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 * http://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 = new String[128];
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 static {
63 ArrayUtils.setAll(CHAR_STRING_ARRAY, i -> String.valueOf((char) i));
64 }
65
66 /**
67 * Compares two {@code char} values numerically. This is the same functionality as provided in Java 7.
68 *
69 * @param x the first {@code char} to compare
70 * @param y the second {@code char} to compare
71 * @return the value {@code 0} if {@code x == y};
72 * a value less than {@code 0} if {@code x < y}; and
73 * a value greater than {@code 0} if {@code x > y}
74 * @since 3.4
75 */
76 public static int compare(final char x, final char y) {
77 return x - y;
78 }
79
80 /**
81 * Checks whether the character is ASCII 7 bit.
82 *
83 * <pre>
84 * CharUtils.isAscii('a') = true
85 * CharUtils.isAscii('A') = true
86 * CharUtils.isAscii('3') = true
87 * CharUtils.isAscii('-') = true
88 * CharUtils.isAscii('\n') = true
89 * CharUtils.isAscii('©') = false
90 * </pre>
91 *
92 * @param ch the character to check
93 * @return true if less than 128
94 */
95 public static boolean isAscii(final char ch) {
96 return ch < 128;
97 }
98
99 /**
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 }