Interface List<E>
- Type Parameters:
E
- the type of elements in this list
- All Superinterfaces:
Collection<E>
,Iterable<E>
,SequencedCollection<E>
- All Known Subinterfaces:
ClassPrinter.ListNode
- All Known Implementing Classes:
AbstractList
,AbstractSequentialList
,ArrayList
,AttributeList
,CopyOnWriteArrayList
,LinkedList
,RoleList
,RoleUnresolvedList
,Stack
,Vector
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.
Unmodifiable Lists
The List.of
and
List.copyOf
static factory methods
provide a convenient way to create unmodifiable lists. The List
instances created by these methods have the following characteristics:
- They are unmodifiable. Elements cannot
be added, removed, or replaced. Calling any mutator method on the List
will always cause
UnsupportedOperationException
to be thrown. However, if the contained elements are themselves mutable, this may cause the List's contents to appear to change. - They disallow
null
elements. Attempts to create them withnull
elements result inNullPointerException
. - They are serializable if all elements are serializable.
- The order of elements in the list is the same as the order of the provided arguments, or of the elements in the provided array.
- The lists and their
subList
views implement theRandomAccess
interface. - They are value-based. Programmers should treat instances that are equal as interchangeable and should not use them for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail. Callers should make no assumptions about the identity of the returned instances. Factories are free to create new instances or reuse existing ones.
- They are serialized as specified on the Serialized Form page.
This interface is a member of the Java Collections Framework.
- Since:
- 1.2
- See Also:
-
Method Summary
Modifier and TypeMethodDescriptionvoid
Inserts the specified element at the specified position in this list (optional operation).boolean
Appends the specified element to the end of this list (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).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).default void
Adds an element as the first element of this collection (optional operation).default void
Adds an element as the last element of this collection (optional operation).void
clear()
Removes all of the elements from this list (optional operation).boolean
Returnstrue
if this list contains the specified element.boolean
containsAll
(Collection<?> c) Returnstrue
if this list contains all of the elements of the specified collection.static <E> List
<E> copyOf
(Collection<? extends E> coll) Returns an unmodifiable List containing the elements of the given Collection, in its iteration order.boolean
Compares the specified object with this list for equality.get
(int index) Returns the element at the specified position in this list.default E
getFirst()
Gets the first element of this collection.default E
getLast()
Gets the last element of this collection.int
hashCode()
Returns the hash code value for this list.int
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()
Returnstrue
if this list contains no elements.iterator()
Returns an iterator over the elements in this list in proper sequence.int
Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.Returns a list iterator over the elements in this list (in proper sequence).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 unmodifiable list containing zero elements.static <E> List
<E> of
(E e1) Returns an unmodifiable list containing one element.static <E> List
<E> of
(E... elements) Returns an unmodifiable list containing an arbitrary number of elements.static <E> List
<E> of
(E e1, E e2) Returns an unmodifiable list containing two elements.static <E> List
<E> of
(E e1, E e2, E e3) Returns an unmodifiable list containing three elements.static <E> List
<E> of
(E e1, E e2, E e3, E e4) Returns an unmodifiable list containing four elements.static <E> List
<E> of
(E e1, E e2, E e3, E e4, E e5) Returns an unmodifiable list containing five elements.static <E> List
<E> of
(E e1, E e2, E e3, E e4, E e5, E e6) Returns an unmodifiable 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 unmodifiable 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 unmodifiable 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 unmodifiable 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 unmodifiable list containing ten elements.remove
(int index) Removes the element at the specified position in this list (optional operation).boolean
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 E
Removes and returns the first element of this collection (optional operation).default E
Removes and returns the last element of this 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 (optional operation).boolean
retainAll
(Collection<?> c) Retains only the elements in this list that are contained in the specified collection (optional operation).reversed()
Returns a reverse-ordered view of this collection.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 specifiedComparator
(optional operation).default Spliterator
<E> Creates aSpliterator
over the elements in this list.subList
(int fromIndex, int toIndex) Returns a view of the portion of this list between the specifiedfromIndex
, inclusive, andtoIndex
, 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.Methods inherited from interface java.util.Collection
parallelStream, removeIf, stream, toArray
-
Method Details
-
size
int size()Returns the number of elements in this list. If this list contains more thanInteger.MAX_VALUE
elements, returnsInteger.MAX_VALUE
.- Specified by:
size
in interfaceCollection<E>
- Returns:
- the number of elements in this list
-
isEmpty
boolean isEmpty()Returnstrue
if this list contains no elements.- Specified by:
isEmpty
in interfaceCollection<E>
- Returns:
true
if this list contains no elements
-
contains
Returnstrue
if this list contains the specified element. More formally, returnstrue
if and only if this list contains at least one elemente
such thatObjects.equals(o, e)
.- Specified by:
contains
in interfaceCollection<E>
- Parameters:
o
- element whose presence in this list is to be tested- Returns:
true
if this list contains the specified element- Throws:
ClassCastException
- 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
-
toArray
Object[] toArray()Returns an array containing all of the elements in this list in proper sequence (from first to last element).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.
- Specified by:
toArray
in interfaceCollection<E>
- Returns:
- an array containing all of the elements in this list in proper sequence
- See Also:
-
toArray
<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. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.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 ofString
:
Note thatString[] y = x.toArray(new String[0]);
toArray(new Object[0])
is identical in function totoArray()
.- Specified by:
toArray
in interfaceCollection<E>
- Type Parameters:
T
- the component type of the array to contain the collection- Parameters:
a
- 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.- Returns:
- an array containing the elements of this list
- Throws:
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 null
-
add
Appends the specified element to the end of this list (optional operation).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.
- Specified by:
add
in interfaceCollection<E>
- Parameters:
e
- element to be appended to this list- Returns:
true
(as specified byCollection.add(E)
)- Throws:
UnsupportedOperationException
- if theadd
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 list
-
remove
Removes the first occurrence of the specified element from this list, if it is present (optional operation). If this list does not contain the element, it is unchanged. More formally, removes the element with the lowest indexi
such thatObjects.equals(o, get(i))
(if such an element exists). Returnstrue
if this list contained the specified element (or equivalently, if this list changed as a result of the call).- Specified by:
remove
in interfaceCollection<E>
- Parameters:
o
- element to be removed from this list, if present- Returns:
true
if this list contained the specified element- Throws:
ClassCastException
- 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 theremove
operation is not supported by this list
-
containsAll
Returnstrue
if this list contains all of the elements of the specified collection.- Specified by:
containsAll
in interfaceCollection<E>
- Parameters:
c
- collection to be checked for containment in this list- Returns:
true
if this list contains all of the elements of the specified collection- Throws:
ClassCastException
- 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 null- See Also:
-
addAll
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). The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)- Specified by:
addAll
in interfaceCollection<E>
- Parameters:
c
- collection containing elements to be added to this list- Returns:
true
if this list changed as a result of the call- Throws:
UnsupportedOperationException
- if theaddAll
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 list- See Also:
-
addAll
Inserts all of the elements in the specified collection into this list at the specified position (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in this list in the order that they are returned by the specified collection's iterator. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)- Parameters:
index
- index at which to insert the first element from the specified collectionc
- collection containing elements to be added to this list- Returns:
true
if this list changed as a result of the call- Throws:
UnsupportedOperationException
- if theaddAll
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()
)
-
removeAll
Removes from this list all of its elements that are contained in the specified collection (optional operation).- Specified by:
removeAll
in interfaceCollection<E>
- Parameters:
c
- collection containing elements to be removed from this list- Returns:
true
if this list changed as a result of the call- Throws:
UnsupportedOperationException
- if theremoveAll
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 null- See Also:
-
retainAll
Retains only the elements in this list that are contained in the specified collection (optional operation). In other words, removes from this list all of its elements that are not contained in the specified collection.- Specified by:
retainAll
in interfaceCollection<E>
- Parameters:
c
- collection containing elements to be retained in this list- Returns:
true
if this list changed as a result of the call- Throws:
UnsupportedOperationException
- if theretainAll
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 null- See Also:
-
replaceAll
Replaces each element of this list with the result of applying the operator to that element (optional operation). Errors or runtime exceptions thrown by the operator are relayed to the caller.- Implementation Requirements:
- The default implementation is equivalent to, for this
list
:
If the list's list-iterator does not support thefinal ListIterator<E> li = list.listIterator(); while (li.hasNext()) { li.set(operator.apply(li.next())); }
set
operation then anUnsupportedOperationException
will be thrown when replacing the first element. - Parameters:
operator
- the operator to apply to each element- Throws:
UnsupportedOperationException
- if thereplaceAll
operation is not supported by this listNullPointerException
- if the specified operator is null or if the operator result is a null value and this list does not permit null elements (optional)- Since:
- 1.8
-
sort
Sorts this list according to the order induced by the specifiedComparator
(optional operation). The sort is stable: this method must not reorder equal elements.All elements in this list must be mutually comparable using the specified comparator (that is,
c.compare(e1, e2)
must not throw aClassCastException
for any elementse1
ande2
in the list).If the specified comparator is
null
then all elements in this list must implement theComparable
interface and the elements' natural ordering should be used.This list must be modifiable, but need not be resizable.
- Implementation Requirements:
- The default implementation obtains an array containing all elements in this list, sorts the array, and iterates over this list resetting each element from the corresponding position in the array. (This avoids the n2 log(n) performance that would result from attempting to sort a linked list in place.)
- Implementation Note:
- This implementation is a stable, adaptive, iterative mergesort that
requires far fewer than n lg(n) comparisons when the input array is
partially sorted, while offering the performance of a traditional
mergesort when the input array is randomly ordered. If the input array
is nearly sorted, the implementation requires approximately n
comparisons. Temporary storage requirements vary from a small constant
for nearly sorted input arrays to n/2 object references for randomly
ordered input arrays.
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.
- Parameters:
c
- theComparator
used to compare list elements. Anull
value indicates that the elements' natural ordering should be used- Throws:
ClassCastException
- if the list contains elements that are not mutually comparable using the specified comparatorUnsupportedOperationException
- if thesort
operation is not supported by this listIllegalArgumentException
- (optional) if the comparator is found to violate theComparator
contract- Since:
- 1.8
-
clear
void clear()Removes all of the elements from this list (optional operation). The list will be empty after this call returns.- Specified by:
clear
in interfaceCollection<E>
- Throws:
UnsupportedOperationException
- if theclear
operation is not supported by this list
-
equals
Compares the specified object with this list for equality. Returnstrue
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 elementse1
ande2
are equal ifObjects.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 theList
interface.- Specified by:
equals
in interfaceCollection<E>
- Overrides:
equals
in classObject
- Parameters:
o
- the object to be compared for equality with this list- Returns:
true
if the specified object is equal to this list- See Also:
-
hashCode
int hashCode()Returns the hash code value for this list. The hash code of a list is defined to be the result of the following calculation:
This ensures thatint hashCode = 1; for (E e : list) hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
list1.equals(list2)
implies thatlist1.hashCode()==list2.hashCode()
for any two lists,list1
andlist2
, as required by the general contract ofObject.hashCode()
.- Specified by:
hashCode
in interfaceCollection<E>
- Overrides:
hashCode
in classObject
- Returns:
- the hash code value for this list
- See Also:
-
get
Returns the element at the specified position in this list.- Parameters:
index
- index of the element to return- Returns:
- the element at the specified position in this list
- Throws:
IndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)
-
set
Replaces the element at the specified position in this list with the specified element (optional operation).- Parameters:
index
- index of the element to replaceelement
- element to be stored at the specified position- Returns:
- the element previously at the specified position
- Throws:
UnsupportedOperationException
- if theset
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()
)
-
add
Inserts the specified element at the specified position in this list (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).- Parameters:
index
- index at which the specified element is to be insertedelement
- element to be inserted- Throws:
UnsupportedOperationException
- if theadd
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()
)
-
remove
Removes the element at the specified position in this list (optional operation). Shifts any subsequent elements to the left (subtracts one from their indices). Returns the element that was removed from the list.- Parameters:
index
- the index of the element to be removed- Returns:
- the element previously at the specified position
- Throws:
UnsupportedOperationException
- if theremove
operation is not supported by this listIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)
-
indexOf
Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the lowest indexi
such thatObjects.equals(o, get(i))
, or -1 if there is no such index.- Parameters:
o
- element to search for- Returns:
- the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element
- Throws:
ClassCastException
- 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)
-
lastIndexOf
Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the highest indexi
such thatObjects.equals(o, get(i))
, or -1 if there is no such index.- Parameters:
o
- element to search for- Returns:
- the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element
- Throws:
ClassCastException
- 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
ListIterator<E> listIterator()Returns a list iterator over the elements in this list (in proper sequence).- Returns:
- a list iterator over the elements in this list (in proper sequence)
-
listIterator
Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list. The specified index indicates the first element that would be returned by an initial call tonext
. An initial call toprevious
would return the element with the specified index minus one.- Parameters:
index
- index of the first element to be returned from the list iterator (by a call tonext
)- Returns:
- a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list
- Throws:
IndexOutOfBoundsException
- if the index is out of range (index < 0 || index > size()
)
-
subList
Returns a view of the portion of this list between the specifiedfromIndex
, inclusive, andtoIndex
, exclusive. (IffromIndex
andtoIndex
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:
Similar idioms may be constructed forlist.subList(from, to).clear();
indexOf
andlastIndexOf
, and all of the algorithms in theCollections
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.)
- Parameters:
fromIndex
- low endpoint (inclusive) of the subListtoIndex
- high endpoint (exclusive) of the subList- Returns:
- a view of the specified range within this list
- Throws:
IndexOutOfBoundsException
- for an illegal endpoint index value (fromIndex < 0 || toIndex > size || fromIndex > toIndex
)
-
spliterator
Creates aSpliterator
over the elements in this list.The
Spliterator
reportsSpliterator.SIZED
andSpliterator.ORDERED
. Implementations should document the reporting of additional characteristic values.- Specified by:
spliterator
in interfaceCollection<E>
- Specified by:
spliterator
in interfaceIterable<E>
- Implementation Requirements:
- The default implementation creates a
late-binding
spliterator as follows:
- If the list is an instance of
RandomAccess
then the default implementation creates a spliterator that traverses elements by invoking the methodget(int)
. If such invocation results or would result in anIndexOutOfBoundsException
then the spliterator will fail-fast and throw aConcurrentModificationException
. If the list is also an instance ofAbstractList
then the spliterator will use the list'smodCount
field to provide additional fail-fast behavior. - Otherwise, the default implementation creates a spliterator from the
list's
Iterator
. The spliterator inherits the fail-fast of the list's iterator.
- If the list is an instance of
- Implementation Note:
- The created
Spliterator
additionally reportsSpliterator.SUBSIZED
. - Returns:
- a
Spliterator
over the elements in this list - Since:
- 1.8
-
addFirst
Adds an element as the first element of this collection (optional operation). After this operation completes normally, the given element will be a member of this collection, and it will be the first element in encounter order.- Specified by:
addFirst
in interfaceSequencedCollection<E>
- Implementation Requirements:
- The implementation in this interface calls
add(0, e)
. - Parameters:
e
- the element to be added- Throws:
NullPointerException
- if the specified element is null and this collection does not permit null elementsUnsupportedOperationException
- if this collection implementation does not support this operation- Since:
- 21
-
addLast
Adds an element as the last element of this collection (optional operation). After this operation completes normally, the given element will be a member of this collection, and it will be the last element in encounter order.- Specified by:
addLast
in interfaceSequencedCollection<E>
- Implementation Requirements:
- The implementation in this interface calls
add(e)
. - Parameters:
e
- the element to be added.- Throws:
NullPointerException
- if the specified element is null and this collection does not permit null elementsUnsupportedOperationException
- if this collection implementation does not support this operation- Since:
- 21
-
getFirst
Gets the first element of this collection.- Specified by:
getFirst
in interfaceSequencedCollection<E>
- Implementation Requirements:
- If this List is not empty, the implementation in this interface returns the result
of calling
get(0)
. Otherwise, it throwsNoSuchElementException
. - Returns:
- the retrieved element
- Throws:
NoSuchElementException
- if this collection is empty- Since:
- 21
-
getLast
Gets the last element of this collection.- Specified by:
getLast
in interfaceSequencedCollection<E>
- Implementation Requirements:
- If this List is not empty, the implementation in this interface returns the result
of calling
get(size() - 1)
. Otherwise, it throwsNoSuchElementException
. - Returns:
- the retrieved element
- Throws:
NoSuchElementException
- if this collection is empty- Since:
- 21
-
removeFirst
Removes and returns the first element of this collection (optional operation).- Specified by:
removeFirst
in interfaceSequencedCollection<E>
- Implementation Requirements:
- If this List is not empty, the implementation in this interface returns the result
of calling
remove(0)
. Otherwise, it throwsNoSuchElementException
. - Returns:
- the removed element
- Throws:
NoSuchElementException
- if this collection is emptyUnsupportedOperationException
- if this collection implementation does not support this operation- Since:
- 21
-
removeLast
Removes and returns the last element of this collection (optional operation).- Specified by:
removeLast
in interfaceSequencedCollection<E>
- Implementation Requirements:
- If this List is not empty, the implementation in this interface returns the result
of calling
remove(size() - 1)
. Otherwise, it throwsNoSuchElementException
. - Returns:
- the removed element
- Throws:
NoSuchElementException
- if this collection is emptyUnsupportedOperationException
- if this collection implementation does not support this operation- Since:
- 21
-
reversed
Returns a reverse-ordered view of this collection. The encounter order of elements in the returned view is the inverse of the encounter order of elements in this collection. The reverse ordering affects all order-sensitive operations, including those on the view collections of the returned view. If the collection implementation permits modifications to this view, the modifications "write through" to the underlying collection. Changes to the underlying collection might or might not be visible in this reversed view, depending upon the implementation.- Specified by:
reversed
in interfaceSequencedCollection<E>
- Implementation Requirements:
- The implementation in this interface returns a reverse-ordered List
view. The
reversed()
method of the view returns a reference to this List. Other operations on the view are implemented via calls to public methods on this List. The exact relationship between calls on the view and calls on this List is unspecified. However, order-sensitive operations generally behave as if they delegate to the appropriate method with the opposite orientation. For example, callinggetFirst
on the view might result in a call togetLast
on this List. - Returns:
- a reverse-ordered view of this collection, as a
List
- Since:
- 21
-
of
Returns an unmodifiable list containing zero elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Returns:
- an empty
List
- Since:
- 9
-
of
Returns an unmodifiable list containing one element. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- the single element- Returns:
- a
List
containing the specified element - Throws:
NullPointerException
- if the element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing two elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- the first elemente2
- the second element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing three elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- the first elemente2
- the second elemente3
- the third element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing four elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- the first elemente2
- the second elemente3
- the third elemente4
- the fourth element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing five elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- the first elemente2
- the second elemente3
- the third elemente4
- the fourth elemente5
- the fifth element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing six elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- the first elemente2
- the second elemente3
- the third elemente4
- the fourth elemente5
- the fifth elemente6
- the sixth element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing seven elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- the first elemente2
- the second elemente3
- the third elemente4
- the fourth elemente5
- the fifth elemente6
- the sixth elemente7
- the seventh element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing eight elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- the first elemente2
- the second elemente3
- the third elemente4
- the fourth elemente5
- the fifth elemente6
- the sixth elemente7
- the seventh elemente8
- the eighth element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing nine elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- 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 element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing ten elements. See Unmodifiable Lists for details.- Type Parameters:
E
- theList
's element type- Parameters:
e1
- 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 element- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
- Since:
- 9
-
of
Returns an unmodifiable list containing an arbitrary number of elements. See Unmodifiable Lists for details.- API Note:
- This method also accepts a single array as an argument. The element type of
the resulting list will be the component type of the array, and the size of
the list will be equal to the length of the array. To create a list with
a single element that is an array, do the following:
This will cause theString[] array = ... ; List<String[]> list = List.<String[]>of(array);
List.of(E)
method to be invoked instead. - Type Parameters:
E
- theList
's element type- Parameters:
elements
- the elements to be contained in the list- Returns:
- a
List
containing the specified elements - Throws:
NullPointerException
- if an element isnull
or if the array isnull
- Since:
- 9
-
copyOf
Returns an unmodifiable List containing the elements of the given Collection, in its iteration order. The given Collection must not be null, and it must not contain any null elements. If the given Collection is subsequently modified, the returned List will not reflect such modifications.- Implementation Note:
- If the given Collection is an unmodifiable List, calling copyOf will generally not create a copy.
- Type Parameters:
E
- theList
's element type- Parameters:
coll
- aCollection
from which elements are drawn, must be non-null- Returns:
- a
List
containing the elements of the givenCollection
- Throws:
NullPointerException
- if coll is null, or if it contains any nulls- Since:
- 10
-