W3cubDocs

/Dart 2

List<E> class

An indexable collection of objects with a length.

Subclasses of this class implement different kinds of lists. The most common kinds of lists are:

Fixed-length list. An error occurs when attempting to use operations that can change the length of the list.
Growable list. Full implementation of the API defined in this class.

The default growable list, as returned by new List() or [], keeps an internal buffer, and grows that buffer when necessary. This guarantees that a sequence of add operations will each execute in amortized constant time. Setting the length directly may take time proportional to the new length, and may change the internal capacity so that a following add operation will need to immediately increase the buffer capacity. Other list implementations may have different performance behavior.

The following code illustrates that some List implementations support only a subset of the API.

List<int> fixedLengthList = new List(5);
fixedLengthList.length = 0;  // Error
fixedLengthList.add(499);    // Error
fixedLengthList[0] = 87;
List<int> growableList = [1, 2];
growableList.length = 0;
growableList.add(499);
growableList[0] = 87;

Lists are Iterable. Iteration occurs over values in index order. Changing the values does not affect iteration, but changing the valid indices—that is, changing the list's length—between iteration steps causes a ConcurrentModificationError. This means that only growable lists can throw ConcurrentModificationError. If the length changes temporarily and is restored before continuing the iteration, the iterator does not detect it.

It is generally not allowed to modify the list's length (adding or removing elements) while an operation on the list is being performed, for example during a call to forEach or sort. Changing the list's length while it is being iterated, either by iterating it directly or through iterating an Iterable that is backed by the list, will break the iteration.

Constructors

List([int length ]) factory: Creates a list of the given length. [...]
List.filled(int length, E fill, { bool growable: false }) factory: Creates a list of the given length with fill at each position. [...]
List.from(Iterable elements, { bool growable: true }) factory: Creates a list containing all elements. [...]
List.generate(int length, E generator(int index), { bool growable: true }) factory: Generates a list of values. [...]
List.of(Iterable<E> elements, { bool growable: true }) factory: Creates a list from elements. [...]
List.unmodifiable(Iterable elements) factory: Creates an unmodifiable list containing all elements. [...]

Properties

first ↔ E read / write, inherited-getter: Returns the first element. [...]
last ↔ E read / write, inherited-getter: Returns the last element. [...]
length ↔ int read / write: Returns the number of objects in this list. [...]
reversed → Iterable<E> read-only: Returns an Iterable of the objects in this list in reverse order.
hashCode → int read-only, inherited: The hash code for this object. [...]
isEmpty → bool read-only, inherited: Returns true if there are no elements in this collection. [...]
isNotEmpty → bool read-only, inherited: Returns true if there is at least one element in this collection. [...]
iterator → Iterator<E> read-only, inherited: Returns a new Iterator that allows iterating the elements of this Iterable. [...]
runtimeType → Type read-only, inherited: A representation of the runtime type of the object.
single → E read-only, inherited: Checks that this iterable has only one element, and returns that element. [...]

Methods

add(E value) → void: Adds value to the end of this list, extending the length by one. [...]
addAll(Iterable<E> iterable) → void: Appends all objects of iterable to the end of this list. [...]
asMap() → Map<int, E>: Returns an unmodifiable Map view of this. [...]
cast<R>() → List<R> override: Returns a view of this list as a list of R instances. [...]
clear() → void: Removes all objects from this list; the length of the list becomes zero. [...]
fillRange(int start, int end, [ E fillValue ]) → void: Sets the objects in the range start inclusive to end exclusive to the given fillValue. [...]
getRange(int start, int end) → Iterable<E>: Returns an Iterable that iterates over the objects in the range start inclusive to end exclusive. [...]
indexOf(E element, [ int start = 0 ]) → int: Returns the first index of element in this list. [...]
indexWhere(bool test(E element), [ int start = 0 ]) → int: Returns the first index in the list that satisfies the provided test. [...]
insert(int index, E element) → void: Inserts the object at position index in this list. [...]
insertAll(int index, Iterable<E> iterable) → void: Inserts all objects of iterable at position index in this list. [...]
lastIndexOf(E element, [ int start ]) → int: Returns the last index of element in this list. [...]
lastIndexWhere(bool test(E element), [ int start ]) → int: Returns the last index in the list that satisfies the provided test. [...]
remove(Object value) → bool: Removes the first occurrence of value from this list. [...]
removeAt(int index) → E: Removes the object at position index from this list. [...]
removeLast() → E: Pops and returns the last object in this list. [...]
removeRange(int start, int end) → void: Removes the objects in the range start inclusive to end exclusive. [...]
removeWhere(bool test(E element)) → void: Removes all objects from this list that satisfy test. [...]
replaceRange(int start, int end, Iterable<E> replacement) → void: Removes the objects in the range start inclusive to end exclusive and inserts the contents of replacement in its place. [...]
retainWhere(bool test(E element)) → void: Removes all objects from this list that fail to satisfy test. [...]
setAll(int index, Iterable<E> iterable) → void: Overwrites objects of this with the objects of iterable, starting at position index in this list. [...]
setRange(int start, int end, Iterable<E> iterable, [ int skipCount = 0 ]) → void: Copies the objects of iterable, skipping skipCount objects first, into the range start, inclusive, to end, exclusive, of the list. [...]
shuffle([Random random ]) → void: Shuffles the elements of this list randomly.
sort([int compare(E a, E b) ]) → void: Sorts this list according to the order specified by the compare function. [...]
sublist(int start, [ int end ]) → List<E>: Returns a new list containing the elements between start and end. [...]
any(bool test(E element)) → bool inherited: Checks whether any element of this iterable satisfies test. [...]
contains(Object element) → bool inherited: Returns true if the collection contains an element equal to element. [...]
elementAt(int index) → E inherited: Returns the indexth element. [...]
every(bool test(E element)) → bool inherited: Checks whether every element of this iterable satisfies test. [...]
expand<T>(Iterable<T> f(E element)) → Iterable<T> inherited: Expands each element of this Iterable into zero or more elements. [...]
firstWhere(bool test(E element), { E orElse() }) → E inherited: Returns the first element that satisfies the given predicate test. [...]
fold<T>(T initialValue, T combine(T previousValue, E element)) → T inherited: Reduces a collection to a single value by iteratively combining each element of the collection with an existing value [...]
followedBy(Iterable<E> other) → Iterable<E> inherited: Returns the lazy concatentation of this iterable and other. [...]
forEach(void f(E element)) → void inherited: Applies the function f to each element of this collection in iteration order.
join([String separator = "" ]) → String inherited: Converts each element to a String and concatenates the strings. [...]
lastWhere(bool test(E element), { E orElse() }) → E inherited: Returns the last element that satisfies the given predicate test. [...]
map<T>(T f(E e)) → Iterable<T> inherited: Returns a new lazy Iterable with elements that are created by calling f on each element of this Iterable in iteration order. [...]
noSuchMethod(Invocation invocation) → dynamic inherited: Invoked when a non-existent method or property is accessed. [...]
reduce(E combine(E value, E element)) → E inherited: Reduces a collection to a single value by iteratively combining elements of the collection using the provided function. [...]
singleWhere(bool test(E element), { E orElse() }) → E inherited: Returns the single element that satisfies test. [...]
skip(int count) → Iterable<E> inherited: Returns an Iterable that provides all but the first count elements. [...]
skipWhile(bool test(E value)) → Iterable<E> inherited: Returns an Iterable that skips leading elements while test is satisfied. [...]
take(int count) → Iterable<E> inherited: Returns a lazy iterable of the count first elements of this iterable. [...]
takeWhile(bool test(E value)) → Iterable<E> inherited: Returns a lazy iterable of the leading elements satisfying test. [...]
toList({bool growable: true }) → List<E> inherited: Creates a List containing the elements of this Iterable. [...]
toSet() → Set<E> inherited: Creates a Set containing the same elements as this iterable. [...]
toString() → String inherited: Returns a string representation of this object.
where(bool test(E element)) → Iterable<E> inherited: Returns a new lazy Iterable with all elements that satisfy the predicate test. [...]
whereType<T>() → Iterable<T> inherited: Returns a new lazy Iterable with all elements that have type T. [...]

Operators

operator +(List<E> other) → List<E>: Returns the concatenation of this list and other. [...]
operator ==(Object other) → bool override: Whether this list is equal to other. [...]
operator [](int index) → E: Returns the object at the given index in the list or throws a RangeError if index is out of bounds.
operator []=(int index, E value) → void: Sets the value at the given index in the list to value or throws a RangeError if index is out of bounds.

Static Methods

castFrom<S, T>(List<S> source) → List<T> override: Adapts source to be a List<T>. [...]
copyRange<T>(List<T> target, int at, List<T> source, [ int start, int end ]) → void: Copy a range of one list into another list. [...]
writeIterable<T>(List<T> target, int at, Iterable<T> source) → void: Write the elements of an iterable into a list. [...]

© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dart.dev/stable/2.5.0/dart-core/List-class.html