1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.lang3;
18
19 import java.util.Objects;
20
21 /**
22 * Operations on char primitives and Character objects.
23 *
24 * <p>This class tries to handle {@code null} input gracefully.
25 * An exception will not be thrown for a {@code null} input.
26 * Each method documents its behavior in more detail.</p>
27 *
28 * <p>#ThreadSafe#</p>
29 * @since 2.1
30 */
31 public class CharUtils {
32
33 private static final String[] CHAR_STRING_ARRAY = ArrayUtils.setAll(new String[128], i -> String.valueOf((char) i));
34
35 private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
36
37 /**
38 * Linefeed character LF ({@code '\n'}, Unicode 000a).
39 *
40 * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences
41 * for Character and String Literals</a>
42 * @since 2.2
43 */
44 public static final char LF = '\n';
45
46 /**
47 * Carriage return character CR ('\r', Unicode 000d).
48 *
49 * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences
50 * for Character and String Literals</a>
51 * @since 2.2
52 */
53 public static final char CR = '\r';
54
55 /**
56 * {@code \u0000} null control character ('\0'), abbreviated NUL.
57 *
58 * @since 3.6
59 */
60 public static final char NUL = '\0';
61
62 /**
63 * Compares two {@code char} values numerically. This is the same functionality as provided in Java 7.
64 *
65 * @param x the first {@code char} to compare
66 * @param y the second {@code char} to compare
67 * @return the value {@code 0} if {@code x == y};
68 * a value less than {@code 0} if {@code x < y}; and
69 * a value greater than {@code 0} if {@code x > y}
70 * @since 3.4
71 */
72 public static int compare(final char x, final char y) {
73 return x - y;
74 }
75
76 /**
77 * Tests whether the character is ASCII 7 bit.
78 *
79 * <pre>
80 * CharUtils.isAscii('a') = true
81 * CharUtils.isAscii('A') = true
82 * CharUtils.isAscii('3') = true
83 * CharUtils.isAscii('-') = true
84 * CharUtils.isAscii('\n') = true
85 * CharUtils.isAscii('©') = false
86 * </pre>
87 *
88 * @param ch the character to check
89 * @return true if less than 128
90 */
91 public static boolean isAscii(final char ch) {
92 return ch < 128;
93 }
94
95 /**
96 * Tests whether the character is ASCII 7 bit alphabetic.
97 *
98 * <pre>
99 * 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 }