org.jooq.tools

Class StringUtils

java.lang.Object

org.jooq.tools.StringUtils

public final class StringUtils
extends java.lang.Object

Operations on String that are null safe.

• IsEmpty/IsBlank - checks if a String contains text
• Trim/Strip - removes leading and trailing whitespace
• Equals - compares two strings null-safe
• startsWith - check if a String starts with a prefix null-safe
• endsWith - check if a String ends with a suffix null-safe
• IndexOf/LastIndexOf/Contains - null-safe index-of checks
• IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
• ContainsOnly/ContainsNone/ContainsAny - does String contains only/none/any of these characters
• Substring/Left/Right/Mid - null-safe substring extractions
• SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings
• Split/Join - splits a String into an array of substrings and vice versa
• Remove/Delete - removes part of a String
• Replace/Overlay - Searches a String and replaces one String with another
• Chomp/Chop - removes the last part of a String
• LeftPad/RightPad/Center/Repeat - pads a String
• UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String
• CountMatches - counts the number of occurrences of one String in another
• IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
• DefaultString - protects against a null input String
• Reverse/ReverseDelimited - reverses a String
• Abbreviate - abbreviates a string using ellipsis
• Difference - compares Strings and reports on their differences
• LevensteinDistance - the number of changes needed to change one String into another

The StringUtils class defines certain words related to String handling.

• null - null
• empty - a zero-length string ("")
• space - the space character (' ', char 32)
• whitespace - the characters defined by Character.isWhitespace(char)
• trim - the characters <= 32 as in String.trim()

StringUtils handles null input Strings quietly. That is to say that a null input will return null. Where a boolean or int is being returned details vary by method.

A side effect of the null handling is that a NullPointerException should be considered a bug in StringUtils (except for deprecated methods).

Methods in this class give sample code to explain their operation. The symbol * is used to indicate any input including null.

Since:

1.0

Version:

$Id: StringUtils.java 911986 2010-02-19 21:19:05Z niallp $

Author:

Apache Software Foundation, Apache Jakarta Turbine, Jon S. Stevens, Daniel L. Rall, Greg Coladonato, Ed Korthof, Rand McNeely, Fredrik Westermarck, Holger Krauth, Alexander Day Chaffee, Henning P. Schmiedehausen, Arun Mammen Thomas, Gary Gregory, Phil Steitz, Al Chou, Michael Davey, Reuben Sivan, Chris Hyzer, Scott Johnson

See Also:

String

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	EMPTY The empty String "".
static int	INDEX_NOT_FOUND Represents a failed index search.

Method Summary

Modifier and Type	Method and Description
static java.lang.String	abbreviate(java.lang.String str, int maxWidth) Abbreviates a String using ellipses.
static java.lang.String	abbreviate(java.lang.String str, int offset, int maxWidth) Abbreviates a String using ellipses.
static boolean	containsAny(java.lang.String str, char... searchChars) Checks if the String contains any character in the given set of characters.
static int	countMatches(java.lang.String str, java.lang.String sub) Counts how many times the substring appears in the larger String.
static java.lang.String	defaultIfBlank(java.lang.String str, java.lang.String defaultStr) Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or null, the value of defaultStr.
static java.lang.String	defaultIfEmpty(java.lang.String str, java.lang.String defaultStr) Returns either the passed in String, or if the String is empty or null, the value of defaultStr.
static <T> T	defaultIfNull(T object, T defaultValue) Returns a default value if the object passed is null.
static java.lang.String	defaultString(java.lang.String str) Returns either the passed in String, or if the String is null, an empty String ("").
static java.lang.String	defaultString(java.lang.String str, java.lang.String defaultStr) Returns either the passed in String, or if the String is null, the value of defaultStr.
static boolean	equals(java.lang.Object object1, java.lang.Object object2) Compares two objects for equality, where either one or both objects may be null.
static boolean	isBlank(java.lang.String str) Checks if a String is whitespace, empty ("") or null.
static boolean	isEmpty(java.lang.String str) Checks if a String is empty ("") or null.
static java.lang.String	join(java.lang.Object[] array, char separator) Joins the elements of the provided array into a single String containing the provided list of elements.
static java.lang.String	join(java.lang.Object[] array, char separator, int startIndex, int endIndex) Joins the elements of the provided array into a single String containing the provided list of elements.
static java.lang.String	join(java.lang.Object[] array, java.lang.String separator) Joins the elements of the provided array into a single String containing the provided list of elements.
static java.lang.String	join(java.lang.Object[] array, java.lang.String separator, int startIndex, int endIndex) Joins the elements of the provided array into a single String containing the provided list of elements.
static <T> java.lang.String	join(T... elements) Joins the elements of the provided array into a single String containing the provided list of elements.
static java.lang.String	leftPad(java.lang.String str, int size) Left pad a String with spaces (' ').
static java.lang.String	leftPad(java.lang.String str, int size, char padChar) Left pad a String with a specified character.
static java.lang.String	leftPad(java.lang.String str, int size, java.lang.String padStr) Left pad a String with a specified String.
static java.lang.String	replace(java.lang.String text, java.lang.String searchString, java.lang.String replacement) Replaces all occurrences of a String within another String.
static java.lang.String	replace(java.lang.String text, java.lang.String searchString, java.lang.String replacement, int max) Replaces a String with another String inside a larger String, for the first max values of the search String.
static java.lang.String	replaceEach(java.lang.String text, java.lang.String[] searchList, java.lang.String[] replacementList) Replaces all occurrences of Strings within another String.
static java.lang.String	rightPad(java.lang.String str, int size) Right pad a String with spaces (' ').
static java.lang.String	rightPad(java.lang.String str, int size, char padChar) Right pad a String with a specified character.
static java.lang.String	rightPad(java.lang.String str, int size, java.lang.String padStr) Right pad a String with a specified String.
static java.lang.String[]	split(java.lang.String regex, java.lang.CharSequence input) A custom adaptation of Pattern.split(CharSequence, int).
static java.lang.String	toCamelCase(java.lang.String string) Convert a string to camel case
static java.lang.String	toCamelCaseLC(java.lang.String string) Convert a string to camel case starting with a lower case letter
static java.lang.String	toLC(java.lang.String string) Change a string's first letter to lower case

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final java.lang.String EMPTY

The empty String "".

Since:

2.0

See Also:

Constant Field Values

INDEX_NOT_FOUND

public static final int INDEX_NOT_FOUND

Represents a failed index search.

Since:

2.1

See Also:

Constant Field Values

Method Detail

defaultString

public static java.lang.String defaultString(java.lang.String str)

Returns either the passed in String, or if the String is null, an empty String ("").

 StringUtils.defaultString(null)  = ""
 StringUtils.defaultString("")    = ""
 StringUtils.defaultString("bat") = "bat"
 

Parameters:

str - the String to check, may be null

Returns:

the passed in String, or the empty String if it was null

See Also:

String.valueOf(Object)

defaultString

public static java.lang.String defaultString(java.lang.String str,
                                             java.lang.String defaultStr)

Returns either the passed in String, or if the String is null, the value of defaultStr.

 StringUtils.defaultString(null, "NULL")  = "NULL"
 StringUtils.defaultString("", "NULL")    = ""
 StringUtils.defaultString("bat", "NULL") = "bat"
 

Parameters:

str - the String to check, may be null

defaultStr - the default String to return if the input is null, may be null

Returns:

the passed in String, or the default if it was null

See Also:

String.valueOf(Object)

defaultIfEmpty

public static java.lang.String defaultIfEmpty(java.lang.String str,
                                              java.lang.String defaultStr)

Returns either the passed in String, or if the String is empty or null, the value of defaultStr.

 StringUtils.defaultIfEmpty(null, "NULL")  = "NULL"
 StringUtils.defaultIfEmpty("", "NULL")    = "NULL"
 StringUtils.defaultIfEmpty("bat", "NULL") = "bat"
 

Parameters:

str - the String to check, may be null

defaultStr - the default String to return if the input is empty ("") or null, may be null

Returns:

the passed in String, or the default

See Also:

defaultString(String, String)

defaultIfBlank

public static java.lang.String defaultIfBlank(java.lang.String str,
                                              java.lang.String defaultStr)

Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or null, the value of defaultStr.

 StringUtils.defaultIfBlank(null, "NULL")  = "NULL"
 StringUtils.defaultIfBlank("", "NULL")    = "NULL"
 StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"
 StringUtils.defaultIfBlank("bat", "NULL") = "bat"
 StringUtils.defaultIfBlank("", null)      = null
 

Parameters:

str - the CharSequence to check, may be null

defaultStr - the default CharSequence to return if the input is whitespace, empty ("") or null, may be null

Returns:

the passed in CharSequence, or the default

See Also:

defaultString(String, String)

isEmpty

public static boolean isEmpty(java.lang.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
 

NOTE: This method changed in Lang version 2.0. It no longer trims the String. That functionality is available in isBlank().

Parameters:

str - the String to check, may be null

Returns:

true if the String is empty or null

isBlank

public static boolean isBlank(java.lang.String str)

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

 StringUtils.isBlank(null)      = true
 StringUtils.isBlank("")        = true
 StringUtils.isBlank(" ")       = true
 StringUtils.isBlank("bob")     = false
 StringUtils.isBlank("  bob  ") = false
 

Parameters:

str - the String to check, may be null

Returns:

true if the String is null, empty or whitespace

Since:

2.0

countMatches

public static int countMatches(java.lang.String str,
                               java.lang.String sub)

Counts how many times the substring appears in the larger String.

A null or empty ("") String input returns 0.

 StringUtils.countMatches(null, *)       = 0
 StringUtils.countMatches("", *)         = 0
 StringUtils.countMatches("abba", null)  = 0
 StringUtils.countMatches("abba", "")    = 0
 StringUtils.countMatches("abba", "a")   = 2
 StringUtils.countMatches("abba", "ab")  = 1
 StringUtils.countMatches("abba", "xxx") = 0
 

Parameters:

str - the String to check, may be null

sub - the substring to count, may be null

Returns:

the number of occurrences, 0 if either String is null

rightPad

public static java.lang.String rightPad(java.lang.String str,
                                        int size)

Right pad a String with spaces (' ').

The String is padded to the size of size.

 StringUtils.rightPad(null, *)   = null
 StringUtils.rightPad("", 3)     = "   "
 StringUtils.rightPad("bat", 3)  = "bat"
 StringUtils.rightPad("bat", 5)  = "bat  "
 StringUtils.rightPad("bat", 1)  = "bat"
 StringUtils.rightPad("bat", -1) = "bat"
 

Parameters:

str - the String to pad out, may be null

size - the size to pad to

Returns:

right padded String or original String if no padding is necessary, null if null String input

rightPad

public static java.lang.String rightPad(java.lang.String str,
                                        int size,
                                        char padChar)

Right pad a String with a specified character.

The String is padded to the size of size.

 StringUtils.rightPad(null, *, *)     = null
 StringUtils.rightPad("", 3, 'z')     = "zzz"
 StringUtils.rightPad("bat", 3, 'z')  = "bat"
 StringUtils.rightPad("bat", 5, 'z')  = "batzz"
 StringUtils.rightPad("bat", 1, 'z')  = "bat"
 StringUtils.rightPad("bat", -1, 'z') = "bat"
 

Parameters:

str - the String to pad out, may be null

size - the size to pad to

padChar - the character to pad with

Returns:

right padded String or original String if no padding is necessary, null if null String input

Since:

2.0

rightPad

public static java.lang.String rightPad(java.lang.String str,
                                        int size,
                                        java.lang.String padStr)

Right pad a String with a specified String.

The String is padded to the size of size.

 StringUtils.rightPad(null, *, *)      = null
 StringUtils.rightPad("", 3, "z")      = "zzz"
 StringUtils.rightPad("bat", 3, "yz")  = "bat"
 StringUtils.rightPad("bat", 5, "yz")  = "batyz"
 StringUtils.rightPad("bat", 8, "yz")  = "batyzyzy"
 StringUtils.rightPad("bat", 1, "yz")  = "bat"
 StringUtils.rightPad("bat", -1, "yz") = "bat"
 StringUtils.rightPad("bat", 5, null)  = "bat  "
 StringUtils.rightPad("bat", 5, "")    = "bat  "
 

Parameters:

str - the String to pad out, may be null

size - the size to pad to

padStr - the String to pad with, null or empty treated as single space

Returns:

right padded String or original String if no padding is necessary, null if null String input

leftPad

public static java.lang.String leftPad(java.lang.String str,
                                       int size)

Left pad a String with spaces (' ').

The String is padded to the size of size.

 StringUtils.leftPad(null, *)   = null
 StringUtils.leftPad("", 3)     = "   "
 StringUtils.leftPad("bat", 3)  = "bat"
 StringUtils.leftPad("bat", 5)  = "  bat"
 StringUtils.leftPad("bat", 1)  = "bat"
 StringUtils.leftPad("bat", -1) = "bat"
 

Parameters:

str - the String to pad out, may be null

size - the size to pad to

Returns:

left padded String or original String if no padding is necessary, null if null String input

leftPad

public static java.lang.String leftPad(java.lang.String str,
                                       int size,
                                       char padChar)

Left pad a String with a specified character.

Pad to a size of size.

 StringUtils.leftPad(null, *, *)     = null
 StringUtils.leftPad("", 3, 'z')     = "zzz"
 StringUtils.leftPad("bat", 3, 'z')  = "bat"
 StringUtils.leftPad("bat", 5, 'z')  = "zzbat"
 StringUtils.leftPad("bat", 1, 'z')  = "bat"
 StringUtils.leftPad("bat", -1, 'z') = "bat"
 

Parameters:

str - the String to pad out, may be null

size - the size to pad to

padChar - the character to pad with

Returns:

left padded String or original String if no padding is necessary, null if null String input

Since:

2.0

leftPad

public static java.lang.String leftPad(java.lang.String str,
                                       int size,
                                       java.lang.String padStr)

Left pad a String with a specified String.

Pad to a size of size.

 StringUtils.leftPad(null, *, *)      = null
 StringUtils.leftPad("", 3, "z")      = "zzz"
 StringUtils.leftPad("bat", 3, "yz")  = "bat"
 StringUtils.leftPad("bat", 5, "yz")  = "yzbat"
 StringUtils.leftPad("bat", 8, "yz")  = "yzyzybat"
 StringUtils.leftPad("bat", 1, "yz")  = "bat"
 StringUtils.leftPad("bat", -1, "yz") = "bat"
 StringUtils.leftPad("bat", 5, null)  = "  bat"
 StringUtils.leftPad("bat", 5, "")    = "  bat"
 

Parameters:

str - the String to pad out, may be null

size - the size to pad to

padStr - the String to pad with, null or empty treated as single space

Returns:

left padded String or original String if no padding is necessary, null if null String input

abbreviate

public static java.lang.String abbreviate(java.lang.String str,
                                          int maxWidth)

Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "Now is the time for..."

Specifically:

• If str is less than maxWidth characters long, return it.
• Else abbreviate it to (substring(str, 0, max-3) + "...").
• If maxWidth is less than 4, throw an IllegalArgumentException.
• In no case will it return a String of length greater than maxWidth.

 StringUtils.abbreviate(null, *)      = null
 StringUtils.abbreviate("", 4)        = ""
 StringUtils.abbreviate("abcdefg", 6) = "abc..."
 StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 4) = "a..."
 StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
 

Parameters:

str - the String to check, may be null

maxWidth - maximum length of result String, must be at least 4

Returns:

abbreviated String, null if null String input

Throws:

java.lang.IllegalArgumentException - if the width is too small

Since:

2.0

abbreviate

public static java.lang.String abbreviate(java.lang.String str,
                                          int offset,
                                          int maxWidth)

Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "...is the time for..."

Works like abbreviate(String, int), but allows you to specify a "left edge" offset. Note that this left edge is not necessarily going to be the leftmost character in the result, or the first character following the ellipses, but it will appear somewhere in the result.

In no case will it return a String of length greater than maxWidth.

 StringUtils.abbreviate(null, *, *)                = null
 StringUtils.abbreviate("", 0, 4)                  = ""
 StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 0, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 1, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 4, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 5, 10)  = "...fghi..."
 StringUtils.abbreviate("abcdefghijklmno", 6, 10)  = "...ghij..."
 StringUtils.abbreviate("abcdefghijklmno", 8, 10)  = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghij", 0, 3)        = IllegalArgumentException
 StringUtils.abbreviate("abcdefghij", 5, 6)        = IllegalArgumentException
 

Parameters:

str - the String to check, may be null

offset - left edge of source String

maxWidth - maximum length of result String, must be at least 4

Returns:

abbreviated String, null if null String input

Throws:

java.lang.IllegalArgumentException - if the width is too small

Since:

2.0

containsAny

public static boolean containsAny(java.lang.String str,
                                  char... searchChars)

Checks if the String contains any character in the given set of characters.

A null String will return false. A null or zero length search array will return false.

 StringUtils.containsAny(null, *)                = false
 StringUtils.containsAny("", *)                  = false
 StringUtils.containsAny(*, null)                = false
 StringUtils.containsAny(*, [])                  = false
 StringUtils.containsAny("zzabyycdxx",['z','a']) = true
 StringUtils.containsAny("zzabyycdxx",['b','y']) = true
 StringUtils.containsAny("aba", ['z'])           = false
 

Parameters:

str - the String to check, may be null

searchChars - the chars to search for, may be null

Returns:

the true if any of the chars are found, false if no match or null input

Since:

2.4

replace

public static java.lang.String replace(java.lang.String text,
                                       java.lang.String searchString,
                                       java.lang.String replacement)

Replaces all occurrences of a String within another String.

A null reference passed to this method is a no-op.

 StringUtils.replace(null, *, *)        = null
 StringUtils.replace("", *, *)          = ""
 StringUtils.replace("any", null, *)    = "any"
 StringUtils.replace("any", *, null)    = "any"
 StringUtils.replace("any", "", *)      = "any"
 StringUtils.replace("aba", "a", null)  = "aba"
 StringUtils.replace("aba", "a", "")    = "b"
 StringUtils.replace("aba", "a", "z")   = "zbz"
 

Parameters:

text - text to search and replace in, may be null

searchString - the String to search for, may be null

replacement - the String to replace it with, may be null

Returns:

the text with any replacements processed, null if null String input

See Also:

replace(String text, String searchString, String replacement, int max)

replace

public static java.lang.String replace(java.lang.String text,
                                       java.lang.String searchString,
                                       java.lang.String replacement,
                                       int max)

Replaces a String with another String inside a larger String, for the first max values of the search String.

A null reference passed to this method is a no-op.

 StringUtils.replace(null, *, *, *)         = null
 StringUtils.replace("", *, *, *)           = ""
 StringUtils.replace("any", null, *, *)     = "any"
 StringUtils.replace("any", *, null, *)     = "any"
 StringUtils.replace("any", "", *, *)       = "any"
 StringUtils.replace("any", *, *, 0)        = "any"
 StringUtils.replace("abaa", "a", null, -1) = "abaa"
 StringUtils.replace("abaa", "a", "", -1)   = "b"
 StringUtils.replace("abaa", "a", "z", 0)   = "abaa"
 StringUtils.replace("abaa", "a", "z", 1)   = "zbaa"
 StringUtils.replace("abaa", "a", "z", 2)   = "zbza"
 StringUtils.replace("abaa", "a", "z", -1)  = "zbzz"
 

Parameters:

text - text to search and replace in, may be null

searchString - the String to search for, may be null

replacement - the String to replace it with, may be null

max - maximum number of values to replace, or -1 if no maximum

Returns:

the text with any replacements processed, null if null String input

replaceEach

public static java.lang.String replaceEach(java.lang.String text,
                                           java.lang.String[] searchList,
                                           java.lang.String[] replacementList)

Replaces all occurrences of Strings within another String.

A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored. This will not repeat. For repeating replaces, call the overloaded method.

  StringUtils.replaceEach(null, *, *)        = null
  StringUtils.replaceEach("", *, *)          = ""
  StringUtils.replaceEach("aba", null, null) = "aba"
  StringUtils.replaceEach("aba", new String[0], null) = "aba"
  StringUtils.replaceEach("aba", null, new String[0]) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, null)  = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""})  = "b"
  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"})  = "aba"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"})  = "wcte"
  (example of how it does not repeat)
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"})  = "dcte"
 

Parameters:

text - text to search and replace in, no-op if null

searchList - the Strings to search for, no-op if null

replacementList - the Strings to replace them with, no-op if null

Returns:

the text with any replacements processed, null if null String input

Throws:

java.lang.IndexOutOfBoundsException - if the lengths of the arrays are not the same (null is ok, and/or size 0)

Since:

2.4

join

public static <T> java.lang.String join(T... elements)

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

No separator is added to the joined 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"]) = "abc"
 StringUtils.join([null, "", "a"]) = "a"
 

Type Parameters:

T - the specific type of values to join together

Parameters:

elements - the values to join together, may be null

Returns:

the joined String, null if null array input

Since:

2.0, 3.0 Changed signature to use varargs

join

public static java.lang.String join(java.lang.Object[] array,
                                    char 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. 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([null, "", "a"], ';')  = ";;a"
 

Parameters:

array - the array of values to join together, may be null

separator - the separator character to use

Returns:

the joined String, null if null array input

Since:

2.0

join

public static java.lang.String join(java.lang.Object[] array,
                                    char 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. 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([null, "", "a"], ';')  = ";;a"
 

Parameters:

array - the array of values to join together, may be null

separator - the separator character to use

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

Since:

2.0

join

public static java.lang.String join(java.lang.Object[] array,
                                    java.lang.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 java.lang.String join(java.lang.Object[] array,
                                    java.lang.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

equals

public static boolean equals(java.lang.Object object1,
                             java.lang.Object object2)

Compares two objects for equality, where either one or both objects may be null.

 ObjectUtils.equals(null, null)                  = true
 ObjectUtils.equals(null, "")                    = false
 ObjectUtils.equals("", null)                    = false
 ObjectUtils.equals("", "")                      = true
 ObjectUtils.equals(Boolean.TRUE, null)          = false
 ObjectUtils.equals(Boolean.TRUE, "true")        = false
 ObjectUtils.equals(Boolean.TRUE, Boolean.TRUE)  = true
 ObjectUtils.equals(Boolean.TRUE, Boolean.FALSE) = false
 

Parameters:

object1 - the first object, may be null

object2 - the second object, may be null

Returns:

true if the values of both objects are the same

defaultIfNull

public static <T> T defaultIfNull(T object,
                                  T defaultValue)

Returns a default value if the object passed is null.

 ObjectUtils.defaultIfNull(null, null)      = null
 ObjectUtils.defaultIfNull(null, "")        = ""
 ObjectUtils.defaultIfNull(null, "zz")      = "zz"
 ObjectUtils.defaultIfNull("abc", *)        = "abc"
 ObjectUtils.defaultIfNull(Boolean.TRUE, *) = Boolean.TRUE
 

Type Parameters:

T - the type of the object

Parameters:

object - the Object to test, may be null

defaultValue - the default value to return, may be null

Returns:

object if it is not null, defaultValue otherwise

toCamelCase

public static java.lang.String toCamelCase(java.lang.String string)

Convert a string to camel case

toCamelCaseLC

public static java.lang.String toCamelCaseLC(java.lang.String string)

Convert a string to camel case starting with a lower case letter

toLC

public static java.lang.String toLC(java.lang.String string)

Change a string's first letter to lower case

split

public static java.lang.String[] split(java.lang.String regex,
                                       java.lang.CharSequence input)

A custom adaptation of Pattern.split(CharSequence, int).

This is useful if the matched split-tokens should be returned as well. For example:

 split("e", "hello world")    // ["h", "e", "llo world"]
 split("o", "hello world")    // ["hell", "o", " w", "o", "rld"]
 split("[eo]", "hello world") // ["h", "e", "ll", "o", " w", "o", "rld"]
 

The result will always be an odd-length array.