public abstract class

StringUtils

extends Object
java.lang.Object
   ↳ org.springframework.util.StringUtils

Class Overview

Miscellaneous String utility methods.

Mainly for internal use within the framework; consider Jakarta's Commons Lang for a more comprehensive suite of String utilities.

This class delivers some simple functionality that should really be provided by the core Java String and StringBuilder classes, such as the ability to replace(String, String, String) all occurrences of a given substring in a target string. It also provides easy-to-use methods to convert between delimited strings, such as CSV strings, and collections and arrays.

See Also
  • org.apache.commons.lang.StringUtils

Summary

Public Constructors
StringUtils()
Public Methods
static String[] addStringToArray(String[] array, String str)
Append the given String to the given String array, returning a new array consisting of the input array contents plus the given String.
static String applyRelativePath(String path, String relativePath)
Apply the given relative path to the given path, assuming standard Java folder separation (i.e.
static String arrayToCommaDelimitedString(Object[] arr)
Convenience method to return a String array as a CSV String.
static String arrayToDelimitedString(Object[] arr, String delim)
Convenience method to return a String array as a delimited (e.g.
static String capitalize(String str)
Capitalize a String, changing the first letter to upper case as per toUpperCase(char).
static String cleanPath(String path)
Normalize the path by suppressing sequences like "path/.." and inner simple dots.
static String collectionToCommaDelimitedString(Collection coll)
Convenience method to return a Collection as a CSV String.
static String collectionToDelimitedString(Collection coll, String delim, String prefix, String suffix)
Convenience method to return a Collection as a delimited (e.g.
static String collectionToDelimitedString(Collection coll, String delim)
Convenience method to return a Collection as a delimited (e.g.
static Set<String> commaDelimitedListToSet(String str)
Convenience method to convert a CSV string list to a set.
static String[] commaDelimitedListToStringArray(String str)
Convert a CSV list into an array of Strings.
static String[] concatenateStringArrays(String[] array1, String[] array2)
Concatenate the given String arrays into one, with overlapping array elements included twice.
static boolean containsWhitespace(String str)
Check whether the given String contains any whitespace characters.
static boolean containsWhitespace(CharSequence str)
Check whether the given CharSequence contains any whitespace characters.
static int countOccurrencesOf(String str, String sub)
Count the occurrences of the substring in string s.
static String delete(String inString, String pattern)
Delete all occurrences of the given substring.
static String deleteAny(String inString, String charsToDelete)
Delete any character in a given String.
static String[] delimitedListToStringArray(String str, String delimiter)
Take a String which is a delimited list and convert it to a String array.
static String[] delimitedListToStringArray(String str, String delimiter, String charsToDelete)
Take a String which is a delimited list and convert it to a String array.
static boolean endsWithIgnoreCase(String str, String suffix)
Test if the given String ends with the specified suffix, ignoring upper/lower case.
static String getFilename(String path)
Extract the filename from the given path, e.g.
static String getFilenameExtension(String path)
Extract the filename extension from the given path, e.g.
static boolean hasLength(CharSequence str)
Check that the given CharSequence is neither null nor of length 0.
static boolean hasLength(String str)
Check that the given String is neither null nor of length 0.
static boolean hasText(String str)
Check whether the given String has actual text.
static boolean hasText(CharSequence str)
Check whether the given CharSequence has actual text.
static String[] mergeStringArrays(String[] array1, String[] array2)
Merge the given String arrays into one, with overlapping array elements only included once.
static Locale parseLocaleString(String localeString)
Parse the given localeString value into a Locale.
static boolean pathEquals(String path1, String path2)
Compare two paths after normalization of them.
static String quote(String str)
Quote the given String with single quotes.
static Object quoteIfString(Object obj)
Turn the given Object into a String with single quotes if it is a String; keeping the Object as-is else.
static String[] removeDuplicateStrings(String[] array)
Remove duplicate Strings from the given array.
static String replace(String inString, String oldPattern, String newPattern)
Replace all occurences of a substring within a string with another string.
static String[] sortStringArray(String[] array)
Turn given source String array into sorted array.
static String[] split(String toSplit, String delimiter)
Split a String at the first occurrence of the delimiter.
static Properties splitArrayElementsIntoProperties(String[] array, String delimiter, String charsToDelete)
Take an array Strings and split each element based on the given delimiter.
static Properties splitArrayElementsIntoProperties(String[] array, String delimiter)
Take an array Strings and split each element based on the given delimiter.
static boolean startsWithIgnoreCase(String str, String prefix)
Test if the given String starts with the specified prefix, ignoring upper/lower case.
static String stripFilenameExtension(String path)
Strip the filename extension from the given path, e.g.
static boolean substringMatch(CharSequence str, int index, CharSequence substring)
Test whether the given string matches the given substring at the given index.
static String toLanguageTag(Locale locale)
Determine the RFC 3066 compliant language tag, as used for the HTTP "Accept-Language" header.
static String[] toStringArray(Enumeration<String> enumeration)
Copy the given Enumeration into a String array.
static String[] toStringArray(Collection<String> collection)
Copy the given Collection into a String array.
static String[] tokenizeToStringArray(String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens)
Tokenize the given String into a String array via a StringTokenizer.
static String[] tokenizeToStringArray(String str, String delimiters)
Tokenize the given String into a String array via a StringTokenizer.
static String trimAllWhitespace(String str)
Trim all whitespace from the given String: leading, trailing, and inbetween characters.
static String[] trimArrayElements(String[] array)
Trim the elements of the given String array, calling String.trim() on each of them.
static String trimLeadingCharacter(String str, char leadingCharacter)
Trim all occurences of the supplied leading character from the given String.
static String trimLeadingWhitespace(String str)
Trim leading whitespace from the given String.
static String trimTrailingCharacter(String str, char trailingCharacter)
Trim all occurences of the supplied trailing character from the given String.
static String trimTrailingWhitespace(String str)
Trim trailing whitespace from the given String.
static String trimWhitespace(String str)
Trim leading and trailing whitespace from the given String.
static String uncapitalize(String str)
Uncapitalize a String, changing the first letter to lower case as per toLowerCase(char).
static String unqualify(String qualifiedName, char separator)
Unqualify a string qualified by a separator character.
static String unqualify(String qualifiedName)
Unqualify a string qualified by a '.' dot character.
[Expand]
Inherited Methods
From class java.lang.Object

Public Constructors

public StringUtils ()

Also: SpringCore

Public Methods

public static String[] addStringToArray (String[] array, String str)

Also: SpringCore

Append the given String to the given String array, returning a new array consisting of the input array contents plus the given String.

Parameters
array the array to append to (can be null)
str the String to append
Returns
  • the new array (never null)

public static String applyRelativePath (String path, String relativePath)

Also: SpringCore

Apply the given relative path to the given path, assuming standard Java folder separation (i.e. "/" separators).

Parameters
path the path to start from (usually a full file path)
relativePath the relative path to apply (relative to the full file path above)
Returns
  • the full file path that results from applying the relative path

public static String arrayToCommaDelimitedString (Object[] arr)

Also: SpringCore

Convenience method to return a String array as a CSV String. E.g. useful for toString() implementations.

Parameters
arr the array to display
Returns
  • the delimited String

public static String arrayToDelimitedString (Object[] arr, String delim)

Also: SpringCore

Convenience method to return a String array as a delimited (e.g. CSV) String. E.g. useful for toString() implementations.

Parameters
arr the array to display
delim the delimiter to use (probably a ",")
Returns
  • the delimited String

public static String capitalize (String str)

Also: SpringCore

Capitalize a String, changing the first letter to upper case as per toUpperCase(char). No other letters are changed.

Parameters
str the String to capitalize, may be null
Returns
  • the capitalized String, null if null

public static String cleanPath (String path)

Also: SpringCore

Normalize the path by suppressing sequences like "path/.." and inner simple dots.

The result is convenient for path comparison. For other uses, notice that Windows separators ("\") are replaced by simple slashes.

Parameters
path the original path
Returns
  • the normalized path

public static String collectionToCommaDelimitedString (Collection coll)

Also: SpringCore

Convenience method to return a Collection as a CSV String. E.g. useful for toString() implementations.

Parameters
coll the Collection to display
Returns
  • the delimited String

public static String collectionToDelimitedString (Collection coll, String delim, String prefix, String suffix)

Also: SpringCore

Convenience method to return a Collection as a delimited (e.g. CSV) String. E.g. useful for toString() implementations.

Parameters
coll the Collection to display
delim the delimiter to use (probably a ",")
prefix the String to start each element with
suffix the String to end each element with
Returns
  • the delimited String

public static String collectionToDelimitedString (Collection coll, String delim)

Also: SpringCore

Convenience method to return a Collection as a delimited (e.g. CSV) String. E.g. useful for toString() implementations.

Parameters
coll the Collection to display
delim the delimiter to use (probably a ",")
Returns
  • the delimited String

public static Set<String> commaDelimitedListToSet (String str)

Also: SpringCore

Convenience method to convert a CSV string list to a set. Note that this will suppress duplicates.

Parameters
str the input String
Returns
  • a Set of String entries in the list

public static String[] commaDelimitedListToStringArray (String str)

Also: SpringCore

Convert a CSV list into an array of Strings.

Parameters
str the input String
Returns
  • an array of Strings, or the empty array in case of empty input

public static String[] concatenateStringArrays (String[] array1, String[] array2)

Also: SpringCore

Concatenate the given String arrays into one, with overlapping array elements included twice.

The order of elements in the original arrays is preserved.

Parameters
array1 the first array (can be null)
array2 the second array (can be null)
Returns
  • the new array (null if both given arrays were null)

public static boolean containsWhitespace (String str)

Also: SpringCore

Check whether the given String contains any whitespace characters.

Parameters
str the String to check (may be null)
Returns
  • true if the String is not empty and contains at least 1 whitespace character
See Also

public static boolean containsWhitespace (CharSequence str)

Also: SpringCore

Check whether the given CharSequence contains any whitespace characters.

Parameters
str the CharSequence to check (may be null)
Returns
  • true if the CharSequence is not empty and contains at least 1 whitespace character
See Also

public static int countOccurrencesOf (String str, String sub)

Also: SpringCore

Count the occurrences of the substring in string s.

Parameters
str string to search in. Return 0 if this is null.
sub string to search for. Return 0 if this is null.

public static String delete (String inString, String pattern)

Also: SpringCore

Delete all occurrences of the given substring.

Parameters
inString the original String
pattern the pattern to delete all occurrences of
Returns
  • the resulting String

public static String deleteAny (String inString, String charsToDelete)

Also: SpringCore

Delete any character in a given String.

Parameters
inString the original String
charsToDelete a set of characters to delete. E.g. "az\n" will delete 'a's, 'z's and new lines.
Returns
  • the resulting String

public static String[] delimitedListToStringArray (String str, String delimiter)

Also: SpringCore

Take a String which is a delimited list and convert it to a String array.

A single delimiter can consists of more than one character: It will still be considered as single delimiter string, rather than as bunch of potential delimiter characters - in contrast to tokenizeToStringArray.

Parameters
str the input String
delimiter the delimiter between elements (this is a single delimiter, rather than a bunch individual delimiter characters)
Returns
  • an array of the tokens in the list
See Also

public static String[] delimitedListToStringArray (String str, String delimiter, String charsToDelete)

Also: SpringCore

Take a String which is a delimited list and convert it to a String array.

A single delimiter can consists of more than one character: It will still be considered as single delimiter string, rather than as bunch of potential delimiter characters - in contrast to tokenizeToStringArray.

Parameters
str the input String
delimiter the delimiter between elements (this is a single delimiter, rather than a bunch individual delimiter characters)
charsToDelete a set of characters to delete. Useful for deleting unwanted line breaks: e.g. "\r\n\f" will delete all new lines and line feeds in a String.
Returns
  • an array of the tokens in the list
See Also

public static boolean endsWithIgnoreCase (String str, String suffix)

Also: SpringCore

Test if the given String ends with the specified suffix, ignoring upper/lower case.

Parameters
str the String to check
suffix the suffix to look for
See Also

public static String getFilename (String path)

Also: SpringCore

Extract the filename from the given path, e.g. "mypath/myfile.txt" -> "myfile.txt".

Parameters
path the file path (may be null)
Returns
  • the extracted filename, or null if none

public static String getFilenameExtension (String path)

Also: SpringCore

Extract the filename extension from the given path, e.g. "mypath/myfile.txt" -> "txt".

Parameters
path the file path (may be null)
Returns
  • the extracted filename extension, or null if none

public static boolean hasLength (CharSequence str)

Also: SpringCore

Check that the given CharSequence is neither null nor of length 0. Note: Will return true for a CharSequence that purely consists of whitespace. 

 StringUtils.hasLength(null) = false
 StringUtils.hasLength("") = false
 StringUtils.hasLength(" ") = true
 StringUtils.hasLength("Hello") = true

Parameters
str the CharSequence to check (may be null)
Returns
  • true if the CharSequence is not null and has length
See Also

public static boolean hasLength (String str)

Also: SpringCore

Check that the given String is neither null nor of length 0. Note: Will return true for a String that purely consists of whitespace.

Parameters
str the String to check (may be null)
Returns
  • true if the String is not null and has length
See Also

public static boolean hasText (String str)

Also: SpringCore

Check whether the given String has actual text. More specifically, returns true if the string not null, its length is greater than 0, and it contains at least one non-whitespace character.

Parameters
str the String to check (may be null)
Returns
  • true if the String is not null, its length is greater than 0, and it does not contain whitespace only
See Also

public static boolean hasText (CharSequence str)

Also: SpringCore

Check whether the given CharSequence has actual text. More specifically, returns true if the string not null, its length is greater than 0, and it contains at least one non-whitespace character. 

 StringUtils.hasText(null) = false
 StringUtils.hasText("") = false
 StringUtils.hasText(" ") = false
 StringUtils.hasText("12345") = true
 StringUtils.hasText(" 12345 ") = true

Parameters
str the CharSequence to check (may be null)
Returns
  • true if the CharSequence is not null, its length is greater than 0, and it does not contain whitespace only
See Also

public static String[] mergeStringArrays (String[] array1, String[] array2)

Also: SpringCore

Merge the given String arrays into one, with overlapping array elements only included once.

The order of elements in the original arrays is preserved (with the exception of overlapping elements, which are only included on their first occurence).

Parameters
array1 the first array (can be null)
array2 the second array (can be null)
Returns
  • the new array (null if both given arrays were null)

public static Locale parseLocaleString (String localeString)

Also: SpringCore

Parse the given localeString value into a Locale.

This is the inverse operation of Locale's toString.

Parameters
localeString the locale string, following Locale's toString() format ("en", "en_UK", etc); also accepts spaces as separators, as an alternative to underscores
Returns
  • a corresponding Locale instance

public static boolean pathEquals (String path1, String path2)

Also: SpringCore

Compare two paths after normalization of them.

Parameters
path1 first path for comparison
path2 second path for comparison
Returns
  • whether the two paths are equivalent after normalization

public static String quote (String str)

Also: SpringCore

Quote the given String with single quotes.

Parameters
str the input String (e.g. "myString")
Returns
  • the quoted String (e.g. "'myString'"), or null if the input was null

public static Object quoteIfString (Object obj)

Also: SpringCore

Turn the given Object into a String with single quotes if it is a String; keeping the Object as-is else.

Parameters
obj the input Object (e.g. "myString")
Returns
  • the quoted String (e.g. "'myString'"), or the input object as-is if not a String

public static String[] removeDuplicateStrings (String[] array)

Also: SpringCore

Remove duplicate Strings from the given array. Also sorts the array, as it uses a TreeSet.

Parameters
array the String array
Returns
  • an array without duplicates, in natural sort order

public static String replace (String inString, String oldPattern, String newPattern)

Also: SpringCore

Replace all occurences of a substring within a string with another string.

Parameters
inString String to examine
oldPattern String to replace
newPattern String to insert
Returns
  • a String with the replacements

public static String[] sortStringArray (String[] array)

Also: SpringCore

Turn given source String array into sorted array.

Parameters
array the source array
Returns
  • the sorted array (never null)

public static String[] split (String toSplit, String delimiter)

Also: SpringCore

Split a String at the first occurrence of the delimiter. Does not include the delimiter in the result.

Parameters
toSplit the string to split
delimiter to split the string up with
Returns
  • a two element array with index 0 being before the delimiter, and index 1 being after the delimiter (neither element includes the delimiter); or null if the delimiter wasn't found in the given input String

public static Properties splitArrayElementsIntoProperties (String[] array, String delimiter, String charsToDelete)

Also: SpringCore

Take an array Strings and split each element based on the given delimiter. A Properties instance is then generated, with the left of the delimiter providing the key, and the right of the delimiter providing the value.

Will trim both the key and value before adding them to the Properties instance.

Parameters
array the array to process
delimiter to split each element using (typically the equals symbol)
charsToDelete one or more characters to remove from each element prior to attempting the split operation (typically the quotation mark symbol), or null if no removal should occur
Returns
  • a Properties instance representing the array contents, or null if the array to process was null or empty

public static Properties splitArrayElementsIntoProperties (String[] array, String delimiter)

Also: SpringCore

Take an array Strings and split each element based on the given delimiter. A Properties instance is then generated, with the left of the delimiter providing the key, and the right of the delimiter providing the value.

Will trim both the key and value before adding them to the Properties instance.

Parameters
array the array to process
delimiter to split each element using (typically the equals symbol)
Returns
  • a Properties instance representing the array contents, or null if the array to process was null or empty

public static boolean startsWithIgnoreCase (String str, String prefix)

Also: SpringCore

Test if the given String starts with the specified prefix, ignoring upper/lower case.

Parameters
str the String to check
prefix the prefix to look for
See Also

public static String stripFilenameExtension (String path)

Also: SpringCore

Strip the filename extension from the given path, e.g. "mypath/myfile.txt" -> "mypath/myfile".

Parameters
path the file path (may be null)
Returns
  • the path with stripped filename extension, or null if none

public static boolean substringMatch (CharSequence str, int index, CharSequence substring)

Also: SpringCore

Test whether the given string matches the given substring at the given index.

Parameters
str the original string (or StringBuilder)
index the index in the original string to start matching against
substring the substring to match at the given index

public static String toLanguageTag (Locale locale)

Also: SpringCore

Determine the RFC 3066 compliant language tag, as used for the HTTP "Accept-Language" header.

Parameters
locale the Locale to transform to a language tag
Returns
  • the RFC 3066 compliant language tag as String

public static String[] toStringArray (Enumeration<String> enumeration)

Also: SpringCore

Copy the given Enumeration into a String array. The Enumeration must contain String elements only.

Parameters
enumeration the Enumeration to copy
Returns
  • the String array (null if the passed-in Enumeration was null)

public static String[] toStringArray (Collection<String> collection)

Also: SpringCore

Copy the given Collection into a String array. The Collection must contain String elements only.

Parameters
collection the Collection to copy
Returns
  • the String array (null if the passed-in Collection was null)

public static String[] tokenizeToStringArray (String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens)

Also: SpringCore

Tokenize the given String into a String array via a StringTokenizer.

The given delimiters string is supposed to consist of any number of delimiter characters. Each of those characters can be used to separate tokens. A delimiter is always a single character; for multi-character delimiters, consider using delimitedListToStringArray

Parameters
str the String to tokenize
delimiters the delimiter characters, assembled as String (each of those characters is individually considered as delimiter)
trimTokens trim the tokens via String's trim
ignoreEmptyTokens omit empty tokens from the result array (only applies to tokens that are empty after trimming; StringTokenizer will not consider subsequent delimiters as token in the first place).
Returns
  • an array of the tokens (null if the input String was null)
See Also

public static String[] tokenizeToStringArray (String str, String delimiters)

Also: SpringCore

Tokenize the given String into a String array via a StringTokenizer. Trims tokens and omits empty tokens.

The given delimiters string is supposed to consist of any number of delimiter characters. Each of those characters can be used to separate tokens. A delimiter is always a single character; for multi-character delimiters, consider using delimitedListToStringArray

Parameters
str the String to tokenize
delimiters the delimiter characters, assembled as String (each of those characters is individually considered as delimiter).
Returns
  • an array of the tokens
See Also

public static String trimAllWhitespace (String str)

Also: SpringCore

Trim all whitespace from the given String: leading, trailing, and inbetween characters.

Parameters
str the String to check
Returns
  • the trimmed String
See Also

public static String[] trimArrayElements (String[] array)

Also: SpringCore

Trim the elements of the given String array, calling String.trim() on each of them.

Parameters
array the original String array
Returns
  • the resulting array (of the same size) with trimmed elements

public static String trimLeadingCharacter (String str, char leadingCharacter)

Also: SpringCore

Trim all occurences of the supplied leading character from the given String.

Parameters
str the String to check
leadingCharacter the leading character to be trimmed
Returns
  • the trimmed String

public static String trimLeadingWhitespace (String str)

Also: SpringCore

Trim leading whitespace from the given String.

Parameters
str the String to check
Returns
  • the trimmed String
See Also

public static String trimTrailingCharacter (String str, char trailingCharacter)

Also: SpringCore

Trim all occurences of the supplied trailing character from the given String.

Parameters
str the String to check
trailingCharacter the trailing character to be trimmed
Returns
  • the trimmed String

public static String trimTrailingWhitespace (String str)

Also: SpringCore

Trim trailing whitespace from the given String.

Parameters
str the String to check
Returns
  • the trimmed String
See Also

public static String trimWhitespace (String str)

Also: SpringCore

Trim leading and trailing whitespace from the given String.

Parameters
str the String to check
Returns
  • the trimmed String
See Also

public static String uncapitalize (String str)

Also: SpringCore

Uncapitalize a String, changing the first letter to lower case as per toLowerCase(char). No other letters are changed.

Parameters
str the String to uncapitalize, may be null
Returns
  • the uncapitalized String, null if null

public static String unqualify (String qualifiedName, char separator)

Also: SpringCore

Unqualify a string qualified by a separator character. For example, "this:name:is:qualified" returns "qualified" if using a ':' separator.

Parameters
qualifiedName the qualified name
separator the separator

public static String unqualify (String qualifiedName)

Also: SpringCore

Unqualify a string qualified by a '.' dot character. For example, "this.name.is.qualified", returns "qualified".

Parameters
qualifiedName the qualified name