Package org.apache.taglibs.standard.functions

Class Functions

java.lang.Object
org.apache.taglibs.standard.functions.Functions
public class Functions extends Object
Static functions that extend the Expression Language with standardized behaviour commonly used by page authors.

Implementation Note: When passing a String parameter, section 1.18.2 of the EL specification requires the container to coerce a null value to an empty string. These implementation assume such behaviour and do not check for null parameters. Passing a null will generally trigger a NullPointerException.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Functions()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static boolean
    contains(String input, String substring)
    Tests if a string contains the specified substring.
    static boolean
    containsIgnoreCase(String input, String substring)
    Tests if a string contains the specified substring in a case insensitive way.
    static boolean
    endsWith(String input, String suffix)
    Tests if a string ends with the specified suffix according to the semantics of String#endsWith().
    static String
    escapeXml(String input)
    Escapes characters that could be interpreted as XML markup as defined by the <c:out> action.
    static int
    indexOf(String input, String substring)
    Returns the index (0-based) withing a string of the first occurrence of a specified substring according to the semantics of the method String#indexOf().
    static String
    join(String[] array, String separator)
    Joins all elements of an array into a string.
    static int
    length(Object obj)
    Returns the number of items in a collection or the number of characters in a string.
    static String
    replace(String input, String before, String after)
    Returns a string resulting from replacing all occurrences of a "before" substring with an "after" substring.
    static String[]
    split(String input, String delimiters)
    Splits a string into an array of substrings according to the semantics of StringTokenizer.
    static boolean
    startsWith(String input, String prefix)
    Tests if a string starts with the specified prefix according to the semantics of String#startsWith().
    static String
    substring(String input, int beginIndex, int endIndex)
    Returns a subset of a string according to the semantics of String#substring() with additional semantics as follows: if beginIndex invalid input: '<' 0 its value is adjusted to 0 if endIndex invalid input: '<' 0 or greater than the string length, its value is adjusted to the length of the string if endIndex invalid input: '<' beginIndex, an empty string is returned
    static String
    substringAfter(String input, String substring)
    Returns a subset of a string following the first occurrence of a specific substring.
    static String
    substringBefore(String input, String substring)
    Returns a subset of a string immediately before the first occurrence of a specific substring.
    static String
    toLowerCase(String input)
    Converts all of the characters of the input string to lower case according to the semantics of method String#toLowerCase().
    static String
    toUpperCase(String input)
    Converts all of the characters of the input string to upper case according to the semantics of method String#toUpperCase().
    static String
    trim(String input)
    removes whitespace from both ends of a string according to the semantics of String#trim().

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Functions

      public Functions()

  • Method Details

    • toUpperCase

      public static String toUpperCase(String input)
      Converts all of the characters of the input string to upper case according to the semantics of method String#toUpperCase().
      Parameters:
      input - the input string on which the transformation to upper case is applied
      Returns:
      the input string transformed to upper case

    • toLowerCase

      public static String toLowerCase(String input)
      Converts all of the characters of the input string to lower case according to the semantics of method String#toLowerCase().
      Parameters:
      input - the input string on which the transformation to lower case is applied
      Returns:
      the input string transformed to lower case

    • indexOf

      public static int indexOf(String input, String substring)
      Returns the index (0-based) withing a string of the first occurrence of a specified substring according to the semantics of the method String#indexOf().

      If substring is empty, this matches the beginning of the string and the value returned is 0.

      Parameters:
      input - the input string on which the function is applied
      substring - the substring to search for in the input string
      Returns:
      the 0-based index of the first matching substring, or -1 if it does not occur

    • contains

      public static boolean contains(String input, String substring)
      Tests if a string contains the specified substring.
      Parameters:
      input - the input string on which the function is applied
      substring - the substring tested for
      Returns:
      true if the character sequence represented by the substring exists in the string

    • containsIgnoreCase

      public static boolean containsIgnoreCase(String input, String substring)
      Tests if a string contains the specified substring in a case insensitive way. Equivalent to fn:contains(fn:toUpperCase(string), fn:toUpperCase(substring)).
      Parameters:
      input - the input string on which the function is applied
      substring - the substring tested for
      Returns:
      true if the character sequence represented by the substring exists in the string

    • startsWith

      public static boolean startsWith(String input, String prefix)
      Tests if a string starts with the specified prefix according to the semantics of String#startsWith().
      Parameters:
      input - the input string on which the function is applied
      prefix - the prefix to be matched
      Returns:
      true if the input string starts with the prefix

    • endsWith

      public static boolean endsWith(String input, String suffix)
      Tests if a string ends with the specified suffix according to the semantics of String#endsWith().
      Parameters:
      input - the input string on which the function is applied
      suffix - the suffix to be matched
      Returns:
      true if the input string ends with the suffix

    • substring

      public static String substring(String input, int beginIndex, int endIndex)
      Returns a subset of a string according to the semantics of String#substring() with additional semantics as follows:
      • if beginIndex invalid input: '<' 0 its value is adjusted to 0
      • if endIndex invalid input: '<' 0 or greater than the string length, its value is adjusted to the length of the string
      • if endIndex invalid input: '<' beginIndex, an empty string is returned
      Parameters:
      input - the input string on which the substring function is applied
      beginIndex - the beginning index (0-based), inclusive
      endIndex - the end index (0-based), exclusive
      Returns:
      a subset of string

    • substringAfter

      public static String substringAfter(String input, String substring)
      Returns a subset of a string following the first occurrence of a specific substring.

      If the substring is empty, it matches the beginning of the input string and the entire input string is returned. If the substring does not occur, an empty string is returned.

      Parameters:
      input - the input string on which the substring function is applied
      substring - the substring that delimits the beginning of the subset of the input string to be returned
      Returns:
      a substring of the input string that starts at the first character after the specified substring

    • substringBefore

      public static String substringBefore(String input, String substring)
      Returns a subset of a string immediately before the first occurrence of a specific substring.

      If the substring is empty, it matches the beginning of the input string and an empty string is returned. If the substring does not occur, an empty string is returned.

      Parameters:
      input - the input string on which the substring function is applied
      substring - the substring that delimits the beginning of the subset of the input string to be returned
      Returns:
      a substring of the input string that starts at the first character after the specified substring

    • escapeXml

      public static String escapeXml(String input)
      Escapes characters that could be interpreted as XML markup as defined by the <c:out> action.
      Parameters:
      input - the string to escape
      Returns:
      escaped string

    • trim

      public static String trim(String input)
      removes whitespace from both ends of a string according to the semantics of String#trim().
      Parameters:
      input - the input string to be trimmed
      Returns:
      the trimmed string

    • replace

      public static String replace(String input, String before, String after)
      Returns a string resulting from replacing all occurrences of a "before" substring with an "after" substring. The string is processed once and not reprocessed for further replacements.
      Parameters:
      input - the string on which the replacement is to be applied
      before - the substring to replace
      after - the replacement substring
      Returns:
      a string with before replaced with after

    • split

      public static String[] split(String input, String delimiters)
      Splits a string into an array of substrings according to the semantics of StringTokenizer. If the input string is empty, a single element array containing an empty string is returned. If the delimiters are empty, a single element array containing the input string is returned.
      Parameters:
      input - the string to split
      delimiters - characters used to split the string
      Returns:
      an array of strings

    • join

      public static String join(String[] array, String separator)
      Joins all elements of an array into a string.

      Implementation Note: The specification does not define what happens when elements in the array are null. For compatibility with previous implementations, the string "null" is used although EL conventions would suggest an empty string might be better.

      Parameters:
      array - an array of strings to be joined
      separator - used to separate the joined strings
      Returns:
      all array elements joined into one string with the specified separator

    • length

      public static int length(Object obj) throws JspTagException
      Returns the number of items in a collection or the number of characters in a string. The collection can be of any type supported for the items attribute of the <c:forEach> action.
      Parameters:
      obj - the collection or string whose length should be computed
      Returns:
      the length of the collection or string; 0 if obj is null
      Throws:
      JspTagException - if the type is not valid