# Class StringUtils

java.lang.Object
org.apache.tomcat.util.buf.StringUtils

public final class StringUtils extends Object
Utility methods to build a separated list from a given set (not java.util.Set) of inputs and return that list as a string or append it to an existing StringBuilder. If the given set is null or empty, an empty string will be returned.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static void`
  `join(Iterable<String> iterable, char separator, StringBuilder sb)`
  Joins the elements of an iterable with the specified separator and appends the result to the given StringBuilder.
  `static <T> void`
  `join(Iterable<T> iterable, char separator, Function<T,String> function, StringBuilder sb)`
  Joins the elements of an iterable using the specified separator and function, and appends the result to the given StringBuilder.
  `static String`
  `join(String[] array)`
  Joins the elements of a string array with a comma separator.
  `static void`
  `join(String[] array, char separator, StringBuilder sb)`
  Joins the elements of a string array with the specified separator and appends the result to the given StringBuilder.
  `static String`
  `join(String a, String b)`
  Joins two strings with a comma separator.
  `static String`
  `join(Collection<String> collection)`
  Joins the elements of a collection with a comma separator.
  `static String`
  `join(Collection<String> collection, char separator)`
  Joins the elements of a collection with the specified separator.
  `static <T> void`
  `join(T[] array, char separator, Function<T,String> function, StringBuilder sb)`
  Joins the elements of an array using the specified separator and function, and appends the result to the given StringBuilder.
  `static String[]`
  `splitCommaSeparated(String s)`
  Splits a comma-separated string into an array of String values.

  ### Methods inherited from class Object

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

- ## Method Details

  - ### join

    public static String join(String a, String b)
    Joins two strings with a comma separator.
    Parameters:
      `a` - the first string
      `b` - the second string
    Returns:
      the joined string

  - ### join

    public static String join(String[] array)
    Joins the elements of a string array with a comma separator.
    Parameters:
      `array` - the array of strings to join
    Returns:
      the joined string

  - ### join

    public static void join(String[] array, char separator, StringBuilder sb)
    Joins the elements of a string array with the specified separator and appends the result to the given StringBuilder.
    Parameters:
      `array` - the array of strings to join
      `separator` - the separator character
      `sb` - the StringBuilder to append to

  - ### join

    public static String join(Collection<String> collection)
    Joins the elements of a collection with a comma separator.
    Parameters:
      `collection` - the collection of strings to join
    Returns:
      the joined string

  - ### join

    public static String join(Collection<String> collection, char separator)
    Joins the elements of a collection with the specified separator.
    Parameters:
      `collection` - the collection of strings to join
      `separator` - the separator character
    Returns:
      the joined string

  - ### join

    public static void join(Iterable<String> iterable, char separator, StringBuilder sb)
    Joins the elements of an iterable with the specified separator and appends the result to the given StringBuilder.
    Parameters:
      `iterable` - the iterable of strings to join
      `separator` - the separator character
      `sb` - the StringBuilder to append to

  - ### join

    public static <T> void join(T[] array, char separator, Function<T,String> function, StringBuilder sb)
    Joins the elements of an array using the specified separator and function, and appends the result to the given StringBuilder.
    Type Parameters:
      `T` - the element type
    Parameters:
      `array` - the array to join
      `separator` - the separator character
      `function` - the function to apply to each element
      `sb` - the StringBuilder to append to

  - ### join

    public static <T> void join(Iterable<T> iterable, char separator, Function<T,String> function, StringBuilder sb)
    Joins the elements of an iterable using the specified separator and function, and appends the result to the given StringBuilder.
    Type Parameters:
      `T` - the element type
    Parameters:
      `iterable` - the iterable to join
      `separator` - the separator character
      `function` - the function to apply to each element
      `sb` - the StringBuilder to append to

  - ### splitCommaSeparated

    public static String[] splitCommaSeparated(String s)
    Splits a comma-separated string into an array of String values. Whitespace around the commas is removed. Null or empty values will return a zero-element array.
    Parameters:
      `s` - The string to split by commas.
    Returns:
      An array of String values.