AbstractSequentialList

public abstract class AbstractSequentialList extends AbstractList<E>

Known Direct Subclasses LinkedList<E> LinkedList<E> Doubly-linked list implementation of the List and Deque interfaces.

This class provides a skeletal implementation of the List interface to minimize the effort required to implement this interface backed by a "sequential access" data store (such as a linked list). For random access data (such as an array), AbstractList should be used in preference to this class.

This class is the opposite of the AbstractList class in the sense that it implements the "random access" methods (get(int index), set(int index, E element), add(int index, E element) and remove(int index)) on top of the list's list iterator, instead of the other way around.

To implement a list the programmer needs only to extend this class and provide implementations for the listIterator and size methods. For an unmodifiable list, the programmer need only implement the list iterator's hasNext, next, hasPrevious, previous and index methods.

For a modifiable list the programmer should additionally implement the list iterator's set method. For a variable-size list the programmer should additionally implement the list iterator's remove and add methods.

The programmer should generally provide a void (no argument) and collection constructor, as per the recommendation in the Collection interface specification.

This class is a member of the Java Collections Framework.

See Also

• Collection
• List
• AbstractList
• AbstractCollection

Inherited Field Summary

From class java.util.AbstractList

protected int

modCount

The number of times this list has been structurally modified.

Protected Constructor Summary

AbstractSequentialList() Sole constructor.

Public Method Summary

void	add(int index, E element) Inserts the specified element at the specified position in 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).
E	get(int index) Returns the element at the specified position in this list.
Iterator<E>	iterator() Returns an iterator over the elements in this list (in proper sequence).
abstract ListIterator<E>	listIterator(int index) Returns a list iterator over the elements in this list (in proper sequence).
E	remove(int index) Removes the element at the specified position in this list (optional operation).
E	set(int index, E element) Replaces the element at the specified position in this list with the specified element (optional operation).

Inherited Method Summary

From class java.util.AbstractList

void	add(int index, E element) Inserts the specified element at the specified position in this list (optional operation).
boolean	add(E e) 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).
void	clear() Removes all of the elements from this list (optional operation).
boolean	equals(Object o) Compares the specified object with this list for equality.
abstract 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.
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(int index) Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list.
ListIterator<E>	listIterator() Returns a list iterator over the elements in this list (in proper sequence).
E	remove(int index) Removes the element at the specified position in this list (optional operation).
void	removeRange(int fromIndex, int toIndex) Removes from this list all of the elements whose index is between fromIndex, inclusive, and toIndex, exclusive.
E	set(int index, E element) Replaces the element at the specified position in this list with the specified element (optional operation).
List<E>	subList(int fromIndex, int toIndex) Returns a view of the portion of this list between the specified fromIndex, inclusive, and toIndex, exclusive.

From class java.util.AbstractCollection

boolean	add(E e) Ensures that this collection contains the specified element (optional operation). This implementation always throws an UnsupportedOperationException.
boolean	addAll(Collection<? extends E> c) Adds all of the elements in the specified collection to this collection (optional operation). This implementation iterates over the specified collection, and adds each object returned by the iterator to this collection, in turn.
void	clear() Removes all of the elements from this collection (optional operation). This implementation iterates over this collection, removing each element using the Iterator.remove operation.
boolean	contains(Object o) Returns true if this collection contains the specified element. This implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.
boolean	containsAll(Collection<?> c) Returns true if this collection contains all of the elements in the specified collection. This implementation iterates over the specified collection, checking each element returned by the iterator in turn to see if it's contained in this collection.
boolean	isEmpty() Returns true if this collection contains no elements. This implementation returns size() == 0.
abstract Iterator<E>	iterator() Returns an iterator over the elements contained in this collection.
boolean	remove(Object o) Removes a single instance of the specified element from this collection, if it is present (optional operation). This implementation iterates over the collection looking for the specified element.
boolean	removeAll(Collection<?> c) Removes all of this collection's elements that are also contained in the specified collection (optional operation). This implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection.
boolean	retainAll(Collection<?> c) Retains only the elements in this collection that are contained in the specified collection (optional operation). This implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection.
abstract int	size() Returns the number of elements in this collection.
<T> T[]	toArray(T[] contents) Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. This implementation returns an array containing all the elements returned by this collection's iterator in the same order, stored in consecutive elements of the array, starting with index 0.
Object[]	toArray() Returns an array containing all of the elements in this collection. This implementation returns an array containing all the elements returned by this collection's iterator, in the same order, stored in consecutive elements of the array, starting with index 0.
String	toString() Returns a string representation of this collection.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.util.List

abstract boolean	add(E e) Appends the specified element to the end of this list (optional operation).
abstract void	add(int index, E element) Inserts the specified element at the specified position in this list (optional operation).
abstract 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).
abstract 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).
abstract void	clear() Removes all of the elements from this list (optional operation).
abstract boolean	contains(Object o) Returns true if this list contains the specified element.
abstract boolean	containsAll(Collection<?> c) Returns true if this list contains all of the elements of the specified collection.
abstract boolean	equals(Object o) Compares the specified object with this list for equality.
abstract E	get(int index) Returns the element at the specified position in this list.
abstract int	hashCode() Returns the hash code value for this list.
abstract 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.
abstract boolean	isEmpty() Returns true if this list contains no elements.
abstract Iterator<E>	iterator() Returns an iterator over the elements in this list in proper sequence.
abstract 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.
abstract 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.
abstract ListIterator<E>	listIterator() Returns a list iterator over the elements in this list (in proper sequence).
abstract E	remove(int index) Removes the element at the specified position in this list (optional operation).
abstract boolean	remove(Object o) Removes the first occurrence of the specified element from this list, if it is present (optional operation).
abstract boolean	removeAll(Collection<?> c) Removes from this list all of its elements that are contained in the specified collection (optional operation).
void	replaceAll(UnaryOperator<E> operator) Replaces each element of this list with the result of applying the operator to that element.
abstract boolean	retainAll(Collection<?> c) Retains only the elements in this list that are contained in the specified collection (optional operation).
abstract E	set(int index, E element) Replaces the element at the specified position in this list with the specified element (optional operation).
abstract int	size() Returns the number of elements in this list.
void	sort(Comparator<? super E> c) Sorts this list according to the order induced by the specified Comparator.
Spliterator<E>	spliterator() Creates a Spliterator over the elements in this list.
abstract List<E>	subList(int fromIndex, int toIndex) Returns a view of the portion of this list between the specified fromIndex, inclusive, and toIndex, exclusive.
abstract Object[]	toArray() Returns an array containing all of the elements in this list in proper sequence (from first to last element).
abstract <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.

From interface java.util.Collection

abstract boolean	add(E e) Ensures that this collection contains the specified element (optional operation).
abstract boolean	addAll(Collection<? extends E> c) Adds all of the elements in the specified collection to this collection (optional operation).
abstract void	clear() Removes all of the elements from this collection (optional operation).
abstract boolean	contains(Object o) Returns true if this collection contains the specified element.
abstract boolean	containsAll(Collection<?> c) Returns true if this collection contains all of the elements in the specified collection.
abstract boolean	equals(Object o) Compares the specified object with this collection for equality.
abstract int	hashCode() Returns the hash code value for this collection.
abstract boolean	isEmpty() Returns true if this collection contains no elements.
abstract Iterator<E>	iterator() Returns an iterator over the elements in this collection.
Stream<E>	parallelStream() Returns a possibly parallel Stream with this collection as its source.
abstract boolean	remove(Object o) Removes a single instance of the specified element from this collection, if it is present (optional operation).
abstract boolean	removeAll(Collection<?> c) Removes all of this collection's elements that are also contained in the specified collection (optional operation).
boolean	removeIf(Predicate<? super E> filter) Removes all of the elements of this collection that satisfy the given predicate.
abstract boolean	retainAll(Collection<?> c) Retains only the elements in this collection that are contained in the specified collection (optional operation).
abstract int	size() Returns the number of elements in this collection.
Spliterator<E>	spliterator() Creates a Spliterator over the elements in this collection.
Stream<E>	stream() Returns a sequential Stream with this collection as its source.
abstract <T> T[]	toArray(T[] a) Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
abstract Object[]	toArray() Returns an array containing all of the elements in this collection.

From interface java.lang.Iterable

void	forEach(Consumer<? super T> action) Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception.
abstract Iterator<E>	iterator() Returns an iterator over elements of type T.
Spliterator<E>	spliterator() Creates a Spliterator over the elements described by this Iterable.

Protected Constructors

protected AbstractSequentialList ()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

Public Methods

public void add (int index, E element)

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).

This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it inserts the specified element with ListIterator.add.

Note that this implementation will throw an UnsupportedOperationException if the list iterator does not implement the add operation.

Parameters

index	index at which the specified element is to be inserted
element	element to be inserted

Throws

UnsupportedOperationException
ClassCastException
NullPointerException
IllegalArgumentException
IndexOutOfBoundsException

public 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). 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.)

This implementation gets an iterator over the specified collection and a list iterator over this list pointing to the indexed element (with listIterator(index)). Then, it iterates over the specified collection, inserting the elements obtained from the iterator into this list, one at a time, using ListIterator.add followed by ListIterator.next (to skip over the added element).

Note that this implementation will throw an UnsupportedOperationException if the list iterator returned by the listIterator method does not implement the add operation.

Parameters

index	index at which to insert the first element from the specified collection
c	collection containing elements to be added to this list

Returns

• true if this list changed as a result of the call

Throws

UnsupportedOperationException
ClassCastException
NullPointerException
IllegalArgumentException
IndexOutOfBoundsException

public E get (int index)

Returns the element at the specified position in this list.

This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it gets the element using ListIterator.next and returns it.

Parameters

index	index of the element to return

Returns

• the element at the specified position in this list

Throws

IndexOutOfBoundsException

public Iterator<E> iterator ()

Returns an iterator over the elements in this list (in proper sequence).

This implementation merely returns a list iterator over the list.

Returns

• an iterator over the elements in this list (in proper sequence)

public abstract ListIterator<E> listIterator (int index)

Returns a list iterator over the elements in this list (in proper sequence).

Parameters

index	index of first element to be returned from the list iterator (by a call to the next method)

Returns

• a list iterator over the elements in this list (in proper sequence)

Throws

IndexOutOfBoundsException

public E remove (int index)

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.

This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it removes the element with ListIterator.remove.

Note that this implementation will throw an UnsupportedOperationException if the list iterator does not implement the remove operation.

Parameters

index	the index of the element to be removed

Returns

• the element previously at the specified position

Throws

UnsupportedOperationException
IndexOutOfBoundsException

public E set (int index, E element)

Replaces the element at the specified position in this list with the specified element (optional operation).

This implementation first gets a list iterator pointing to the indexed element (with listIterator(index)). Then, it gets the current element using ListIterator.next and replaces it with ListIterator.set.

Note that this implementation will throw an UnsupportedOperationException if the list iterator does not implement the set operation.

Parameters

index	index of the element to replace
element	element to be stored at the specified position

Returns

• the element previously at the specified position

Throws

UnsupportedOperationException
ClassCastException
NullPointerException
IllegalArgumentException
IndexOutOfBoundsException