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/*
 * 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;

/**
 * 

Operations on char primitives and Character objects.

* *

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.

* *

#ThreadSafe#

* @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 JLF: Escape Sequences * for Character and String Literals * @since 2.2 */ public static final char LF = '\n'; /** * Carriage return characterf CR ('\r', Unicode 000d). * * @see JLF: Escape Sequences * for Character and String Literals * @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 { for (char c = 0; c < CHAR_STRING_ARRAY.length; c++) { CHAR_STRING_ARRAY[c] = String.valueOf(c); } } /** *

{@code CharUtils} instances should NOT be constructed in standard programming. * Instead, the class should be used as {@code CharUtils.toString('c');}.

* *

This constructor is public to permit tools that require a JavaBean instance * to operate.

*/ public CharUtils() { } //----------------------------------------------------------------------- /** *

Converts the character to a Character.

* *

For ASCII 7 bit characters, this uses a cache that will return the * same Character object each time.

* *
     *   CharUtils.toCharacterObject(' ')  = ' '
     *   CharUtils.toCharacterObject('A')  = 'A'
     * 
* * @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.

* *

For ASCII 7 bit characters, this uses a cache that will return the * same Character object each time.

* *
     *   CharUtils.toCharacterObject(null) = null
     *   CharUtils.toCharacterObject("")   = null
     *   CharUtils.toCharacterObject("A")  = 'A'
     *   CharUtils.toCharacterObject("BA") = 'B'
     * 
* * @param str the character to convert * @return the Character value of the first letter of the String */ public static Character toCharacterObject(final String str) { if (StringUtils.isEmpty(str)) { return null; } return Character.valueOf(str.charAt(0)); } //----------------------------------------------------------------------- /** *

Converts the Character to a char throwing an exception for {@code null}.

* *
     *   CharUtils.toChar(' ')  = ' '
     *   CharUtils.toChar('A')  = 'A'
     *   CharUtils.toChar(null) throws IllegalArgumentException
     * 
* * @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) { Validate.notNull(ch, "ch"); return ch.charValue(); } /** *

Converts the Character to a char handling {@code null}.

* *
     *   CharUtils.toChar(null, 'X') = 'X'
     *   CharUtils.toChar(' ', 'X')  = ' '
     *   CharUtils.toChar('A', 'X')  = 'A'
     * 
* * @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) { if (ch == null) { return defaultValue; } return ch.charValue(); } //----------------------------------------------------------------------- /** *

Converts the String to a char using the first character, throwing * an exception on empty Strings.

* *
     *   CharUtils.toChar("A")  = 'A'
     *   CharUtils.toChar("BA") = 'B'
     *   CharUtils.toChar(null) throws IllegalArgumentException
     *   CharUtils.toChar("")   throws IllegalArgumentException
     * 
* * @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.

* *
     *   CharUtils.toChar(null, 'X') = 'X'
     *   CharUtils.toChar("", 'X')   = 'X'
     *   CharUtils.toChar("A", 'X')  = 'A'
     *   CharUtils.toChar("BA", 'X') = 'B'
     * 
* * @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) { if (StringUtils.isEmpty(str)) { return defaultValue; } return str.charAt(0); } //----------------------------------------------------------------------- /** *

Converts the character to the Integer it represents, throwing an * exception if the character is not numeric.

* *

This method converts the char '1' to the int 1 and so on.

* *
     *   CharUtils.toIntValue('3')  = 3
     *   CharUtils.toIntValue('A')  throws IllegalArgumentException
     * 
* * @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.

* *

This method converts the char '1' to the int 1 and so on.

* *
     *   CharUtils.toIntValue('3', -1)  = 3
     *   CharUtils.toIntValue('A', -1)  = -1
     * 
* * @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) { if (!isAsciiNumeric(ch)) { return defaultValue; } return ch - 48; } /** *

Converts the character to the Integer it represents, throwing an * exception if the character is not numeric.

* *

This method converts the char '1' to the int 1 and so on.

* *
     *   CharUtils.toIntValue('3')  = 3
     *   CharUtils.toIntValue(null) throws IllegalArgumentException
     *   CharUtils.toIntValue('A')  throws IllegalArgumentException
     * 
* * @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) { Validate.notNull(ch, "ch"); return toIntValue(ch.charValue()); } /** *

Converts the character to the Integer it represents, throwing an * exception if the character is not numeric.

* *

This method converts the char '1' to the int 1 and so on.

* *
     *   CharUtils.toIntValue(null, -1) = -1
     *   CharUtils.toIntValue('3', -1)  = 3
     *   CharUtils.toIntValue('A', -1)  = -1
     * 
* * @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) { if (ch == null) { return defaultValue; } return toIntValue(ch.charValue(), defaultValue); } //----------------------------------------------------------------------- /** *

Converts the character to a String that contains the one character.

* *

For ASCII 7 bit characters, this uses a cache that will return the * same String object each time.

* *
     *   CharUtils.toString(' ')  = " "
     *   CharUtils.toString('A')  = "A"
     * 
* * @param ch the character to convert * @return a String containing the one specified character */ public static String toString(final char ch) { if (ch < 128) { return CHAR_STRING_ARRAY[ch]; } return new String(new char[] {ch}); } /** *

Converts the character to a String that contains the one character.

* *

For ASCII 7 bit characters, this uses a cache that will return the * same String object each time.

* *

If {@code null} is passed in, {@code null} will be returned.

* *
     *   CharUtils.toString(null) = null
     *   CharUtils.toString(' ')  = " "
     *   CharUtils.toString('A')  = "A"
     * 
* * @param ch the character to convert * @return a String containing the one specified character */ public static String toString(final Character ch) { if (ch == null) { return null; } return toString(ch.charValue()); } //-------------------------------------------------------------------------- /** *

Converts the string to the Unicode format '\u0020'.

* *

This format is the Java source code format.

* *
     *   CharUtils.unicodeEscaped(' ') = "\u0020"
     *   CharUtils.unicodeEscaped('A') = "\u0041"
     * 
* * @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'.

* *

This format is the Java source code format.

* *

If {@code null} is passed in, {@code null} will be returned.

* *
     *   CharUtils.unicodeEscaped(null) = null
     *   CharUtils.unicodeEscaped(' ')  = "\u0020"
     *   CharUtils.unicodeEscaped('A')  = "\u0041"
     * 
* * @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) { if (ch == null) { return null; } return unicodeEscaped(ch.charValue()); } //-------------------------------------------------------------------------- /** *

Checks whether the character is ASCII 7 bit.

* *
     *   CharUtils.isAscii('a')  = true
     *   CharUtils.isAscii('A')  = true
     *   CharUtils.isAscii('3')  = true
     *   CharUtils.isAscii('-')  = true
     *   CharUtils.isAscii('\n') = true
     *   CharUtils.isAscii('©') = false
     * 
* * @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.

* *
     *   CharUtils.isAsciiPrintable('a')  = true
     *   CharUtils.isAsciiPrintable('A')  = true
     *   CharUtils.isAsciiPrintable('3')  = true
     *   CharUtils.isAsciiPrintable('-')  = true
     *   CharUtils.isAsciiPrintable('\n') = false
     *   CharUtils.isAsciiPrintable('©') = false
     * 
* * @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.

* *
     *   CharUtils.isAsciiControl('a')  = false
     *   CharUtils.isAsciiControl('A')  = false
     *   CharUtils.isAsciiControl('3')  = false
     *   CharUtils.isAsciiControl('-')  = false
     *   CharUtils.isAsciiControl('\n') = true
     *   CharUtils.isAsciiControl('©') = false
     * 
* * @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.

* *
     *   CharUtils.isAsciiAlpha('a')  = true
     *   CharUtils.isAsciiAlpha('A')  = true
     *   CharUtils.isAsciiAlpha('3')  = false
     *   CharUtils.isAsciiAlpha('-')  = false
     *   CharUtils.isAsciiAlpha('\n') = false
     *   CharUtils.isAsciiAlpha('©') = false
     * 
* * @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.

* *
     *   CharUtils.isAsciiAlphaUpper('a')  = false
     *   CharUtils.isAsciiAlphaUpper('A')  = true
     *   CharUtils.isAsciiAlphaUpper('3')  = false
     *   CharUtils.isAsciiAlphaUpper('-')  = false
     *   CharUtils.isAsciiAlphaUpper('\n') = false
     *   CharUtils.isAsciiAlphaUpper('©') = false
     * 
* * @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.

* *
     *   CharUtils.isAsciiAlphaLower('a')  = true
     *   CharUtils.isAsciiAlphaLower('A')  = false
     *   CharUtils.isAsciiAlphaLower('3')  = false
     *   CharUtils.isAsciiAlphaLower('-')  = false
     *   CharUtils.isAsciiAlphaLower('\n') = false
     *   CharUtils.isAsciiAlphaLower('©') = false
     * 
* * @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.

* *
     *   CharUtils.isAsciiNumeric('a')  = false
     *   CharUtils.isAsciiNumeric('A')  = false
     *   CharUtils.isAsciiNumeric('3')  = true
     *   CharUtils.isAsciiNumeric('-')  = false
     *   CharUtils.isAsciiNumeric('\n') = false
     *   CharUtils.isAsciiNumeric('©') = false
     * 
* * @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.

* *
     *   CharUtils.isAsciiAlphanumeric('a')  = true
     *   CharUtils.isAsciiAlphanumeric('A')  = true
     *   CharUtils.isAsciiAlphanumeric('3')  = true
     *   CharUtils.isAsciiAlphanumeric('-')  = false
     *   CharUtils.isAsciiAlphanumeric('\n') = false
     *   CharUtils.isAsciiAlphanumeric('©') = false
     * 
* * @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; } }




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