false 242 * CharUtils.isHex('#') = false 243 * CharUtils.isHex('-') = false 244 * CharUtils.isHex('\n') = false 245 * CharUtils.isHex('©') = false 246 * </pre> 247 * 248 * @param ch the character to test. 249 * @return true if character is a hexadecimal character. 250 * @since 3.18.0 251 */ 252 public static boolean isHex(final char ch) { 253 return isAsciiNumeric(ch) || ch >= 'a' && ch <= 'f' || ch >= 'A' && ch <= 'F'; 254 } 255 256 /** 257 * Tests if the given char is an octal digit. Octal digits are the character representations of the digits 0 to 7. 258 * 259 * @param ch the char to check 260 * @return true if the given char is the character representation of one of the digits from 0 to 7 261 * @since 3.18.0 262 */ 263 public static boolean isOctal(final char ch) { 264 return ch >= '0' && ch <= '7'; 265 } 266 267 /** 268 * Converts the Character to a char throwing an exception for {@code null}. 269 * 270 * <pre> 271 * CharUtils.toChar(' ') = ' ' 272 * CharUtils.toChar('A') = 'A' 273 * CharUtils.toChar(null) throws NullPointerException 274 * </pre> 275 * 276 * @param ch the character to convert 277 * @return the char value of the Character 278 * @throws NullPointerException if the Character is null 279 */ 280 public static char toChar(final Character ch) { 281 return Objects.requireNonNull(ch, "ch").charValue(); 282 } 283 284 /** 285 * Converts the Character to a char handling {@code null}. 286 * 287 * <pre> 288 * CharUtils.toChar(null, 'X') = 'X' 289 * CharUtils.toChar(' ', 'X') = ' ' 290 * CharUtils.toChar('A', 'X') = 'A' 291 * </pre> 292 * 293 * @param ch the character to convert 294 * @param defaultValue the value to use if the Character is null 295 * @return the char value of the Character or the default if null 296 */ 297 public static char toChar(final Character ch, final char defaultValue) { 298 return ch != null ? ch.charValue() : defaultValue; 299 } 300 301 /** 302 * Converts the String to a char using the first character, throwing 303 * an exception on empty Strings. 304 * 305 * <pre> 306 * CharUtils.toChar("A") = 'A' 307 * CharUtils.toChar("BA") = 'B' 308 * CharUtils.toChar(null) throws NullPointerException 309 * CharUtils.toChar("") throws IllegalArgumentException 310 * </pre> 311 * 312 * @param str the character to convert 313 * @return the char value of the first letter of the String 314 * @throws NullPointerException if the string is null 315 * @throws IllegalArgumentException if the String is empty 316 */ 317 public static char toChar(final String str) { 318 Validate.notEmpty(str, "The String must not be empty"); 319 return str.charAt(0); 320 } 321 322 /** 323 * Converts the String to a char using the first character, defaulting 324 * the value on empty Strings. 325 * 326 * <pre> 327 * CharUtils.toChar(null, 'X') = 'X' 328 * CharUtils.toChar("", 'X') = 'X' 329 * CharUtils.toChar("A", 'X') = 'A' 330 * CharUtils.toChar("BA", 'X') = 'B' 331 * </pre> 332 * 333 * @param str the character to convert 334 * @param defaultValue the value to use if the Character is null 335 * @return the char value of the first letter of the String or the default if null 336 */ 337 public static char toChar(final String str, final char defaultValue) { 338 return StringUtils.isEmpty(str) ? defaultValue : str.charAt(0); 339 } 340 341 /** 342 * Delegates to {@link Character#valueOf(char)}. 343 * 344 * @param c the character to convert 345 * @return a {@code Character} representing {@code c}. 346 * @deprecated Use {@link Character#valueOf(char)}. 347 */ 348 @Deprecated 349 public static Character toCharacterObject(final char c) { 350 return Character.valueOf(c); 351 } 352 353 /** 354 * Converts the String to a Character using the first character, returning 355 * null for empty Strings. 356 * 357 * <p>For ASCII 7 bit characters, this uses a cache that will return the 358 * same Character object each time.</p> 359 * 360 * <pre> 361 * CharUtils.toCharacterObject(null) = null 362 * CharUtils.toCharacterObject("") = null 363 * CharUtils.toCharacterObject("A") = 'A' 364 * CharUtils.toCharacterObject("BA") = 'B' 365 * </pre> 366 * 367 * @param str the character to convert 368 * @return the Character value of the first letter of the String 369 */ 370 public static Character toCharacterObject(final String str) { 371 return StringUtils.isEmpty(str) ? null : Character.valueOf(str.charAt(0)); 372 } 373 374 /** 375 * Converts the character to the Integer it represents, throwing an 376 * exception if the character is not numeric. 377 * 378 * <p>This method converts the char '1' to the int 1 and so on.</p> 379 * 380 * <pre> 381 * CharUtils.toIntValue('3') = 3 382 * CharUtils.toIntValue('A') throws IllegalArgumentException 383 * </pre> 384 * 385 * @param ch the character to convert 386 * @return the int value of the character 387 * @throws IllegalArgumentException if the character is not ASCII numeric 388 */ 389 public static int toIntValue(final char ch) { 390 if (!isAsciiNumeric(ch)) { 391 throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'"); 392 } 393 return ch - 48; 394 } 395 396 /** 397 * Converts the character to the Integer it represents, throwing an 398 * exception if the character is not numeric. 399 * 400 * <p>This method converts the char '1' to the int 1 and so on.</p> 401 * 402 * <pre> 403 * CharUtils.toIntValue('3', -1) = 3 404 * CharUtils.toIntValue('A', -1) = -1 405 * </pre> 406 * 407 * @param ch the character to convert 408 * @param defaultValue the default value to use if the character is not numeric 409 * @return the int value of the character 410 */ 411 public static int toIntValue(final char ch, final int defaultValue) { 412 return isAsciiNumeric(ch) ? ch - 48 : defaultValue; 413 } 414 415 /** 416 * Converts the character to the Integer it represents, throwing an 417 * exception if the character is not numeric. 418 * 419 * <p>This method converts the char '1' to the int 1 and so on.</p> 420 * 421 * <pre> 422 * CharUtils.toIntValue('3') = 3 423 * CharUtils.toIntValue(null) throws NullPointerException 424 * CharUtils.toIntValue('A') throws IllegalArgumentException 425 * </pre> 426 * 427 * @param ch the character to convert, not null 428 * @return the int value of the character 429 * @throws NullPointerException if the Character is null 430 * @throws IllegalArgumentException if the Character is not ASCII numeric 431 */ 432 public static int toIntValue(final Character ch) { 433 return toIntValue(toChar(ch)); 434 } 435 436 /** 437 * Converts the character to the Integer it represents, throwing an 438 * exception if the character is not numeric. 439 * 440 * <p>This method converts the char '1' to the int 1 and so on.</p> 441 * 442 * <pre> 443 * CharUtils.toIntValue(null, -1) = -1 444 * CharUtils.toIntValue('3', -1) = 3 445 * CharUtils.toIntValue('A', -1) = -1 446 * </pre> 447 * 448 * @param ch the character to convert 449 * @param defaultValue the default value to use if the character is not numeric 450 * @return the int value of the character 451 */ 452 public static int toIntValue(final Character ch, final int defaultValue) { 453 return ch != null ? toIntValue(ch.charValue(), defaultValue) : defaultValue; 454 } 455 456 /** 457 * Converts the character to a String that contains the one character. 458 * 459 * <p>For ASCII 7 bit characters, this uses a cache that will return the 460 * same String object each time.</p> 461 * 462 * <pre> 463 * CharUtils.toString(' ') = " " 464 * CharUtils.toString('A') = "A" 465 * </pre> 466 * 467 * @param ch the character to convert 468 * @return a String containing the one specified character 469 */ 470 public static String toString(final char ch) { 471 if (ch < CHAR_STRING_ARRAY.length) { 472 return CHAR_STRING_ARRAY[ch]; 473 } 474 return String.valueOf(ch); 475 } 476 477 /** 478 * Converts the character to a String that contains the one character. 479 * 480 * <p>For ASCII 7 bit characters, this uses a cache that will return the 481 * same String object each time.</p> 482 * 483 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 484 * 485 * <pre> 486 * CharUtils.toString(null) = null 487 * CharUtils.toString(' ') = " " 488 * CharUtils.toString('A') = "A" 489 * </pre> 490 * 491 * @param ch the character to convert 492 * @return a String containing the one specified character 493 */ 494 public static String toString(final Character ch) { 495 return ch != null ? toString(ch.charValue()) : null; 496 } 497 498 /** 499 * Converts the string to the Unicode format '\u0020'. 500 * 501 * <p>This format is the Java source code format.</p> 502 * 503 * <pre> 504 * CharUtils.unicodeEscaped(' ') = "\u0020" 505 * CharUtils.unicodeEscaped('A') = "\u0041" 506 * </pre> 507 * 508 * @param ch the character to convert 509 * @return the escaped Unicode string 510 */ 511 public static String unicodeEscaped(final char ch) { 512 return "\\u" + 513 HEX_DIGITS[ch >> 12 & 15] + 514 HEX_DIGITS[ch >> 8 & 15] + 515 HEX_DIGITS[ch >> 4 & 15] + 516 HEX_DIGITS[ch & 15]; 517 } 518 519 /** 520 * Converts the string to the Unicode format '\u0020'. 521 * 522 * <p>This format is the Java source code format.</p> 523 * 524 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 525 * 526 * <pre> 527 * CharUtils.unicodeEscaped(null) = null 528 * CharUtils.unicodeEscaped(' ') = "\u0020" 529 * CharUtils.unicodeEscaped('A') = "\u0041" 530 * </pre> 531 * 532 * @param ch the character to convert, may be null 533 * @return the escaped Unicode string, null if null input 534 */ 535 public static String unicodeEscaped(final Character ch) { 536 return ch != null ? unicodeEscaped(ch.charValue()) : null; 537 } 538 539 /** 540 * {@link CharUtils} instances should NOT be constructed in standard programming. 541 * Instead, the class should be used as {@code CharUtils.toString('c');}. 542 * 543 * <p>This constructor is public to permit tools that require a JavaBean instance 544 * to operate.</p> 545 * 546 * @deprecated TODO Make private in 4.0. 547 */ 548 @Deprecated 549 public CharUtils() { 550 // empty 551 } 552}