* 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; } }