description

# List<E> class Null safety

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.

    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.

Implementers
  - DomRectList
  - DomStringList
  - FileList
  - Float32List
  - Float32x4List
  - Float64List
  - Float64x2List
  - HtmlCollection
  - ImmutableListMixin
  - Int16List
  - Int32List
  - Int32x4List
  - Int64List
  - Int8List
  - LengthList
  - ListMixin
  - MimeTypeArray
  - NodeList
  - NumberList
  - PluginArray
  - SourceBufferList
  - SpeechGrammarList
  - SqlResultSetRowList
  - StringList
  - TextTrackCueList
  - TextTrackList
  - TouchList
  - TransformList
  - Uint16List
  - Uint32List
  - Uint64List
  - Uint8ClampedList
  - Uint8List

## Constructors

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

## Properties

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

## 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
  Checks whether any element of this iterable satisfies `test`. [...]
  inherited
asMap() → Map<int, E>
  Returns an unmodifiable Map view of `this`. [...]
cast<R>() → List<R>
  Returns a view of this list as a list of `R` instances. [...]
  override
clear() → void
  Removes all objects from this list; the length of the list becomes zero. [...]
contains(Object? element) → bool
  Returns true if the collection contains an element equal to `element`. [...]
  inherited
elementAt(int index) → E
  Returns the `index`th element. [...]
  inherited
every(bool test(E element)) → bool
  Checks whether every element of this iterable satisfies `test`. [...]
  inherited
expand<T>(Iterable<T> f(E element)) → Iterable<T>
  Expands each element of this Iterable into zero or more elements. [...]
  inherited
fillRange(int start, int end, [E? fillValue]) → void
  Sets the objects in the range `start` inclusive to `end` exclusive to the given `fillValue`. [...]
firstWhere(bool test(E element), {E orElse()}) → E
  Returns the first element that satisfies the given predicate `test`. [...]
  inherited
fold<T>(T initialValue, T combine(T previousValue, E element)) → T
  Reduces a collection to a single value by iteratively combining each element of the collection with an existing value [...]
  inherited
followedBy(Iterable<E> other) → Iterable<E>
  Returns the lazy concatentation of this iterable and `other`. [...]
  inherited
forEach(void f(E element)) → void
  Applies the function `f` to each element of this collection in iteration order.
  inherited
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. [...]
join([String separator = ""]) → String
  Converts each element to a String and concatenates the strings. [...]
  inherited
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`. [...]
lastWhere(bool test(E element), {E orElse()}) → E
  Returns the last element that satisfies the given predicate `test`. [...]
  inherited
map<T>(T f(E e)) → Iterable<T>
  Returns a new lazy Iterable with elements that are created by calling `f` on each element of this `Iterable` in iteration order. [...]
  inherited
noSuchMethod(Invocation invocation) → dynamic
  Invoked when a non-existent method or property is accessed. [...]
  inherited
reduce(E combine(E value, E element)) → E
  Reduces a collection to a single value by iteratively combining elements of the collection using the provided function. [...]
  inherited
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.
singleWhere(bool test(E element), {E orElse()}) → E
  Returns the single element that satisfies `test`. [...]
  inherited
skip(int count) → Iterable<E>
  Returns an Iterable that provides all but the first `count` elements. [...]
  inherited
skipWhile(bool test(E value)) → Iterable<E>
  Returns an `Iterable` that skips leading elements while `test` is satisfied. [...]
  inherited
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>
  Returns a lazy iterable of the `count` first elements of this iterable. [...]
  inherited
takeWhile(bool test(E value)) → Iterable<E>
  Returns a lazy iterable of the leading elements satisfying `test`. [...]
  inherited
toList({bool growable: true}) → List<E>
  Creates a List containing the elements of this Iterable. [...]
  inherited
toSet() → Set<E>
  Creates a Set containing the same elements as this iterable. [...]
  inherited
toString() → String
  Returns a string representation of this object.
  inherited
where(bool test(E element)) → Iterable<E>
  Returns a new lazy Iterable with all elements that satisfy the predicate `test`. [...]
  inherited
whereType<T>() → Iterable<T>
  Returns a new lazy Iterable with all elements that have type `T`. [...]
  inherited

## Operators

operator +(List<E> other) → List<E>
  Returns the concatenation of this list and `other`. [...]
operator ==(Object other) → bool
  Whether this list is equal to `other`. [...]
  override
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>
  Adapts `source` to be a `List<T>`. [...]
  override
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. [...]