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Diffstat (limited to 'src/main/java/org/apache/commons/lang3/CharUtils.java')
| -rw-r--r-- | src/main/java/org/apache/commons/lang3/CharUtils.java | 521 |
1 files changed, 521 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/lang3/CharUtils.java b/src/main/java/org/apache/commons/lang3/CharUtils.java new file mode 100644 index 000000000..52b864d6e --- /dev/null +++ b/src/main/java/org/apache/commons/lang3/CharUtils.java @@ -0,0 +1,521 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.commons.lang3; + +import java.util.Objects; + +/** + * Operations on char primitives and Character objects. + * + * <p>This class tries to handle {@code null} input gracefully. + * An exception will not be thrown for a {@code null} input. + * Each method documents its behavior in more detail.</p> + * + * <p>#ThreadSafe#</p> + * @since 2.1 + */ +public class CharUtils { + + private static final String[] CHAR_STRING_ARRAY = new String[128]; + + private static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'}; + + /** + * Linefeed character LF ({@code '\n'}, Unicode 000a). + * + * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences + * for Character and String Literals</a> + * @since 2.2 + */ + public static final char LF = '\n'; + + /** + * Carriage return character CR ('\r', Unicode 000d). + * + * @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.6">JLF: Escape Sequences + * for Character and String Literals</a> + * @since 2.2 + */ + public static final char CR = '\r'; + + /** + * {@code \u0000} null control character ('\0'), abbreviated NUL. + * + * @since 3.6 + */ + public static final char NUL = '\0'; + + static { + ArrayUtils.setAll(CHAR_STRING_ARRAY, i -> String.valueOf((char) i)); + } + + /** + * {@link CharUtils} instances should NOT be constructed in standard programming. + * Instead, the class should be used as {@code CharUtils.toString('c');}. + * + * <p>This constructor is public to permit tools that require a JavaBean instance + * to operate.</p> + */ + public CharUtils() { + } + + /** + * Converts the character to a Character. + * + * <p>For ASCII 7 bit characters, this uses a cache that will return the + * same Character object each time.</p> + * + * <pre> + * CharUtils.toCharacterObject(' ') = ' ' + * CharUtils.toCharacterObject('A') = 'A' + * </pre> + * + * @deprecated Java 5 introduced {@link Character#valueOf(char)} which caches chars 0 through 127. + * @param ch the character to convert + * @return a Character of the specified character + */ + @Deprecated + public static Character toCharacterObject(final char ch) { + return Character.valueOf(ch); + } + + /** + * Converts the String to a Character using the first character, returning + * null for empty Strings. + * + * <p>For ASCII 7 bit characters, this uses a cache that will return the + * same Character object each time.</p> + * + * <pre> + * CharUtils.toCharacterObject(null) = null + * CharUtils.toCharacterObject("") = null + * CharUtils.toCharacterObject("A") = 'A' + * CharUtils.toCharacterObject("BA") = 'B' + * </pre> + * + * @param str the character to convert + * @return the Character value of the first letter of the String + */ + public static Character toCharacterObject(final String str) { + return StringUtils.isEmpty(str) ? null : Character.valueOf(str.charAt(0)); + } + + /** + * Converts the Character to a char throwing an exception for {@code null}. + * + * <pre> + * CharUtils.toChar(' ') = ' ' + * CharUtils.toChar('A') = 'A' + * CharUtils.toChar(null) throws IllegalArgumentException + * </pre> + * + * @param ch the character to convert + * @return the char value of the Character + * @throws NullPointerException if the Character is null + */ + public static char toChar(final Character ch) { + return Objects.requireNonNull(ch, "ch").charValue(); + } + + /** + * Converts the Character to a char handling {@code null}. + * + * <pre> + * CharUtils.toChar(null, 'X') = 'X' + * CharUtils.toChar(' ', 'X') = ' ' + * CharUtils.toChar('A', 'X') = 'A' + * </pre> + * + * @param ch the character to convert + * @param defaultValue the value to use if the Character is null + * @return the char value of the Character or the default if null + */ + public static char toChar(final Character ch, final char defaultValue) { + return ch != null ? ch.charValue() : defaultValue; + } + + /** + * Converts the String to a char using the first character, throwing + * an exception on empty Strings. + * + * <pre> + * CharUtils.toChar("A") = 'A' + * CharUtils.toChar("BA") = 'B' + * CharUtils.toChar(null) throws IllegalArgumentException + * CharUtils.toChar("") throws IllegalArgumentException + * </pre> + * + * @param str the character to convert + * @return the char value of the first letter of the String + * @throws NullPointerException if the string is null + * @throws IllegalArgumentException if the String is empty + */ + public static char toChar(final String str) { + Validate.notEmpty(str, "The String must not be empty"); + return str.charAt(0); + } + + /** + * Converts the String to a char using the first character, defaulting + * the value on empty Strings. + * + * <pre> + * CharUtils.toChar(null, 'X') = 'X' + * CharUtils.toChar("", 'X') = 'X' + * CharUtils.toChar("A", 'X') = 'A' + * CharUtils.toChar("BA", 'X') = 'B' + * </pre> + * + * @param str the character to convert + * @param defaultValue the value to use if the Character is null + * @return the char value of the first letter of the String or the default if null + */ + public static char toChar(final String str, final char defaultValue) { + return StringUtils.isEmpty(str) ? defaultValue : str.charAt(0); + } + + /** + * Converts the character to the Integer it represents, throwing an + * exception if the character is not numeric. + * + * <p>This method converts the char '1' to the int 1 and so on.</p> + * + * <pre> + * CharUtils.toIntValue('3') = 3 + * CharUtils.toIntValue('A') throws IllegalArgumentException + * </pre> + * + * @param ch the character to convert + * @return the int value of the character + * @throws IllegalArgumentException if the character is not ASCII numeric + */ + public static int toIntValue(final char ch) { + if (!isAsciiNumeric(ch)) { + throw new IllegalArgumentException("The character " + ch + " is not in the range '0' - '9'"); + } + return ch - 48; + } + + /** + * Converts the character to the Integer it represents, throwing an + * exception if the character is not numeric. + * + * <p>This method converts the char '1' to the int 1 and so on.</p> + * + * <pre> + * CharUtils.toIntValue('3', -1) = 3 + * CharUtils.toIntValue('A', -1) = -1 + * </pre> + * + * @param ch the character to convert + * @param defaultValue the default value to use if the character is not numeric + * @return the int value of the character + */ + public static int toIntValue(final char ch, final int defaultValue) { + return isAsciiNumeric(ch) ? ch - 48 : defaultValue; + } + + /** + * Converts the character to the Integer it represents, throwing an + * exception if the character is not numeric. + * + * <p>This method converts the char '1' to the int 1 and so on.</p> + * + * <pre> + * CharUtils.toIntValue('3') = 3 + * CharUtils.toIntValue(null) throws IllegalArgumentException + * CharUtils.toIntValue('A') throws IllegalArgumentException + * </pre> + * + * @param ch the character to convert, not null + * @return the int value of the character + * @throws NullPointerException if the Character is null + * @throws IllegalArgumentException if the Character is not ASCII numeric + */ + public static int toIntValue(final Character ch) { + return toIntValue(toChar(ch)); + } + + /** + * Converts the character to the Integer it represents, throwing an + * exception if the character is not numeric. + * + * <p>This method converts the char '1' to the int 1 and so on.</p> + * + * <pre> + * CharUtils.toIntValue(null, -1) = -1 + * CharUtils.toIntValue('3', -1) = 3 + * CharUtils.toIntValue('A', -1) = -1 + * </pre> + * + * @param ch the character to convert + * @param defaultValue the default value to use if the character is not numeric + * @return the int value of the character + */ + public static int toIntValue(final Character ch, final int defaultValue) { + return ch != null ? toIntValue(ch.charValue(), defaultValue) : defaultValue; + } + + /** + * Converts the character to a String that contains the one character. + * + * <p>For ASCII 7 bit characters, this uses a cache that will return the + * same String object each time.</p> + * + * <pre> + * CharUtils.toString(' ') = " " + * CharUtils.toString('A') = "A" + * </pre> + * + * @param ch the character to convert + * @return a String containing the one specified character + */ + public static String toString(final char ch) { + if (ch < CHAR_STRING_ARRAY.length) { + return CHAR_STRING_ARRAY[ch]; + } + return String.valueOf(ch); + } + + /** + * Converts the character to a String that contains the one character. + * + * <p>For ASCII 7 bit characters, this uses a cache that will return the + * same String object each time.</p> + * + * <p>If {@code null} is passed in, {@code null} will be returned.</p> + * + * <pre> + * CharUtils.toString(null) = null + * CharUtils.toString(' ') = " " + * CharUtils.toString('A') = "A" + * </pre> + * + * @param ch the character to convert + * @return a String containing the one specified character + */ + public static String toString(final Character ch) { + return ch != null ? toString(ch.charValue()) : null; + } + + /** + * Converts the string to the Unicode format '\u0020'. + * + * <p>This format is the Java source code format.</p> + * + * <pre> + * CharUtils.unicodeEscaped(' ') = "\u0020" + * CharUtils.unicodeEscaped('A') = "\u0041" + * </pre> + * + * @param ch the character to convert + * @return the escaped Unicode string + */ + public static String unicodeEscaped(final char ch) { + return "\\u" + + HEX_DIGITS[(ch >> 12) & 15] + + HEX_DIGITS[(ch >> 8) & 15] + + HEX_DIGITS[(ch >> 4) & 15] + + HEX_DIGITS[(ch) & 15]; + } + + /** + * Converts the string to the Unicode format '\u0020'. + * + * <p>This format is the Java source code format.</p> + * + * <p>If {@code null} is passed in, {@code null} will be returned.</p> + * + * <pre> + * CharUtils.unicodeEscaped(null) = null + * CharUtils.unicodeEscaped(' ') = "\u0020" + * CharUtils.unicodeEscaped('A') = "\u0041" + * </pre> + * + * @param ch the character to convert, may be null + * @return the escaped Unicode string, null if null input + */ + public static String unicodeEscaped(final Character ch) { + return ch != null ? unicodeEscaped(ch.charValue()) : null; + } + + /** + * Checks whether the character is ASCII 7 bit. + * + * <pre> + * CharUtils.isAscii('a') = true + * CharUtils.isAscii('A') = true + * CharUtils.isAscii('3') = true + * CharUtils.isAscii('-') = true + * CharUtils.isAscii('\n') = true + * CharUtils.isAscii('©') = false + * </pre> + * + * @param ch the character to check + * @return true if less than 128 + */ + public static boolean isAscii(final char ch) { + return ch < 128; + } + + /** + * Checks whether the character is ASCII 7 bit printable. + * + * <pre> + * CharUtils.isAsciiPrintable('a') = true + * CharUtils.isAsciiPrintable('A') = true + * CharUtils.isAsciiPrintable('3') = true + * CharUtils.isAsciiPrintable('-') = true + * CharUtils.isAsciiPrintable('\n') = false + * CharUtils.isAsciiPrintable('©') = false + * </pre> + * + * @param ch the character to check + * @return true if between 32 and 126 inclusive + */ + public static boolean isAsciiPrintable(final char ch) { + return ch >= 32 && ch < 127; + } + + /** + * Checks whether the character is ASCII 7 bit control. + * + * <pre> + * CharUtils.isAsciiControl('a') = false + * CharUtils.isAsciiControl('A') = false + * CharUtils.isAsciiControl('3') = false + * CharUtils.isAsciiControl('-') = false + * CharUtils.isAsciiControl('\n') = true + * CharUtils.isAsciiControl('©') = false + * </pre> + * + * @param ch the character to check + * @return true if less than 32 or equals 127 + */ + public static boolean isAsciiControl(final char ch) { + return ch < 32 || ch == 127; + } + + /** + * Checks whether the character is ASCII 7 bit alphabetic. + * + * <pre> + * CharUtils.isAsciiAlpha('a') = true + * CharUtils.isAsciiAlpha('A') = true + * CharUtils.isAsciiAlpha('3') = false + * CharUtils.isAsciiAlpha('-') = false + * CharUtils.isAsciiAlpha('\n') = false + * CharUtils.isAsciiAlpha('©') = false + * </pre> + * + * @param ch the character to check + * @return true if between 65 and 90 or 97 and 122 inclusive + */ + public static boolean isAsciiAlpha(final char ch) { + return isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch); + } + + /** + * Checks whether the character is ASCII 7 bit alphabetic upper case. + * + * <pre> + * CharUtils.isAsciiAlphaUpper('a') = false + * CharUtils.isAsciiAlphaUpper('A') = true + * CharUtils.isAsciiAlphaUpper('3') = false + * CharUtils.isAsciiAlphaUpper('-') = false + * CharUtils.isAsciiAlphaUpper('\n') = false + * CharUtils.isAsciiAlphaUpper('©') = false + * </pre> + * + * @param ch the character to check + * @return true if between 65 and 90 inclusive + */ + public static boolean isAsciiAlphaUpper(final char ch) { + return ch >= 'A' && ch <= 'Z'; + } + + /** + * Checks whether the character is ASCII 7 bit alphabetic lower case. + * + * <pre> + * CharUtils.isAsciiAlphaLower('a') = true + * CharUtils.isAsciiAlphaLower('A') = false + * CharUtils.isAsciiAlphaLower('3') = false + * CharUtils.isAsciiAlphaLower('-') = false + * CharUtils.isAsciiAlphaLower('\n') = false + * CharUtils.isAsciiAlphaLower('©') = false + * </pre> + * + * @param ch the character to check + * @return true if between 97 and 122 inclusive + */ + public static boolean isAsciiAlphaLower(final char ch) { + return ch >= 'a' && ch <= 'z'; + } + + /** + * Checks whether the character is ASCII 7 bit numeric. + * + * <pre> + * CharUtils.isAsciiNumeric('a') = false + * CharUtils.isAsciiNumeric('A') = false + * CharUtils.isAsciiNumeric('3') = true + * CharUtils.isAsciiNumeric('-') = false + * CharUtils.isAsciiNumeric('\n') = false + * CharUtils.isAsciiNumeric('©') = false + * </pre> + * + * @param ch the character to check + * @return true if between 48 and 57 inclusive + */ + public static boolean isAsciiNumeric(final char ch) { + return ch >= '0' && ch <= '9'; + } + + /** + * Checks whether the character is ASCII 7 bit numeric. + * + * <pre> + * CharUtils.isAsciiAlphanumeric('a') = true + * CharUtils.isAsciiAlphanumeric('A') = true + * CharUtils.isAsciiAlphanumeric('3') = true + * CharUtils.isAsciiAlphanumeric('-') = false + * CharUtils.isAsciiAlphanumeric('\n') = false + * CharUtils.isAsciiAlphanumeric('©') = false + * </pre> + * + * @param ch the character to check + * @return true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive + */ + public static boolean isAsciiAlphanumeric(final char ch) { + return isAsciiAlpha(ch) || isAsciiNumeric(ch); + } + + /** + * Compares two {@code char} values numerically. This is the same functionality as provided in Java 7. + * + * @param x the first {@code char} to compare + * @param y the second {@code char} to compare + * @return the value {@code 0} if {@code x == y}; + * a value less than {@code 0} if {@code x < y}; and + * a value greater than {@code 0} if {@code x > y} + * @since 3.4 + */ + public static int compare(final char x, final char y) { + return x - y; + } +} |