A string of characters. Each character in the string is a 32-bit Unicode character. The internal UTF-16 encoding is hidden from clients.
Literal strings may be written between double quotes:
"hello world" "\r\n" "\{#03C0} \{#2248} 3.14159" "\{GREEK SMALL LETTER PI} \{ALMOST EQUAL TO} 3.14159"
Alternatively, a verbatim string may be written between tripled double quotes.
The empty string, ""
, is a string with no characters.
A string is a Category
of its characters
, and of
its substrings:
'w' in greeting "hello" in greeting
Strings are summable:
String greeting = "hello" + " " + "world";
They are efficiently iterable:
for (char in "hello world") { ... }
They are lists of characters:
value char = "hello world"[5];
They are ranged:
String who = "hello world"[6...];
Note that since string[index]
evaluates to the optional
type Character?
, it is often more convenient to write
string[index..index]
, which evaluates to a String
containing a single character, or to the empty string
""
if index
refers to a position outside the string.
It is easy to use comprehensions to transform strings:
String { for (s in "hello world") if (s.letter) s.uppercased }
Since a String
has an underlying UTF-16 encoding,
certain operations are expensive, requiring iteration of
the characters of the string. In particular, size
requires iteration of the whole string, and get()
,
span()
, and measure()
require iteration from the
beginning of the string to the given index.
no subtypes hierarchy
Initializer |
String({Character*} characters) Parameters:
|
Attributes | |
coalesced | shared actual String coalesced This string. Refines Iterable.coalesced |
empty | shared actual Boolean empty |
first | shared actual Character? first The first character in the string. |
hash | shared actual Integer hash The hash value of the value, which allows the value to be an element of a hash-based set or key of a hash-based map. Implementations must respect the constraint that:
Therefore, a class which refines Because the |
keys | shared actual Integer[] keys A sequence containing all indexes of this string. |
last | shared actual Character? last The last character in the string. |
lastIndex | shared actual Integer? lastIndex The index of the last character in the string, or
string.lastIndex == string.size-1 Refines List.lastIndex |
lines | shared {String*} lines Split the string into lines of text, discarding line
breaks. Recognized line break sequences are See also linesWithBreaks |
linesWithBreaks | shared {String*} linesWithBreaks Split the string into lines of text with line breaks.
Each line will be terminated by a line break sequence,
See also lines |
lowercased | shared String lowercased This string, with all characters in lowercase. Conversion of uppercase characters to lowercase is
performed according to a locale-independent mapping
that produces incorrect results in certain locales
(e.g. The resulting string may not have the same number of characters as this string, since the uppercase representation of certain characters comprises multiple characters, for example the lowercase representation of İ is two characters wide. |
normalized | shared String normalized A string containing the characters of this string after collapsing strings of whitespace into single space characters and discarding whitespace from the beginning and end of the string. |
rest | shared actual String rest The rest of the string, without its first character. |
reversed | shared actual String reversed A string containing the characters of this string, with the characters in reverse order. Refines List.reversed |
size | shared actual Integer size The length of the string (the number of characters it
contains). In the case of the empty string, the string
has length zero. Note that this operation is
potentially costly for long strings, since the
underlying representation of the characters uses a
UTF-16 encoding. Use of See also longerThan() , shorterThan() |
string | shared actual String string This string. |
trimmed | shared String trimmed A string containing the characters of this string, after discarding whitespace from the beginning and end of the string. |
uppercased | shared String uppercased This string, with all characters in uppercase. Conversion of lowercase characters to uppercase is
performed according to a locale-independent mapping
that produces incorrect results in certain locales
(e.g. The resulting string may not have the same number of characters as this string, since the uppercase representation of certain characters comprises multiple characters, for example the uppercase representation of ß is SS. |
Inherited Attributes |
Attributes inherited from: Object |
Attributes inherited from: Collection<Element> |
Attributes inherited from: Correspondence<Key,Item> |
Attributes inherited from: Iterable<Element,Absent> |
Attributes inherited from: List<Element> |
Methods | |
any | shared actual Boolean any(Boolean selecting(Character element)) Determines if there is at least one element of this
stream that satisfies the given predicate
function. If the stream is empty, returns
Refines Iterable.any |
clone | shared actual String clone() This string. |
compare | shared actual Comparison compare(String other) Compare this string with the given string lexicographically, according to the Unicode code points of the characters. This defines a locale-independent collation that is incorrect in some locales. Refines Comparable.compare |
compareIgnoringCase | shared Comparison compareIgnoringCase(String other) Compare this string with the given string
lexicographically, ignoring the case of the characters.
That is, by considering two characters
This defines a locale-independent collation that is incorrect in some locales. See also Character.lowercased , Character.uppercased |
contains | shared actual Boolean contains(Object element) Determines if the given object is a |
copyTo | shared void copyTo(Array<Character> destination, Integer sourcePosition = 0, Integer destinationPosition = 0, Integer length = ...) Efficiently copy the characters in the segment
Parameters:
|
count | shared actual Integer count(Boolean selecting(Character element)) Produces the number of elements in this stream that satisfy the given predicate function. For an infinite stream, this method never terminates. Refines Iterable.count |
defines | shared actual Boolean defines(Integer index) Determines if this string contains a character at the
given |
each | shared actual void each(void step(Character element)) Call the given function for each element of this stream, passing the elements in the order they occur in this stream. For example: words.each((word) { print(word.lowercased); print(word.uppercased); }); Has the same effect as the following for (word in words) { print(word.lowercased); print(word.uppercased); } For certain streams this method is highly efficient,
surpassing the performance of Refines Iterable.each |
endsWith | shared actual Boolean endsWith(List<Anything> substring) Determine if the given list occurs at the end of this list. Refines List.endsWith |
equals | shared actual Boolean equals(Object that) Determines if the given object is a |
equalsIgnoringCase | shared Boolean equalsIgnoringCase(String that) Compare this string with the given string, ignoring the
case of the characters. That is, by considering two
characters
See also Character.lowercased , Character.uppercased |
every | shared actual Boolean every(Boolean selecting(Character element)) Determines if all elements of this stream satisfy the
given predicate function. If the stream
is empty, return Refines Iterable.every |
find | shared actual Character? find(Boolean selecting(Character element)) The first element of this stream which satisfies the
given predicate function, if any, or
For example, the expression (-10..10).find(Integer.positive) evaluates to |
findLast | shared actual Character? findLast(Boolean selecting(Character element)) The last element of this stream which satisfies the
given predicate function, if any, or
For example, the expression (-10..10).findLast(3.divides) evaluates to |
firstInclusion | shared actual Integer? firstInclusion(List<Character> sublist, Integer from) The first index in this list at which the given list occurs as a sublist, that is greater than or equal to the optional starting index. Refines SearchableList.firstInclusion |
firstIndexWhere | shared actual Integer? firstIndexWhere(Boolean selecting(Character element)) The first index in this list for which the element is not null and satisfies the given predicate function. Refines List.firstIndexWhere |
firstOccurrence | shared actual Integer? firstOccurrence(Character element, Integer from, Integer length) The first index in this list at which the given
value occurs, that falls within the segment
Refines SearchableList.firstOccurrence |
getFromFirst | shared actual Character? getFromFirst(Integer index) Returns the character at the given |
getFromLast | shared actual Character? getFromLast(Integer index) Get the character at the specified index, where the
string is indexed from the end of the string, or
Refines List.getFromLast |
includes | shared actual Boolean includes(List<Character> sublist, Integer from) Determine if the given list occurs as a sublist at some index in this list, at any index that is greater than or equal to the optional starting index. Refines SearchableList.includes |
includesAt | shared actual Boolean includesAt(Integer index, List<Character> sublist) Determine if the given list occurs as a sublist at the given index of this list. Refines SearchableList.includesAt |
inclusions | shared actual {Integer*} inclusions(List<Character> sublist, Integer from) The indexes in this list at which the given list occurs as a sublist, that are greater than or equal to the optional starting index. Refines SearchableList.inclusions |
indexesWhere | shared actual {Integer*} indexesWhere(Boolean selecting(Character element)) The indexes in this list for which the element is not null and satisfies the given predicate function. Refines List.indexesWhere |
initial | shared actual String initial(Integer length) Select the first characters of this string, returning a
string no longer than the given Refines List.initial |
iterator | shared actual Iterator<Character> iterator() An iterator for the characters of the string. |
join | shared String join({Object*} objects) Join the string representations of
the given |
largerThan | shared actual Boolean largerThan(String other) Determines if this value is strictly larger than the given value. Refines Comparable.largerThan |
lastInclusion | shared actual Integer? lastInclusion(List<Character> sublist, Integer from) The last index in this list at which the given
list occurs as a sublist, that falls within
the range Refines SearchableList.lastInclusion |
lastIndexWhere | shared actual Integer? lastIndexWhere(Boolean selecting(Character element)) The last index in this list for which the element is not null and satisfies the given predicate function. Refines List.lastIndexWhere |
lastOccurrence | shared actual Integer? lastOccurrence(Character element, Integer from, Integer length) The last index in this list at which the given
value occurs, that falls within the range
Refines SearchableList.lastOccurrence |
locate | shared actual <Integer->Character>? locate(Boolean selecting(Character element)) The first element of this stream which satisfies the
given predicate function, if any,
together with its position in the stream, or For example, the expression (-10..10).locate(Integer.positive) evaluates to Refines Iterable.locate |
locateLast | shared actual <Integer->Character>? locateLast(Boolean selecting(Character element)) The last element of this stream which satisfies the
given predicate function, if any,
together with its position in the stream, or For example, the expression (-10..10).locateLast(3.divides) evaluates to Refines Iterable.locateLast |
locations | shared actual {<Integer->Character>*} locations(Boolean selecting(Character element)) A stream producing all elements of this stream which satisfy the given predicate function, together with their positions in the stream. For example, the expression (-5..5).locations(3.divides) evaluates to the stream Note that this method is more efficient than the
alternative of applying Refines Iterable.locations |
longerThan | shared actual Boolean longerThan(Integer length) |
measure | shared actual String measure(Integer from, Integer length) A string containing the characters of this string
beginning at the given start index, returning
a string no longer than the given |
notLargerThan | shared actual Boolean notLargerThan(String other) Determines if this value is smaller than or equal to the given value. Refines Comparable.notLargerThan |
notSmallerThan | shared actual Boolean notSmallerThan(String other) Determines if this value is larger than or equal to the given value. Refines Comparable.notSmallerThan |
occurrences | shared actual {Integer*} occurrences(Character element, Integer from, Integer length) The indexes in this list at which the given value occurs. Refines SearchableList.occurrences |
occurs | shared actual Boolean occurs(Character element, Integer from, Integer length) Determines if the given value occurs as an
element of this list, at any index that falls within
the segment Refines SearchableList.occurs |
occursAt | shared actual Boolean occursAt(Integer index, Character element) Determines if the given value occurs at the given index in this list. Refines SearchableList.occursAt |
pad | shared String pad(Integer size, Character character = ...) |
padLeading | shared String padLeading(Integer size, Character character = ...) |
padTrailing | shared String padTrailing(Integer size, Character character = ...) |
plus | shared actual String plus(String other) Returns the concatenation of this string with the given string. Refines Summable.plus |
reduce | shared actual Result|Character|Null reduce<Result>(Result accumulating(Result|Character partial, Character element)) Beginning with the For an empty stream, For a stream with one element, { first }.reduce(f) == first For a given stream it.reduce(f) == f(it.exceptLast.reduce(f), it.last) For example, the expression (1..100).reduce(plus<Integer>) results in the integer Refines Iterable.reduce |
repeat | shared actual String repeat(Integer times) Returns a string formed by repeating this string the
given number of |
replace | shared String replace(String substring, String replacement) Returns a string formed by replacing every occurrence
in this string of the given |
replaceFirst | shared String replaceFirst(String substring, String replacement) Returns a string formed by replacing the first
occurrence in this string of the given |
replaceLast | shared String replaceLast(String substring, String replacement) Returns a string formed by replacing the last
occurrence in this string of the given |
shorterThan | shared actual Boolean shorterThan(Integer length) |
slice | shared actual String[2] slice(Integer index) Return two strings, the first containing the characters
that occur before the given Refines List.slice |
smallerThan | shared actual Boolean smallerThan(String other) Determines if this value is strictly smaller than the given value. Refines Comparable.smallerThan |
span | shared actual String span(Integer from, Integer to) A string containing the characters of this string between the given indexes. If the start index is the same as the end index, return a string with a single character. If the start index is larger than the end index, return the characters in the reverse order from the order in which they appear in this string. If both the start index and the end index are larger than the last index in the string, or if both the start index and the end index are smaller than the first index in the string, return the empty string. Otherwise, if the last index is larger than the last index in the string, return all characters from the start index to last character of the string. |
spanFrom | shared actual String spanFrom(Integer from) A string containing the characters of this string from the given start index inclusive to the end of the string. If the start index is larger than the last index of the string, return the empty string. If the start index is negative, return this string. |
spanTo | shared actual String spanTo(Integer to) A string containing the characters of this string from the start of the string up to and including the given end index. If the end index is negative, return the empty string. If the end index is larger than the last index in this string, return this string. |
split | shared {String+} split(Boolean splitting(Character ch) = ..., Boolean discardSeparators = true, Boolean groupSeparators = true) Split the string into tokens, using the given predicate function to determine which characters are separator characters. value pathElements = path.split('/'.equals); The flags Note that for the case of the empty string, "".split('/'.equals) evaluates to the nonempty stream Parameters:
|
startsWith | shared actual Boolean startsWith(List<Anything> substring) Determine if the given list occurs at the start of this list. Refines List.startsWith |
sublistFrom | shared actual List<Character> sublistFrom(Integer from) A sublist of this list, starting at the element with the given index. This is a lazy operation, returning a view of this list. Refines List.sublistFrom |
sublistTo | shared actual List<Character> sublistTo(Integer to) A sublist of this list, ending at the element with the given index. This is a lazy operation, returning a view of this list. Refines List.sublistTo |
terminal | shared actual String terminal(Integer length) Select the last characters of the string, returning a
string no longer than the given Refines List.terminal |
trim | shared actual String trim(Boolean trimming(Character element)) A string containing the characters of this string, after discarding the characters matching the given predicate function from the beginning and end of the string. value trimmed = name.trim('_'.equals); A character is removed from the string if it matches the given predicate and if either:
Refines List.trim |
trimLeading | shared actual String trimLeading(Boolean trimming(Character element)) A string containing the characters of this string, after discarding the characters matching the given predicate function from the beginning of the string. A character is removed from the string if it matches the given predicate and every character occurring earlier in the string also matches the predicate. Refines List.trimLeading |
trimTrailing | shared actual String trimTrailing(Boolean trimming(Character element)) A string containing the characters of this string, after discarding the characters matching the given predicate function from the end of the string. A character is removed from the string if it matches the given predicate and every character occurring later in the string also matches the predicate. Refines List.trimTrailing |