Package org.apache.commons.lang3

Class CharUtils

  • public class CharUtils
extends Object

    Operations on char primitives and Character objects.

    This class tries to handle null input gracefully. An exception will not be thrown for a null input. Each method documents its behavior in more detail.

    #ThreadSafe#

    Since:
    2.1

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static char CR
      Carriage return characterf CR ('\r', Unicode 000d).
      static char LF
      Linefeed character LF ('\n', Unicode 000a).
      static char NUL
      null control character ('\0'), abbreviated NUL.

    • Constructor Summary

      Constructors 
      Constructor Description
      CharUtils()
      CharUtils instances should NOT be constructed in standard programming.

    • Method Summary

      All Methods Static Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      static int compare​(char x, char y)
      Compares two char values numerically.
      static boolean isAscii​(char ch)
      Checks whether the character is ASCII 7 bit.
      static boolean isAsciiAlpha​(char ch)
      Checks whether the character is ASCII 7 bit alphabetic.
      static boolean isAsciiAlphaLower​(char ch)
      Checks whether the character is ASCII 7 bit alphabetic lower case.
      static boolean isAsciiAlphanumeric​(char ch)
      Checks whether the character is ASCII 7 bit numeric.
      static boolean isAsciiAlphaUpper​(char ch)
      Checks whether the character is ASCII 7 bit alphabetic upper case.
      static boolean isAsciiControl​(char ch)
      Checks whether the character is ASCII 7 bit control.
      static boolean isAsciiNumeric​(char ch)
      Checks whether the character is ASCII 7 bit numeric.
      static boolean isAsciiPrintable​(char ch)
      Checks whether the character is ASCII 7 bit printable.
      static char toChar​(Character ch)
      Converts the Character to a char throwing an exception for null.
      static char toChar​(Character ch, char defaultValue)
      Converts the Character to a char handling null.
      static char toChar​(String str)
      Converts the String to a char using the first character, throwing an exception on empty Strings.
      static char toChar​(String str, char defaultValue)
      Converts the String to a char using the first character, defaulting the value on empty Strings.
      static Character toCharacterObject​(char ch)
      Deprecated.
      Java 5 introduced Character.valueOf(char) which caches chars 0 through 127.
      static Character toCharacterObject​(String str)
      Converts the String to a Character using the first character, returning null for empty Strings.
      static int toIntValue​(char ch)
      Converts the character to the Integer it represents, throwing an exception if the character is not numeric.
      static int toIntValue​(char ch, int defaultValue)
      Converts the character to the Integer it represents, throwing an exception if the character is not numeric.
      static int toIntValue​(Character ch)
      Converts the character to the Integer it represents, throwing an exception if the character is not numeric.
      static int toIntValue​(Character ch, int defaultValue)
      Converts the character to the Integer it represents, throwing an exception if the character is not numeric.
      static String toString​(char ch)
      Converts the character to a String that contains the one character.
      static String toString​(Character ch)
      Converts the character to a String that contains the one character.
      static String unicodeEscaped​(char ch)
      Converts the string to the Unicode format ' '.
      static String unicodeEscaped​(Character ch)
      Converts the string to the Unicode format ' '.

    • Constructor Detail

      • CharUtils

        public CharUtils()

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

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

    • Method Detail

      • toCharacterObject

        @Deprecated
public static Character toCharacterObject​(char ch)
        Deprecated.
        Java 5 introduced Character.valueOf(char) which caches chars 0 through 127.

        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'
        Parameters:
        ch - the character to convert
        Returns:
        a Character of the specified character

      • toCharacterObject

        public static Character toCharacterObject​(String str)

        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'
        Parameters:
        str - the character to convert
        Returns:
        the Character value of the first letter of the String

      • toChar

        public static char toChar​(Character ch)

        Converts the Character to a char throwing an exception for null.

           CharUtils.toChar(' ')  = ' '
   CharUtils.toChar('A')  = 'A'
   CharUtils.toChar(null) throws IllegalArgumentException
        Parameters:
        ch - the character to convert
        Returns:
        the char value of the Character
        Throws:
        NullPointerException - if the Character is null

      • toChar

        public static char toChar​(Character ch,
                          char defaultValue)

        Converts the Character to a char handling null.

           CharUtils.toChar(null, 'X') = 'X'
   CharUtils.toChar(' ', 'X')  = ' '
   CharUtils.toChar('A', 'X')  = 'A'
        Parameters:
        ch - the character to convert
        defaultValue - the value to use if the Character is null
        Returns:
        the char value of the Character or the default if null

      • toChar

        public static char toChar​(String str)

        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
        Parameters:
        str - the character to convert
        Returns:
        the char value of the first letter of the String
        Throws:
        NullPointerException - if the string is null
        IllegalArgumentException - if the String is empty

      • toChar

        public static char toChar​(String str,
                          char defaultValue)

        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'
        Parameters:
        str - the character to convert
        defaultValue - the value to use if the Character is null
        Returns:
        the char value of the first letter of the String or the default if null

      • toIntValue

        public static int toIntValue​(char ch)

        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
        Parameters:
        ch - the character to convert
        Returns:
        the int value of the character
        Throws:
        IllegalArgumentException - if the character is not ASCII numeric

      • toIntValue

        public static int toIntValue​(char ch,
                             int defaultValue)

        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
        Parameters:
        ch - the character to convert
        defaultValue - the default value to use if the character is not numeric
        Returns:
        the int value of the character

      • toIntValue

        public static int toIntValue​(Character ch)

        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
        Parameters:
        ch - the character to convert, not null
        Returns:
        the int value of the character
        Throws:
        NullPointerException - if the Character is null
        IllegalArgumentException - if the Character is not ASCII numeric

      • toIntValue

        public static int toIntValue​(Character ch,
                             int defaultValue)

        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
        Parameters:
        ch - the character to convert
        defaultValue - the default value to use if the character is not numeric
        Returns:
        the int value of the character

      • toString

        public static String toString​(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.

           CharUtils.toString(' ')  = " "
   CharUtils.toString('A')  = "A"
        Parameters:
        ch - the character to convert
        Returns:
        a String containing the one specified character

      • toString

        public static String toString​(Character 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 null is passed in, null will be returned.

           CharUtils.toString(null) = null
   CharUtils.toString(' ')  = " "
   CharUtils.toString('A')  = "A"
        Parameters:
        ch - the character to convert
        Returns:
        a String containing the one specified character

      • unicodeEscaped

        public static String unicodeEscaped​(char ch)

        Converts the string to the Unicode format ' '.

        This format is the Java source code format.

           CharUtils.unicodeEscaped(' ') = " "
   CharUtils.unicodeEscaped('A') = "A"
        Parameters:
        ch - the character to convert
        Returns:
        the escaped Unicode string

      • unicodeEscaped

        public static String unicodeEscaped​(Character ch)

        Converts the string to the Unicode format ' '.

        This format is the Java source code format.

        If null is passed in, null will be returned.

           CharUtils.unicodeEscaped(null) = null
   CharUtils.unicodeEscaped(' ')  = " "
   CharUtils.unicodeEscaped('A')  = "A"
        Parameters:
        ch - the character to convert, may be null
        Returns:
        the escaped Unicode string, null if null input

      • isAscii

        public static boolean isAscii​(char ch)

        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
        Parameters:
        ch - the character to check
        Returns:
        true if less than 128

      • isAsciiPrintable

        public static boolean isAsciiPrintable​(char ch)

        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
        Parameters:
        ch - the character to check
        Returns:
        true if between 32 and 126 inclusive

      • isAsciiControl

        public static boolean isAsciiControl​(char ch)

        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
        Parameters:
        ch - the character to check
        Returns:
        true if less than 32 or equals 127

      • isAsciiAlpha

        public static boolean isAsciiAlpha​(char ch)

        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
        Parameters:
        ch - the character to check
        Returns:
        true if between 65 and 90 or 97 and 122 inclusive

      • isAsciiAlphaUpper

        public static boolean isAsciiAlphaUpper​(char 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
        Parameters:
        ch - the character to check
        Returns:
        true if between 65 and 90 inclusive

      • isAsciiAlphaLower

        public static boolean isAsciiAlphaLower​(char ch)

        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
        Parameters:
        ch - the character to check
        Returns:
        true if between 97 and 122 inclusive

      • isAsciiNumeric

        public static boolean isAsciiNumeric​(char ch)

        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
        Parameters:
        ch - the character to check
        Returns:
        true if between 48 and 57 inclusive

      • isAsciiAlphanumeric

        public static boolean isAsciiAlphanumeric​(char ch)

        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
        Parameters:
        ch - the character to check
        Returns:
        true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive

      • compare

        public static int compare​(char x,
                          char y)

        Compares two char values numerically. This is the same functionality as provided in Java 7.

        Parameters:
        x - the first char to compare
        y - the second char to compare
        Returns:
        the value 0 if x == y; a value less than 0 if x < y; and a value greater than 0 if x > y
        Since:
        3.4