java.util

Class AbstractSequentialList<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

java.util.AbstractSequentialList<E>

All Implemented Interfaces:

Iterable<E>, Collection<E>, List<E>

Direct Known Subclasses:

LinkedList

public abstract class AbstractSequentialList<E>
extends AbstractList<E>

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.

Since:

1.2

Author:

Josh Bloch, Neal Gafter

See Also:

Collection, List, AbstractList, AbstractCollection

Field Summary

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractSequentialList() Sole constructor.

Method Summary

Methods

Modifier and Type	Method and Description
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).

Methods inherited from class java.util.AbstractList

add, clear, equals, hashCode, indexOf, lastIndexOf, listIterator, removeRange, subList

Methods inherited from class java.util.AbstractCollection

addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, size, toArray, toArray, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.List

addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, size, toArray, toArray

Constructor Detail

AbstractSequentialList

protected AbstractSequentialList()

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

Method Detail

get

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.

Specified by:

get in interface List<E>

Specified by:

get in class AbstractList<E>

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

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.

Specified by:

set in interface List<E>

Overrides:

set in class AbstractList<E>

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 - if the set operation is not supported by this list

ClassCastException - if the class of the specified element prevents it from being added to this list

NullPointerException - if the specified element is null and this list does not permit null elements

IllegalArgumentException - if some property of the specified element prevents it from being added to this list

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())

add

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.

Specified by:

add in interface List<E>

Overrides:

add in class AbstractList<E>

Parameters:

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

element - element to be inserted

Throws:

UnsupportedOperationException - if the add operation is not supported by this list

ClassCastException - if the class of the specified element prevents it from being added to this list

NullPointerException - if the specified element is null and this list does not permit null elements

IllegalArgumentException - if some property of the specified element prevents it from being added to this list

IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())

remove

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.

Specified by:

remove in interface List<E>

Overrides:

remove in class AbstractList<E>

Parameters:

index - the index of the element to be removed

Returns:

the element previously at the specified position

Throws:

UnsupportedOperationException - if the remove operation is not supported by this list

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())

addAll

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.

Specified by:

addAll in interface List<E>

Overrides:

addAll in class AbstractList<E>

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 - if the addAll operation is not supported by this list

ClassCastException - if the class of an element of the specified collection prevents it from being added to this list

NullPointerException - if the specified collection contains one or more null elements and this list does not permit null elements, or if the specified collection is null

IllegalArgumentException - if some property of an element of the specified collection prevents it from being added to this list

IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())

iterator

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.

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface List<E>

Overrides:

iterator in class AbstractList<E>

Returns:

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

listIterator

public abstract ListIterator<E> listIterator(int index)

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

Specified by:

listIterator in interface List<E>

Overrides:

listIterator in class AbstractList<E>

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 - if the index is out of range (index < 0 || index > size())