AbstractSequentialList

public abstract class AbstractSequentialList extends AbstractList<E>
Known Direct Subclasses

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.

Inherited Field Summary

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

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

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

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

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)

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

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