org.apache.commons.lang3

## Class CharSetUtils

- java.lang.Object
- - org.apache.commons.lang3.CharSetUtils

-     public class CharSetUtils
      extends Object

  Operations on `CharSet` instances.

  This class handles `null` input gracefully. An exception will not be thrown for a `null` input. Each method documents its behaviour in more detail.

  #ThreadSafe#

  Since:
    1.0
  See Also:
    `CharSet`

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `CharSetUtils()` CharSetUtils instances should NOT be constructed in standard programming.

  - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static boolean` | `containsAny(String str, String... set)` Takes an argument in set-syntax, see evaluateSet, and identifies whether any of the characters are present in the specified string.
    `static int` | `count(String str, String... set)` Takes an argument in set-syntax, see evaluateSet, and returns the number of characters present in the specified string.
    `static String` | `delete(String str, String... set)` Takes an argument in set-syntax, see evaluateSet, and deletes any of characters present in the specified string.
    `static String` | `keep(String str, String... set)` Takes an argument in set-syntax, see evaluateSet, and keeps any of characters present in the specified string.
    `static String` | `squeeze(String str, String... set)` Squeezes any repetitions of a character that is mentioned in the supplied set.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### CharSetUtils

          public CharSetUtils()

      CharSetUtils instances should NOT be constructed in standard programming. Instead, the class should be used as `CharSetUtils.evaluateSet(null);`.

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

  - ### Method Detail

    - #### squeeze

          public static String squeeze(String str,
                                       String... set)

      Squeezes any repetitions of a character that is mentioned in the supplied set.

           CharSetUtils.squeeze(null, *)        = null
           CharSetUtils.squeeze("", *)          = ""
           CharSetUtils.squeeze(*, null)        = *
           CharSetUtils.squeeze(*, "")          = *
           CharSetUtils.squeeze("hello", "k-p") = "helo"
           CharSetUtils.squeeze("hello", "a-e") = "hello"

      Parameters:
        `str` - the string to squeeze, may be null
        `set` - the character set to use for manipulation, may be null
      Returns:
        the modified String, `null` if null string input
      See Also:
        `for set-syntax.`

    - #### containsAny

          public static boolean containsAny(String str,
                                            String... set)

      Takes an argument in set-syntax, see evaluateSet, and identifies whether any of the characters are present in the specified string.

           CharSetUtils.containsAny(null, *)        = false
           CharSetUtils.containsAny("", *)          = false
           CharSetUtils.containsAny(*, null)        = false
           CharSetUtils.containsAny(*, "")          = false
           CharSetUtils.containsAny("hello", "k-p") = true
           CharSetUtils.containsAny("hello", "a-d") = false

      Parameters:
        `str` - String to look for characters in, may be null
        `set` - String[] set of characters to identify, may be null
      Returns:
        whether or not the characters in the set are in the primary string
      Since:
        3.2
      See Also:
        `for set-syntax.`

    - #### count

          public static int count(String str,
                                  String... set)

      Takes an argument in set-syntax, see evaluateSet, and returns the number of characters present in the specified string.

           CharSetUtils.count(null, *)        = 0
           CharSetUtils.count("", *)          = 0
           CharSetUtils.count(*, null)        = 0
           CharSetUtils.count(*, "")          = 0
           CharSetUtils.count("hello", "k-p") = 3
           CharSetUtils.count("hello", "a-e") = 1

      Parameters:
        `str` - String to count characters in, may be null
        `set` - String[] set of characters to count, may be null
      Returns:
        the character count, zero if null string input
      See Also:
        `for set-syntax.`

    - #### keep

          public static String keep(String str,
                                    String... set)

      Takes an argument in set-syntax, see evaluateSet, and keeps any of characters present in the specified string.

           CharSetUtils.keep(null, *)        = null
           CharSetUtils.keep("", *)          = ""
           CharSetUtils.keep(*, null)        = ""
           CharSetUtils.keep(*, "")          = ""
           CharSetUtils.keep("hello", "hl")  = "hll"
           CharSetUtils.keep("hello", "le")  = "ell"

      Parameters:
        `str` - String to keep characters from, may be null
        `set` - String[] set of characters to keep, may be null
      Returns:
        the modified String, `null` if null string input
      Since:
        2.0
      See Also:
        `for set-syntax.`

    - #### delete

          public static String delete(String str,
                                      String... set)

      Takes an argument in set-syntax, see evaluateSet, and deletes any of characters present in the specified string.

           CharSetUtils.delete(null, *)        = null
           CharSetUtils.delete("", *)          = ""
           CharSetUtils.delete(*, null)        = *
           CharSetUtils.delete(*, "")          = *
           CharSetUtils.delete("hello", "hl")  = "eo"
           CharSetUtils.delete("hello", "le")  = "ho"

      Parameters:
        `str` - String to delete characters from, may be null
        `set` - String[] set of characters to delete, may be null
      Returns:
        the modified String, `null` if null string input
      See Also:
        `for set-syntax.`

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