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.isAsciiPrintable('0') = true 233 * CharUtils.isAsciiPrintable('9') = true 234 * CharUtils.isAsciiPrintable('a') = true 235 * CharUtils.isAsciiPrintable('f') = true 236 * CharUtils.isAsciiPrintable('g') = false 237 * CharUtils.isAsciiPrintable('A') = true 238 * CharUtils.isAsciiPrintable('F') = true 239 * CharUtils.isAsciiPrintable('G') = false 240 * CharUtils.isAsciiPrintable('3') = false 241 * CharUtils.isAsciiPrintable('-') = false 242 * CharUtils.isAsciiPrintable('\n') = false 243 * CharUtils.isAsciiPrintable('©') = false 244 * </pre> 245 * 246 * @param ch the character to test. 247 * @return true if character is a hexadecimal character. 248 * @since 3.18.0 249 */ 250 public static boolean isHex(final char ch) { 251 return isAsciiNumeric(ch) || ch >= 'a' && ch <= 'f' || ch >= 'A' && ch <= 'F'; 252 } 253 254 /** 255 * Tests if the given char is an octal digit. Octal digits are the character representations of the digits 0 to 7. 256 * 257 * @param ch the char to check 258 * @return true if the given char is the character representation of one of the digits from 0 to 7 259 * @since 3.18.0 260 */ 261 public static boolean isOctal(final char ch) { 262 return ch >= '0' && ch <= '7'; 263 } 264 265 /** 266 * Converts the Character to a char throwing an exception for {@code null}. 267 * 268 * <pre> 269 * CharUtils.toChar(' ') = ' ' 270 * CharUtils.toChar('A') = 'A' 271 * CharUtils.toChar(null) throws IllegalArgumentException 272 * </pre> 273 * 274 * @param ch the character to convert 275 * @return the char value of the Character 276 * @throws NullPointerException if the Character is null 277 */ 278 public static char toChar(final Character ch) { 279 return Objects.requireNonNull(ch, "ch").charValue(); 280 } 281 282 /** 283 * Converts the Character to a char handling {@code null}. 284 * 285 * <pre> 286 * CharUtils.toChar(null, 'X') = 'X' 287 * CharUtils.toChar(' ', 'X') = ' ' 288 * CharUtils.toChar('A', 'X') = 'A' 289 * </pre> 290 * 291 * @param ch the character to convert 292 * @param defaultValue the value to use if the Character is null 293 * @return the char value of the Character or the default if null 294 */ 295 public static char toChar(final Character ch, final char defaultValue) { 296 return ch != null ? ch.charValue() : defaultValue; 297 } 298 299 /** 300 * Converts the String to a char using the first character, throwing 301 * an exception on empty Strings. 302 * 303 * <pre> 304 * CharUtils.toChar("A") = 'A' 305 * CharUtils.toChar("BA") = 'B' 306 * CharUtils.toChar(null) throws IllegalArgumentException 307 * CharUtils.toChar("") throws IllegalArgumentException 308 * </pre> 309 * 310 * @param str the character to convert 311 * @return the char value of the first letter of the String 312 * @throws NullPointerException if the string is null 313 * @throws IllegalArgumentException if the String is empty 314 */ 315 public static char toChar(final String str) { 316 Validate.notEmpty(str, "The String must not be empty"); 317 return str.charAt(0); 318 } 319 320 /** 321 * Converts the String to a char using the first character, defaulting 322 * the value on empty Strings. 323 * 324 * <pre> 325 * CharUtils.toChar(null, 'X') = 'X' 326 * CharUtils.toChar("", 'X') = 'X' 327 * CharUtils.toChar("A", 'X') = 'A' 328 * CharUtils.toChar("BA", 'X') = 'B' 329 * </pre> 330 * 331 * @param str the character to convert 332 * @param defaultValue the value to use if the Character is null 333 * @return the char value of the first letter of the String or the default if null 334 */ 335 public static char toChar(final String str, final char defaultValue) { 336 return StringUtils.isEmpty(str) ? defaultValue : str.charAt(0); 337 } 338 339 /** 340 * Delegates to {@link Character#valueOf(char)}. 341 * 342 * @param c the character to convert 343 * @return a {@code Character} representing {@code c}. 344 * @deprecated Use {@link Character#valueOf(char)}. 345 */ 346 @Deprecated 347 public static Character toCharacterObject(final char c) { 348 return Character.valueOf(c); 349 } 350 351 /** 352 * Converts the String to a Character using the first character, returning 353 * null for empty Strings. 354 * 355 * <p>For ASCII 7 bit characters, this uses a cache that will return the 356 * same Character object each time.</p> 357 * 358 * <pre> 359 * CharUtils.toCharacterObject(null) = null 360 * CharUtils.toCharacterObject("") = null 361 * CharUtils.toCharacterObject("A") = 'A' 362 * CharUtils.toCharacterObject("BA") = 'B' 363 * </pre> 364 * 365 * @param str the character to convert 366 * @return the Character value of the first letter of the String 367 */ 368 public static Character toCharacterObject(final String str) { 369 return StringUtils.isEmpty(str) ? null : Character.valueOf(str.charAt(0)); 370 } 371 372 /** 373 * Converts the character to the Integer it represents, throwing an 374 * exception if the character is not numeric. 375 * 376 * <p>This method converts the char '1' to the int 1 and so on.</p> 377 * 378 * <pre> 379 * CharUtils.toIntValue('3') = 3 380 * CharUtils.toIntValue('A') throws IllegalArgumentException 381 * </pre> 382 * 383 * @param ch the character to convert 384 * @return the int value of the character 385 * @throws IllegalArgumentException if the character is not ASCII numeric 386 */ 387 public static int toIntValue(final char ch) { 388 if (!isAsciiNumeric(ch)) { 389 throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'"); 390 } 391 return ch - 48; 392 } 393 394 /** 395 * Converts the character to the Integer it represents, throwing an 396 * exception if the character is not numeric. 397 * 398 * <p>This method converts the char '1' to the int 1 and so on.</p> 399 * 400 * <pre> 401 * CharUtils.toIntValue('3', -1) = 3 402 * CharUtils.toIntValue('A', -1) = -1 403 * </pre> 404 * 405 * @param ch the character to convert 406 * @param defaultValue the default value to use if the character is not numeric 407 * @return the int value of the character 408 */ 409 public static int toIntValue(final char ch, final int defaultValue) { 410 return isAsciiNumeric(ch) ? ch - 48 : defaultValue; 411 } 412 413 /** 414 * Converts the character to the Integer it represents, throwing an 415 * exception if the character is not numeric. 416 * 417 * <p>This method converts the char '1' to the int 1 and so on.</p> 418 * 419 * <pre> 420 * CharUtils.toIntValue('3') = 3 421 * CharUtils.toIntValue(null) throws IllegalArgumentException 422 * CharUtils.toIntValue('A') throws IllegalArgumentException 423 * </pre> 424 * 425 * @param ch the character to convert, not null 426 * @return the int value of the character 427 * @throws NullPointerException if the Character is null 428 * @throws IllegalArgumentException if the Character is not ASCII numeric 429 */ 430 public static int toIntValue(final Character ch) { 431 return toIntValue(toChar(ch)); 432 } 433 434 /** 435 * Converts the character to the Integer it represents, throwing an 436 * exception if the character is not numeric. 437 * 438 * <p>This method converts the char '1' to the int 1 and so on.</p> 439 * 440 * <pre> 441 * CharUtils.toIntValue(null, -1) = -1 442 * CharUtils.toIntValue('3', -1) = 3 443 * CharUtils.toIntValue('A', -1) = -1 444 * </pre> 445 * 446 * @param ch the character to convert 447 * @param defaultValue the default value to use if the character is not numeric 448 * @return the int value of the character 449 */ 450 public static int toIntValue(final Character ch, final int defaultValue) { 451 return ch != null ? toIntValue(ch.charValue(), defaultValue) : defaultValue; 452 } 453 454 /** 455 * Converts the character to a String that contains the one character. 456 * 457 * <p>For ASCII 7 bit characters, this uses a cache that will return the 458 * same String object each time.</p> 459 * 460 * <pre> 461 * CharUtils.toString(' ') = " " 462 * CharUtils.toString('A') = "A" 463 * </pre> 464 * 465 * @param ch the character to convert 466 * @return a String containing the one specified character 467 */ 468 public static String toString(final char ch) { 469 if (ch < CHAR_STRING_ARRAY.length) { 470 return CHAR_STRING_ARRAY[ch]; 471 } 472 return String.valueOf(ch); 473 } 474 475 /** 476 * Converts the character to a String that contains the one character. 477 * 478 * <p>For ASCII 7 bit characters, this uses a cache that will return the 479 * same String object each time.</p> 480 * 481 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 482 * 483 * <pre> 484 * CharUtils.toString(null) = null 485 * CharUtils.toString(' ') = " " 486 * CharUtils.toString('A') = "A" 487 * </pre> 488 * 489 * @param ch the character to convert 490 * @return a String containing the one specified character 491 */ 492 public static String toString(final Character ch) { 493 return ch != null ? toString(ch.charValue()) : null; 494 } 495 496 /** 497 * Converts the string to the Unicode format '\u0020'. 498 * 499 * <p>This format is the Java source code format.</p> 500 * 501 * <pre> 502 * CharUtils.unicodeEscaped(' ') = "\u0020" 503 * CharUtils.unicodeEscaped('A') = "\u0041" 504 * </pre> 505 * 506 * @param ch the character to convert 507 * @return the escaped Unicode string 508 */ 509 public static String unicodeEscaped(final char ch) { 510 return "\\u" + 511 HEX_DIGITS[ch >> 12 & 15] + 512 HEX_DIGITS[ch >> 8 & 15] + 513 HEX_DIGITS[ch >> 4 & 15] + 514 HEX_DIGITS[ch & 15]; 515 } 516 517 /** 518 * Converts the string to the Unicode format '\u0020'. 519 * 520 * <p>This format is the Java source code format.</p> 521 * 522 * <p>If {@code null} is passed in, {@code null} will be returned.</p> 523 * 524 * <pre> 525 * CharUtils.unicodeEscaped(null) = null 526 * CharUtils.unicodeEscaped(' ') = "\u0020" 527 * CharUtils.unicodeEscaped('A') = "\u0041" 528 * </pre> 529 * 530 * @param ch the character to convert, may be null 531 * @return the escaped Unicode string, null if null input 532 */ 533 public static String unicodeEscaped(final Character ch) { 534 return ch != null ? unicodeEscaped(ch.charValue()) : null; 535 } 536 537 /** 538 * {@link CharUtils} instances should NOT be constructed in standard programming. 539 * Instead, the class should be used as {@code CharUtils.toString('c');}. 540 * 541 * <p>This constructor is public to permit tools that require a JavaBean instance 542 * to operate.</p> 543 * 544 * @deprecated TODO Make private in 4.0. 545 */ 546 @Deprecated 547 public CharUtils() { 548 // empty 549 } 550}