dart:core
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:
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.
- Implemented by
Constructors
- List([int length ])
factory
- Creates a list of the given length. [...]
- List.filled(int length, E fill, { bool growable: false })
factory
- 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 })
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
inherited-getter, read / write, inherited
- Returns the first element. [...]
- last ↔ E
inherited-getter, read / write, inherited
- 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>
- 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 objects from
start
inclusive to end
exclusive. [...] - 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
index
th 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 [](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. - operator ==(dynamic other) → bool
inherited
- The equality operator. [...]
Static Methods
- castFrom<S, T>(List<S> source) → List<T>
- 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. [...]