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 created by [], 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.

var fixedLengthList = List<int>.filled(5, 0);
fixedLengthList.length = 0;  // Error
fixedLengthList.add(499);    // Error
fixedLengthList[0] = 87;
var 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 might 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.

Implementers

Constructors

List([int? length]) factory: Creates a list of the given length. [...]
List.empty({bool growable = false}) factory: Creates a new empty list. [...]
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. [...]
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. [...]
last ↔ E read / write, inherited-getter: Returns the last element. [...]
length ↔ int read / write: The number of objects in this list. [...]
reversed → Iterable<E> read-only: An Iterable of the objects in this list in reverse order.
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. [...]
any(bool test(E element)) → bool inherited: Checks whether any element of this iterable satisfies test. [...]
asMap() → Map<int, E>: An unmodifiable Map view of this list. [...]
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. [...]
contains(Object? element) → bool inherited: Whether 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. [...]
fillRange(int start, int end, [E? fillValue]) → void: Overwrites a range of elements with fillValue. [...]
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 concatenation 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.
getRange(int start, int end) → Iterable<E>: Creates an Iterable that iterates over a range of elements. [...]
indexOf(E element, [int start = 0]) → int: The first index of element in this list. [...]
indexWhere(bool test(E element), [int start = 0]) → int: The first index in the list that satisfies the provided test. [...]
insert(int index, E element) → void: Inserts element at position index in this list. [...]
insertAll(int index, Iterable<E> iterable) → void: Inserts all objects of iterable at position index in this list. [...]
join([String separator = ""]) → String inherited: Converts each element to a String and concatenates the strings. [...]
lastIndexOf(E element, [int? start]) → int: The last index of element in this list. [...]
lastIndexWhere(bool test(E element), [int? start]) → int: The last index in the list that satisfies the provided test. [...]
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. [...]
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: Removes and returns the last object in this list. [...]
removeRange(int start, int end) → void: Removes a range of elements from the list. [...]
removeWhere(bool test(E element)) → void: Removes all objects from this list that satisfy test. [...]
replaceRange(int start, int end, Iterable<E> replacement) → void: Replaces a range of elements with the elements of replacement. [...]
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 elements with the objects of iterable. [...]
setRange(int start, int end, Iterable<E> iterable, [int skipCount = 0]) → void: Writes some elements of iterable into a range of this list. [...]
shuffle([Random? random]) → void: Shuffles the elements of this list randomly.
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. [...]
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. [...]
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: 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: The object at the given index in the list. [...]
operator []=(int index, E value) → void: Sets the value at the given index in the list to value. [...]

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/2.13.0/dart-core/List-class.html