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