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java.util
Class AbstractSequentialList

java.lang.Object
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  +--java.util.AbstractCollection
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        +--java.util.AbstractList
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              +--java.util.AbstractSequentialList

Direct Known Subclasses:

LinkedList

public abstract class AbstractSequentialList

extends AbstractList

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, Object element), set(int index, Object element), add(int index, Object 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.

Since:

JDK1.2

See Also:

Collection, List, AbstractList, AbstractCollection

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

protected

AbstractSequentialList() Sole constructor.

Method Summary

void	add(int index, Object element) Inserts the specified element at the specified position in this list.
boolean	addAll(int index, Collection c) Inserts all of the elements in in the specified collection into this list at the specified position.
Object	get(int index) Returns the element at the specified position in this list.
Iterator	iterator() Returns an iterator over the elements in this list (in proper sequence).
abstract ListIterator	listIterator(int index) Returns a list iterator over the elements in this list (in proper sequence).
Object	remove(int index) Removes the element at the specified position in this list.
Object	set(int index, Object element) Replaces the element at the specified position in this list with the specified element.

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

Constructor Detail

AbstractSequentialList

protected AbstractSequentialList()

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

Method Detail

get

public Object 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.

Overrides:

get in class AbstractList

Returns:

the element at the specified position in this list. * @param index index of element to return. * @throws IndexOutOfBoundsException if the specified index is out of range (index < 0 || index >= size()).

set

public Object set(int index,
                  Object element)

Replaces the element at the specified position in this list with the specified element.

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 list iterator does not implement the set operation.

Overrides:

set in class AbstractList

Parameters:

index - index of element to replace.

element - element to be stored at the specified position.

Returns:

the element previously at the specified position.

Throws:

UnsupportedOperationException - set is not supported by this list.

NullPointerException - this list does not permit null elements and one of the elements of c is null.

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

IllegalArgumentException - some aspect of the specified element prevents it from being added to this list.

IndexOutOfBoundsException - index out of range (index < 0 || index >= size()).

IllegalArgumentException - fromIndex > toIndex.

add

public void add(int index,
                Object element)

Inserts the specified element at the specified position in this list. 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 list iterator does not implement the add operation.

Overrides:

add in class AbstractList

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.

NullPointerException - this list does not permit null elements and one of the elements of c is null.

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

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

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

remove

public Object remove(int index)

Removes the element at the specified position in this list. Shifts any subsequent elements to the left (subtracts one from their indices).

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 list iterator does not implement the remove operation.

Overrides:

remove in class AbstractList

Parameters:

the - index of the element to be removed from the List.

Returns:

the element that was removed from the list.

Throws:

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

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

addAll

public boolean addAll(int index,
                      Collection c)

Inserts all of the elements in in the specified collection into this list at the specified position. 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 the list in the order that they are returned by the specified collection's iterator. The behavior of this operation is unspecified 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.) Optional operation.

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.

Overrides:

addAll in class AbstractList

Parameters:

index - index at which to insert first element from the specified collection.

c - elements to be inserted into 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.

NullPointerException - this list does not permit null elements and one of the elements of the specified collection is null.

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

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

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

iterator

public Iterator iterator()

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

This implementation merely returns a list iterator over the list.

Overrides:

iterator in class AbstractList

Returns:

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

listIterator

public abstract ListIterator listIterator(int index)

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

Overrides:

listIterator in class AbstractList

Returns:

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