E - the type of elements in this listpublic interface List<E> extends Collection<E>
Unlike sets, lists typically allow duplicate elements. More formally,
lists typically allow pairs of elements e1 and e2
such that e1.equals(e2), and they typically allow multiple
null elements if they allow null elements at all. It is not inconceivable
that someone might wish to implement a list that prohibits duplicates, by
throwing runtime exceptions when the user attempts to insert them, but we
expect this usage to be rare.
The List interface places additional stipulations, beyond those
specified in the Collection interface, on the contracts of the
iterator, add, remove, equals, and
hashCode methods. Declarations for other inherited methods are
also included here for convenience.
The List interface provides four methods for positional (indexed)
access to list elements. Lists (like Java arrays) are zero based. Note
that these operations may execute in time proportional to the index value
for some implementations (the LinkedList class, for
example). Thus, iterating over the elements in a list is typically
preferable to indexing through it if the caller does not know the
implementation.
The List interface provides a special iterator, called a
ListIterator, that allows element insertion and replacement, and
bidirectional access in addition to the normal operations that the
Iterator interface provides. A method is provided to obtain a
list iterator that starts at a specified position in the list.
The List interface provides two methods to search for a specified
object. From a performance standpoint, these methods should be used with
caution. In many implementations they will perform costly linear
searches.
The List interface provides two methods to efficiently insert and
remove multiple elements at an arbitrary point in the list.
Note: While it is permissible for lists to contain themselves as elements,
extreme caution is advised: the equals and hashCode
methods are no longer well defined on such a list.
Some list implementations have restrictions on the elements that
they may contain. For example, some implementations prohibit null elements,
and some have restrictions on the types of their elements. Attempting to
add an ineligible element throws an unchecked exception, typically
NullPointerException or ClassCastException. Attempting
to query the presence of an ineligible element may throw an exception,
or it may simply return false; some implementations will exhibit the former
behavior and some will exhibit the latter. More generally, attempting an
operation on an ineligible element whose completion would not result in
the insertion of an ineligible element into the list may throw an
exception or it may succeed, at the option of the implementation.
Such exceptions are marked as "optional" in the specification for this
interface.
The List.of() static factory methods
provide a convenient way to create immutable lists. The List
instances created by these methods have the following characteristics:
UnsupportedOperationException.
However, if the contained elements are themselves mutable,
this may cause the List's contents to appear to change.
null elements. Attempts to create them with
null elements result in NullPointerException.
==),
identity hash code, and synchronization) are unreliable and should be avoided.
This interface is a member of the Java Collections Framework.
Collection,
Set,
ArrayList,
LinkedList,
Vector,
Arrays.asList(Object[]),
Collections.nCopies(int, Object),
Collections.EMPTY_LIST,
AbstractList,
AbstractSequentialList| Modifier and Type | Method and Description |
|---|---|
boolean |
add(E e)
Appends the specified element to the end of this list (optional
operation).
|
void |
add(int index,
E element)
Inserts the specified element at the specified position in this list
(optional operation).
|
boolean |
addAll(Collection<? extends E> c)
Appends all of the elements in the specified collection to the end of
this list, in the order that they are returned by the specified
collection's iterator (optional operation).
|
boolean |
addAll(int index,
Collection<? extends E> c)
Inserts all of the elements in the specified collection into this
list at the specified position (optional operation).
|
void |
clear()
Removes all of the elements from this list (optional operation).
|
boolean |
contains(Object o)
Returns
true if this list contains the specified element. |
boolean |
containsAll(Collection<?> c)
Returns
true if this list contains all of the elements of the
specified collection. |
boolean |
equals(Object o)
Compares the specified object with this list for equality.
|
E |
get(int index)
Returns the element at the specified position in this list.
|
int |
hashCode()
Returns the hash code value for this list.
|
int |
indexOf(Object o)
Returns the index of the first occurrence of the specified element
in this list, or -1 if this list does not contain the element.
|
boolean |
isEmpty()
Returns
true if this list contains no elements. |
Iterator<E> |
iterator()
Returns an iterator over the elements in this list in proper sequence.
|
int |
lastIndexOf(Object o)
Returns the index of the last occurrence of the specified element
in this list, or -1 if this list does not contain the element.
|
ListIterator<E> |
listIterator()
Returns a list iterator over the elements in this list (in proper
sequence).
|
ListIterator<E> |
listIterator(int index)
Returns a list iterator over the elements in this list (in proper
sequence), starting at the specified position in the list.
|
static <E> List<E> |
of()
Returns an immutable list containing zero elements.
|
static <E> List<E> |
of(E... elements)
Returns an immutable list containing an arbitrary number of elements.
|
static <E> List<E> |
of(E e1)
Returns an immutable list containing one element.
|
static <E> List<E> |
of(E e1,
E e2)
Returns an immutable list containing two elements.
|
static <E> List<E> |
of(E e1,
E e2,
E e3)
Returns an immutable list containing three elements.
|
static <E> List<E> |
of(E e1,
E e2,
E e3,
E e4)
Returns an immutable list containing four elements.
|
static <E> List<E> |
of(E e1,
E e2,
E e3,
E e4,
E e5)
Returns an immutable list containing five elements.
|
static <E> List<E> |
of(E e1,
E e2,
E e3,
E e4,
E e5,
E e6)
Returns an immutable list containing six elements.
|
static <E> List<E> |
of(E e1,
E e2,
E e3,
E e4,
E e5,
E e6,
E e7)
Returns an immutable list containing seven elements.
|
static <E> List<E> |
of(E e1,
E e2,
E e3,
E e4,
E e5,
E e6,
E e7,
E e8)
Returns an immutable list containing eight elements.
|
static <E> List<E> |
of(E e1,
E e2,
E e3,
E e4,
E e5,
E e6,
E e7,
E e8,
E e9)
Returns an immutable list containing nine elements.
|
static <E> List<E> |
of(E e1,
E e2,
E e3,
E e4,
E e5,
E e6,
E e7,
E e8,
E e9,
E e10)
Returns an immutable list containing ten elements.
|
E |
remove(int index)
Removes the element at the specified position in this list (optional
operation).
|
boolean |
remove(Object o)
Removes the first occurrence of the specified element from this list,
if it is present (optional operation).
|
boolean |
removeAll(Collection<?> c)
Removes from this list all of its elements that are contained in the
specified collection (optional operation).
|
default void |
replaceAll(UnaryOperator<E> operator)
Replaces each element of this list with the result of applying the
operator to that element.
|
boolean |
retainAll(Collection<?> c)
Retains only the elements in this list that are contained in the
specified collection (optional operation).
|
E |
set(int index,
E element)
Replaces the element at the specified position in this list with the
specified element (optional operation).
|
int |
size()
Returns the number of elements in this list.
|
default void |
sort(Comparator<? super E> c)
Sorts this list according to the order induced by the specified
Comparator. |
default Spliterator<E> |
spliterator()
Creates a
Spliterator over the elements in this list. |
List<E> |
subList(int fromIndex,
int toIndex)
Returns a view of the portion of this list between the specified
fromIndex, inclusive, and toIndex, exclusive. |
Object[] |
toArray()
Returns an array containing all of the elements in this list in proper
sequence (from first to last element).
|
<T> T[] |
toArray(T[] a)
Returns an array containing all of the elements in this list in
proper sequence (from first to last element); the runtime type of
the returned array is that of the specified array.
|
parallelStream, removeIf, streamint size()
Integer.MAX_VALUE elements, returns
Integer.MAX_VALUE.size in interface Collection<E>boolean isEmpty()
true if this list contains no elements.isEmpty in interface Collection<E>true if this list contains no elementsboolean contains(Object o)
true if this list contains the specified element.
More formally, returns true if and only if this list contains
at least one element e such that
Objects.equals(o, e).contains in interface Collection<E>o - element whose presence in this list is to be testedtrue if this list contains the specified elementClassCastException - if the type of the specified element
is incompatible with this list
(optional)NullPointerException - if the specified element is null and this
list does not permit null elements
(optional)Iterator<E> iterator()
Object[] toArray()
The returned array will be "safe" in that no references to it are maintained by this list. (In other words, this method must allocate a new array even if this list is backed by an array). The caller is thus free to modify the returned array.
This method acts as bridge between array-based and collection-based APIs.
toArray in interface Collection<E>Arrays.asList(Object[])<T> T[] toArray(T[] a)
If the list fits in the specified array with room to spare (i.e.,
the array has more elements than the list), the element in the array
immediately following the end of the list is set to null.
(This is useful in determining the length of the list only if
the caller knows that the list does not contain any null elements.)
Like the toArray() method, this method acts as bridge between
array-based and collection-based APIs. Further, this method allows
precise control over the runtime type of the output array, and may,
under certain circumstances, be used to save allocation costs.
Suppose x is a list known to contain only strings.
The following code can be used to dump the list into a newly
allocated array of String:
String[] y = x.toArray(new String[0]);
toArray(new Object[0]) is identical in function to
toArray().toArray in interface Collection<E>T - the runtime type of the array to contain the collectiona - the array into which the elements of this list are to
be stored, if it is big enough; otherwise, a new array of the
same runtime type is allocated for this purpose.ArrayStoreException - if the runtime type of the specified array
is not a supertype of the runtime type of every element in
this listNullPointerException - if the specified array is nullboolean add(E e)
Lists that support this operation may place limitations on what elements may be added to this list. In particular, some lists will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. List classes should clearly specify in their documentation any restrictions on what elements may be added.
add in interface Collection<E>e - element to be appended to this listtrue (as specified by Collection.add(E))UnsupportedOperationException - if the add operation
is not supported by this listClassCastException - if the class of the specified element
prevents it from being added to this listNullPointerException - if the specified element is null and this
list does not permit null elementsIllegalArgumentException - if some property of this element
prevents it from being added to this listboolean remove(Object o)
i such that
Objects.equals(o, get(i))
(if such an element exists). Returns true if this list
contained the specified element (or equivalently, if this list changed
as a result of the call).remove in interface Collection<E>o - element to be removed from this list, if presenttrue if this list contained the specified elementClassCastException - if the type of the specified element
is incompatible with this list
(optional)NullPointerException - if the specified element is null and this
list does not permit null elements
(optional)UnsupportedOperationException - if the remove operation
is not supported by this listboolean containsAll(Collection<?> c)
true if this list contains all of the elements of the
specified collection.containsAll in interface Collection<E>c - collection to be checked for containment in this listtrue if this list contains all of the elements of the
specified collectionClassCastException - if the types of one or more elements
in the specified collection are incompatible with this
list
(optional)NullPointerException - if the specified collection contains one
or more null elements and this list does not permit null
elements
(optional),
or if the specified collection is nullcontains(Object)boolean addAll(Collection<? extends E> c)
addAll in interface Collection<E>c - collection containing elements to be added to this listtrue if this list changed as a result of the callUnsupportedOperationException - if the addAll operation
is not supported by this listClassCastException - if the class of an element of the specified
collection prevents it from being added to this listNullPointerException - if the specified collection contains one
or more null elements and this list does not permit null
elements, or if the specified collection is nullIllegalArgumentException - if some property of an element of the
specified collection prevents it from being added to this listadd(Object)boolean addAll(int index,
Collection<? extends E> c)
index - index at which to insert the first element from the
specified collectionc - collection containing elements to be added to this listtrue if this list changed as a result of the callUnsupportedOperationException - if the addAll operation
is not supported by this listClassCastException - if the class of an element of the specified
collection prevents it from being added to this listNullPointerException - if the specified collection contains one
or more null elements and this list does not permit null
elements, or if the specified collection is nullIllegalArgumentException - if some property of an element of the
specified collection prevents it from being added to this listIndexOutOfBoundsException - if the index is out of range
(index < 0 || index > size())boolean removeAll(Collection<?> c)
removeAll in interface Collection<E>c - collection containing elements to be removed from this listtrue if this list changed as a result of the callUnsupportedOperationException - if the removeAll operation
is not supported by this listClassCastException - if the class of an element of this list
is incompatible with the specified collection
(optional)NullPointerException - if this list contains a null element and the
specified collection does not permit null elements
(optional),
or if the specified collection is nullremove(Object),
contains(Object)boolean retainAll(Collection<?> c)
retainAll in interface Collection<E>c - collection containing elements to be retained in this listtrue if this list changed as a result of the callUnsupportedOperationException - if the retainAll operation
is not supported by this listClassCastException - if the class of an element of this list
is incompatible with the specified collection
(optional)NullPointerException - if this list contains a null element and the
specified collection does not permit null elements
(optional),
or if the specified collection is nullremove(Object),
contains(Object)default void replaceAll(UnaryOperator<E> operator)
list:
final ListIterator<E> li = list.listIterator();
while (li.hasNext()) {
li.set(operator.apply(li.next()));
}
set operation
then an UnsupportedOperationException will be thrown when
replacing the first element.operator - the operator to apply to each elementUnsupportedOperationException - if this list is unmodifiable.
Implementations may throw this exception if an element
cannot be replaced or if, in general, modification is not
supportedNullPointerException - if the specified operator is null or
if the operator result is a null value and this list does
not permit null elements
(optional)default void sort(Comparator<? super E> c)
Comparator.
All elements in this list must be mutually comparable using the
specified comparator (that is, c.compare(e1, e2) must not throw
a ClassCastException for any elements e1 and e2
in the list).
If the specified comparator is null then all elements in this
list must implement the Comparable interface and the elements'
natural ordering should be used.
This list must be modifiable, but need not be resizable.
The implementation takes equal advantage of ascending and descending order in its input array, and can take advantage of ascending and descending order in different parts of the same input array. It is well-suited to merging two or more sorted arrays: simply concatenate the arrays and sort the resulting array.
The implementation was adapted from Tim Peters's list sort for Python ( TimSort). It uses techniques from Peter McIlroy's "Optimistic Sorting and Information Theoretic Complexity", in Proceedings of the Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474, January 1993.
c - the Comparator used to compare list elements.
A null value indicates that the elements'
natural ordering should be usedClassCastException - if the list contains elements that are not
mutually comparable using the specified comparatorUnsupportedOperationException - if the list's list-iterator does
not support the set operationIllegalArgumentException - (optional)
if the comparator is found to violate the Comparator
contractvoid clear()
clear in interface Collection<E>UnsupportedOperationException - if the clear operation
is not supported by this listboolean equals(Object o)
true if and only if the specified object is also a list, both
lists have the same size, and all corresponding pairs of elements in
the two lists are equal. (Two elements e1 and
e2 are equal if Objects.equals(e1, e2).)
In other words, two lists are defined to be
equal if they contain the same elements in the same order. This
definition ensures that the equals method works properly across
different implementations of the List interface.equals in interface Collection<E>equals in class Objecto - the object to be compared for equality with this listtrue if the specified object is equal to this listObject.hashCode(),
HashMapint hashCode()
int hashCode = 1;
for (E e : list)
hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
list1.equals(list2) implies that
list1.hashCode()==list2.hashCode() for any two lists,
list1 and list2, as required by the general
contract of Object.hashCode().hashCode in interface Collection<E>hashCode in class ObjectObject.equals(Object),
equals(Object)E get(int index)
index - index of the element to returnIndexOutOfBoundsException - if the index is out of range
(index < 0 || index >= size())E set(int index, E element)
index - index of the element to replaceelement - element to be stored at the specified positionUnsupportedOperationException - if the set operation
is not supported by this listClassCastException - if the class of the specified element
prevents it from being added to this listNullPointerException - if the specified element is null and
this list does not permit null elementsIllegalArgumentException - if some property of the specified
element prevents it from being added to this listIndexOutOfBoundsException - if the index is out of range
(index < 0 || index >= size())void add(int index,
E element)
index - index at which the specified element is to be insertedelement - element to be insertedUnsupportedOperationException - if the add operation
is not supported by this listClassCastException - if the class of the specified element
prevents it from being added to this listNullPointerException - if the specified element is null and
this list does not permit null elementsIllegalArgumentException - if some property of the specified
element prevents it from being added to this listIndexOutOfBoundsException - if the index is out of range
(index < 0 || index > size())E remove(int index)
index - the index of the element to be removedUnsupportedOperationException - if the remove operation
is not supported by this listIndexOutOfBoundsException - if the index is out of range
(index < 0 || index >= size())int indexOf(Object o)
i such that
Objects.equals(o, get(i)),
or -1 if there is no such index.o - element to search forClassCastException - if the type of the specified element
is incompatible with this list
(optional)NullPointerException - if the specified element is null and this
list does not permit null elements
(optional)int lastIndexOf(Object o)
i such that
Objects.equals(o, get(i)),
or -1 if there is no such index.o - element to search forClassCastException - if the type of the specified element
is incompatible with this list
(optional)NullPointerException - if the specified element is null and this
list does not permit null elements
(optional)ListIterator<E> listIterator()
ListIterator<E> listIterator(int index)
next.
An initial call to previous would
return the element with the specified index minus one.index - index of the first element to be returned from the
list iterator (by a call to next)IndexOutOfBoundsException - if the index is out of range
(index < 0 || index > size())List<E> subList(int fromIndex, int toIndex)
fromIndex, inclusive, and toIndex, exclusive. (If
fromIndex and toIndex are equal, the returned list is
empty.) The returned list is backed by this list, so non-structural
changes in the returned list are reflected in this list, and vice-versa.
The returned list supports all of the optional list operations supported
by this list.This method eliminates the need for explicit range operations (of the sort that commonly exist for arrays). Any operation that expects a list can be used as a range operation by passing a subList view instead of a whole list. For example, the following idiom removes a range of elements from a list:
list.subList(from, to).clear();
indexOf and
lastIndexOf, and all of the algorithms in the
Collections class can be applied to a subList.The semantics of the list returned by this method become undefined if the backing list (i.e., this list) is structurally modified in any way other than via the returned list. (Structural modifications are those that change the size of this list, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results.)
fromIndex - low endpoint (inclusive) of the subListtoIndex - high endpoint (exclusive) of the subListIndexOutOfBoundsException - for an illegal endpoint index value
(fromIndex < 0 || toIndex > size ||
fromIndex > toIndex)default Spliterator<E> spliterator()
Spliterator over the elements in this list.
The Spliterator reports Spliterator.SIZED and
Spliterator.ORDERED. Implementations should document the
reporting of additional characteristic values.
spliterator in interface Collection<E>spliterator in interface Iterable<E>Iterator. The spliterator inherits the
fail-fast properties of the list's iterator.Spliterator additionally reports
Spliterator.SUBSIZED.Spliterator over the elements in this liststatic <E> List<E> of()
E - the List's element typeListstatic <E> List<E> of(E e1)
E - the List's element typee1 - the single elementList containing the specified elementNullPointerException - if the element is nullstatic <E> List<E> of(E e1, E e2)
E - the List's element typee1 - the first elemente2 - the second elementList containing the specified elementsNullPointerException - if an element is nullstatic <E> List<E> of(E e1, E e2, E e3)
E - the List's element typee1 - the first elemente2 - the second elemente3 - the third elementList containing the specified elementsNullPointerException - if an element is nullstatic <E> List<E> of(E e1, E e2, E e3, E e4)
E - the List's element typee1 - the first elemente2 - the second elemente3 - the third elemente4 - the fourth elementList containing the specified elementsNullPointerException - if an element is nullstatic <E> List<E> of(E e1, E e2, E e3, E e4, E e5)
E - the List's element typee1 - the first elemente2 - the second elemente3 - the third elemente4 - the fourth elemente5 - the fifth elementList containing the specified elementsNullPointerException - if an element is nullstatic <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6)
E - the List's element typee1 - the first elemente2 - the second elemente3 - the third elemente4 - the fourth elemente5 - the fifth elemente6 - the sixth elementList containing the specified elementsNullPointerException - if an element is nullstatic <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7)
E - the List's element typee1 - the first elemente2 - the second elemente3 - the third elemente4 - the fourth elemente5 - the fifth elemente6 - the sixth elemente7 - the seventh elementList containing the specified elementsNullPointerException - if an element is nullstatic <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8)
E - the List's element typee1 - the first elemente2 - the second elemente3 - the third elemente4 - the fourth elemente5 - the fifth elemente6 - the sixth elemente7 - the seventh elemente8 - the eighth elementList containing the specified elementsNullPointerException - if an element is nullstatic <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9)
E - the List's element typee1 - the first elemente2 - the second elemente3 - the third elemente4 - the fourth elemente5 - the fifth elemente6 - the sixth elemente7 - the seventh elemente8 - the eighth elemente9 - the ninth elementList containing the specified elementsNullPointerException - if an element is nullstatic <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9, E e10)
E - the List's element typee1 - the first elemente2 - the second elemente3 - the third elemente4 - the fourth elemente5 - the fifth elemente6 - the sixth elemente7 - the seventh elemente8 - the eighth elemente9 - the ninth elemente10 - the tenth elementList containing the specified elementsNullPointerException - if an element is null@SafeVarargs static <E> List<E> of(E... elements)
String[] array = ... ;
List<String[]> list = List.<String[]>of(array);
List.of(E) method
to be invoked instead.E - the List's element typeelements - the elements to be contained in the listList containing the specified elementsNullPointerException - if an element is null or if the array is null Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2016, Oracle and/or its affiliates. All rights reserved.
DRAFT 9-internal+0-2016-01-26-133437.ivan.openjdk9onspinwait