Class StringUtils

java.lang.Object
org.parboiled.common.StringUtils
public final class StringUtils extends Object
General utility methods for string manipulation.

  • Method Summary

    Modifier and Type
    Method
    Description
    static boolean
    equalsIgnoreCase(String str1, String str2)
    Compares two Strings, returning true if they are equal ignoring the case.
    static String
    escape(char c)
    Replaces carriage returns, newlines, tabs, formfeeds and the special chars defined in Characters with their respective escape sequences.
    static String
    escape(String string)
    Replaces carriage returns, newlines, tabs, formfeeds and the special chars defined in Characters with their respective escape sequences.
    static boolean
    isEmpty(String str)
    Checks if a String is empty ("") or null.
    static boolean
    isNotEmpty(String str)
    Checks if a String is not empty ("") and not null.
    static String
    join(Iterable iterable, String separator)
    Joins the elements of the provided Iterable into a single String containing the provided elements.
    static String
    join(Object[] array, String separator)
    Joins the elements of the provided array into a single String containing the provided list of elements.
    static String
    join(Object[] array, String separator, int startIndex, int endIndex)
    Joins the elements of the provided array into a single String containing the provided list of elements.
    static String
    join(Iterator iterator, String separator)
    Joins the elements of the provided Iterator into a single String containing the provided elements.
    static String
    left(String str, int len)
    Gets the leftmost len characters of a String.
    static int
    length(String str)
    Gets a String's length or 0 if the String is null.
    static String
    mid(String str, int pos, int len)
    Gets len characters from the middle of a String.
    static String
    repeat(char c, int n)
    Creates a string consisting of n times the given character.
    static String
    right(String str, int len)
    Gets the rightmost len characters of a String.
    static boolean
    startsWith(String string, String prefix)
    Test whether a string starts with a given prefix, handling null values without exceptions.
    static String
    substring(String str, int start)
    Gets a substring from the specified String avoiding exceptions.
    static String
    substring(String str, int start, int end)
    Gets a substring from the specified String avoiding exceptions.

    Methods inherited from class Object

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

  • Method Details

    • escape

      public static String escape(String string)
      Replaces carriage returns, newlines, tabs, formfeeds and the special chars defined in Characters with their respective escape sequences.
      Parameters:
      string - the string
      Returns:
      the escaped string

    • escape

      public static String escape(char c)
      Replaces carriage returns, newlines, tabs, formfeeds and the special chars defined in Characters with their respective escape sequences.
      Parameters:
      c - the character to escape
      Returns:
      the escaped string

    • repeat

      public static String repeat(char c, int n)
      Creates a string consisting of n times the given character.
      Parameters:
      c - the char
      n - the number of times to repeat
      Returns:
      the string

    • join

      public static String join(Iterable iterable, String separator)

      Joins the elements of the provided Iterable into a single String containing the provided elements.

      No delimiter is added before or after the list. A null separator is the same as an empty String ("").

      Parameters:
      iterable - the Iterable of values to join together, may be null
      separator - the separator character to use, null treated as ""
      Returns:
      the joined String, null if null iterator input

    • join

      public static String join(Iterator iterator, String separator)

      Joins the elements of the provided Iterator into a single String containing the provided elements.

      No delimiter is added before or after the list. A null separator is the same as an empty String ("").

      Parameters:
      iterator - the Iterator of values to join together, may be null
      separator - the separator character to use, null treated as ""
      Returns:
      the joined String, null if null iterator input

    • join

      public static String join(Object[] array, String separator)

      Joins the elements of the provided array into a single String containing the provided list of elements.

      No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

      StringUtils.join(null, *)                = null
StringUtils.join([], *)                  = ""
StringUtils.join([null], *)              = ""
StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
StringUtils.join(["a", "b", "c"], null)  = "abc"
StringUtils.join(["a", "b", "c"], "")    = "abc"
StringUtils.join([null, "", "a"], ',')   = ",,a"
      Parameters:
      array - the array of values to join together, may be null
      separator - the separator character to use, null treated as ""
      Returns:
      the joined String, null if null array input

    • join

      public static String join(Object[] array, String separator, int startIndex, int endIndex)

      Joins the elements of the provided array into a single String containing the provided list of elements.

      No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

      StringUtils.join(null, *)                = null
StringUtils.join([], *)                  = ""
StringUtils.join([null], *)              = ""
StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
StringUtils.join(["a", "b", "c"], null)  = "abc"
StringUtils.join(["a", "b", "c"], "")    = "abc"
StringUtils.join([null, "", "a"], ',')   = ",,a"
      Parameters:
      array - the array of values to join together, may be null
      separator - the separator character to use, null treated as ""
      startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array
      endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
      Returns:
      the joined String, null if null array input

    • isEmpty

      public static boolean isEmpty(String str)

      Checks if a String is empty ("") or null.

      StringUtils.isEmpty(null)      = true
StringUtils.isEmpty("")        = true
StringUtils.isEmpty(" ")       = false
StringUtils.isEmpty("bob")     = false
StringUtils.isEmpty("  bob  ") = false
      Parameters:
      str - the String to check, may be null
      Returns:
      true if the String is empty or null

    • isNotEmpty

      public static boolean isNotEmpty(String str)

      Checks if a String is not empty ("") and not null.

      StringUtils.isNotEmpty(null)      = false
StringUtils.isNotEmpty("")        = false
StringUtils.isNotEmpty(" ")       = true
StringUtils.isNotEmpty("bob")     = true
StringUtils.isNotEmpty("  bob  ") = true
      Parameters:
      str - the String to check, may be null
      Returns:
      true if the String is not empty and not null

    • length

      public static int length(String str)
      Gets a String's length or 0 if the String is null.
      Parameters:
      str - a String or null
      Returns:
      String length or 0 if the String is null.

    • equalsIgnoreCase

      public static boolean equalsIgnoreCase(String str1, String str2)

      Compares two Strings, returning true if they are equal ignoring the case.

      nulls are handled without exceptions. Two null references are considered equal. Comparison is case insensitive.

      StringUtils.equalsIgnoreCase(null, null)   = true
StringUtils.equalsIgnoreCase(null, "abc")  = false
StringUtils.equalsIgnoreCase("abc", null)  = false
StringUtils.equalsIgnoreCase("abc", "abc") = true
StringUtils.equalsIgnoreCase("abc", "ABC") = true
      Parameters:
      str1 - the first String, may be null
      str2 - the second String, may be null
      Returns:
      true if the Strings are equal, case insensitive, or both null

    • startsWith

      public static boolean startsWith(String string, String prefix)
      Test whether a string starts with a given prefix, handling null values without exceptions. StringUtils.startsWith(null, null) = false StringUtils.startsWith(null, "abc") = false StringUtils.startsWith("abc", null) = true StringUtils.startsWith("abc", "ab") = true StringUtils.startsWith("abc", "abc") = true
      Parameters:
      string - the string
      prefix - the prefix
      Returns:
      true if string starts with prefix

    • substring

      public static String substring(String str, int start)

      Gets a substring from the specified String avoiding exceptions.

      A negative start position can be used to start n characters from the end of the String.

      A null String will return null. An empty ("") String will return "".

      StringUtils.substring(null, *)   = null
StringUtils.substring("", *)     = ""
StringUtils.substring("abc", 0)  = "abc"
StringUtils.substring("abc", 2)  = "c"
StringUtils.substring("abc", 4)  = ""
StringUtils.substring("abc", -2) = "bc"
StringUtils.substring("abc", -4) = "abc"
      Parameters:
      str - the String to get the substring from, may be null
      start - the position to start from, negative means count back from the end of the String by this many characters
      Returns:
      substring from start position, null if null String input

    • substring

      public static String substring(String str, int start, int end)

      Gets a substring from the specified String avoiding exceptions.

      A negative start position can be used to start/end n characters from the end of the String.

      The returned substring starts with the character in the start position and ends before the end position. All position counting is zero-based -- i.e., to start at the beginning of the string use start = 0. Negative start and end positions can be used to specify offsets relative to the end of the String.

      If start is not strictly to the left of end, "" is returned.

      StringUtils.substring(null, *, *)    = null
StringUtils.substring("", * ,  *)    = "";
StringUtils.substring("abc", 0, 2)   = "ab"
StringUtils.substring("abc", 2, 0)   = ""
StringUtils.substring("abc", 2, 4)   = "c"
StringUtils.substring("abc", 4, 6)   = ""
StringUtils.substring("abc", 2, 2)   = ""
StringUtils.substring("abc", -2, -1) = "b"
StringUtils.substring("abc", -4, 2)  = "ab"
      Parameters:
      str - the String to get the substring from, may be null
      start - the position to start from, negative means count back from the end of the String by this many characters
      end - the position to end at (exclusive), negative means count back from the end of the String by this many characters
      Returns:
      substring from start position to end positon, null if null String input

    • left

      public static String left(String str, int len)

      Gets the leftmost len characters of a String.

      If len characters are not available, or the String is null, the String will be returned without an exception. An exception is thrown if len is negative.

      StringUtils.left(null, *)    = null
StringUtils.left(*, -ve)     = ""
StringUtils.left("", *)      = ""
StringUtils.left("abc", 0)   = ""
StringUtils.left("abc", 2)   = "ab"
StringUtils.left("abc", 4)   = "abc"
      Parameters:
      str - the String to get the leftmost characters from, may be null
      len - the length of the required String, must be zero or positive
      Returns:
      the leftmost characters, null if null String input

    • right

      public static String right(String str, int len)

      Gets the rightmost len characters of a String.

      If len characters are not available, or the String is null, the String will be returned without an an exception. An exception is thrown if len is negative.

      StringUtils.right(null, *)    = null
StringUtils.right(*, -ve)     = ""
StringUtils.right("", *)      = ""
StringUtils.right("abc", 0)   = ""
StringUtils.right("abc", 2)   = "bc"
StringUtils.right("abc", 4)   = "abc"
      Parameters:
      str - the String to get the rightmost characters from, may be null
      len - the length of the required String, must be zero or positive
      Returns:
      the rightmost characters, null if null String input

    • mid

      public static String mid(String str, int pos, int len)

      Gets len characters from the middle of a String.

      If len characters are not available, the remainder of the String will be returned without an exception. If the String is null, null will be returned. An exception is thrown if len is negative.

      StringUtils.mid(null, *, *)    = null
StringUtils.mid(*, *, -ve)     = ""
StringUtils.mid("", 0, *)      = ""
StringUtils.mid("abc", 0, 2)   = "ab"
StringUtils.mid("abc", 0, 4)   = "abc"
StringUtils.mid("abc", 2, 4)   = "c"
StringUtils.mid("abc", 4, 2)   = ""
StringUtils.mid("abc", -2, 2)  = "ab"
      Parameters:
      str - the String to get the characters from, may be null
      pos - the position to start from, negative treated as zero
      len - the length of the required String, must be zero or positive
      Returns:
      the middle characters, null if null String input