class
List<E>

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.

Implements
Implemented by

Properties

int length
read / write
Returns the number of objects in this list.
Iterable<E> reversed
read-only
Returns an [Iterable] of the objects in this list in reverse order.
bool isEmpty
read-only , inherited
Returns true if there are no elements in this collection.
Iterator<E> iterator
read-only , inherited
Returns a new Iterator that allows iterating the elements of this Iterable.
bool isNotEmpty
read-only , inherited
Returns true if there is at least one element in this collection.
E first
read-only , inherited
Returns the first element.
E last
read-only , inherited
Returns the last element.
E single
read-only , inherited
Checks that this iterable has only one element, and returns that element.

Constructors

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

Operators

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.

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.
sort([int compare(E a, E b)]) → void
Sorts this list according to the order specified by the compare function.
shuffle([Random random]) → void
Shuffles the elements of this list randomly.
indexOf(E element, [int start = 0]) → int
Returns the first index of element in this list.
lastIndexOf(E element, [int start]) → int
Returns the last index of element in this list.
clear() → void
Removes all objects from this list; the length of the list becomes zero.
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.
setAll(int index, Iterable<E> iterable) → void
Overwrites objects of this with the objects of iterable, starting at position index in this list.
remove(Object value) → bool
Removes the first occurence 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.
removeWhere(bool test(E element)) → void
Removes all objects from this list that satisfy test.
retainWhere(bool test(E element)) → void
Removes all objects from this list that fail to satisfy test.
sublist(int start, [int end]) → List<E>
Returns a new list containing the objects from start inclusive to end exclusive.
getRange(int start, int end) → Iterable<E>
Returns an Iterable that iterates over the objects in the range start inclusive to end exclusive.
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.
removeRange(int start, int end) → void
Removes the objects in the range start inclusive to end exclusive.
fillRange(int start, int end, [E fillValue]) → void
Sets the objects in the range start inclusive to end exclusive to the given fillValue.
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.
asMap() → Map<int,E>
Returns an unmodifiable Map view of this.
take(int n) → Iterable<E>
inherited
Returns a lazy iterable of the count first elements of this iterable.
map(dynamic f(E element)) → Iterable
inherited
Returns a new lazy Iterable with elements that are created by calling f on each element of this Iterable in iteration order.
takeWhile(bool test(E value)) → Iterable<E>
inherited
Returns a lazy iterable of the leading elements satisfying test.
fold(initialValue, dynamic combine(previousValue, E element)) → dynamic
inherited
Reduces a collection to a single value by iteratively combining each element of the collection with an existing value
toSet() → Set<E>
inherited
Creates a Set containing the same elements as this iterable.
firstWhere(bool test(E element), {E orElse()}) → E
inherited
Returns the first element that satisfies the given predicate test.
forEach(void f(E element)) → void
inherited
Applies the function f to each element of this collection in iteration order.
skipWhile(bool test(E value)) → Iterable<E>
inherited
Returns an Iterable that skips leading elements while test is satisfied.
join([String separator = ""]) → String
inherited
Converts each element to a String and concatenates the strings.
contains(Object element) → bool
inherited
Returns true if the collection contains an element equal to element.
lastWhere(bool test(E element), {E orElse()}) → E
inherited
Returns the last element that satisfies the given predicate test.
singleWhere(bool test(E element)) → E
inherited
Returns the single element that satisfies test.
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.
every(bool f(E element)) → bool
inherited
Checks whether every element of this iterable satisfies test.
any(bool f(E element)) → bool
inherited
Checks whether any element of this iterable satisfies test.
toList({bool growable: true}) → List<E>
inherited
Creates a List containing the elements of this Iterable.
where(bool f(E element)) → Iterable<E>
inherited
Returns a new lazy Iterable with all elements that satisfy the predicate test.
skip(int n) → Iterable<E>
inherited
Returns an Iterable that provides all but the first count elements.
expand(Iterable f(E element)) → Iterable
inherited
Expands each element of this Iterableinto zero or more elements.
elementAt(int index) → E
inherited
Returns the indexth element.