compact1, compact2, compact3

java.util

Class AbstractList<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

All Implemented Interfaces:

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

Direct Known Subclasses:

AbstractSequentialList, ArrayList, Vector

public abstract class AbstractList<E>
extends AbstractCollection<E>
implements List<E>

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

To implement an unmodifiable list, the programmer needs only to extend this class and provide implementations for the get(int) and size() methods.

To implement a modifiable list, the programmer must additionally override the set(int, E) method (which otherwise throws an UnsupportedOperationException). If the list is variable-size the programmer must additionally override the add(int, E) and remove(int) methods.

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

Unlike the other abstract collection implementations, the programmer does not have to provide an iterator implementation; the iterator and list iterator are implemented by this class, on top of the "random access" methods: get(int), set(int, E), add(int, E) and remove(int).

The documentation for each non-abstract method in this class describes its implementation in detail. Each of these methods may be overridden if the collection being implemented admits a more efficient implementation.

This class is a member of the Java Collections Framework.

Since:

1.2

Field Summary

Fields

Modifier and Type	Field	Description
protected int	modCount	The number of times this list has been structurally modified.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractList()	Sole constructor.

Method Summary

Modifier and Type	Method	Description
boolean	add(E e)	Appends the specified element to the end of this list (optional operation).
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).
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()	Returns a list iterator over the elements in this list (in proper sequence).
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.
E	remove(int index)	Removes the element at the specified position in this list (optional operation).
protected 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.

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, replaceAll, retainAll, size, sort, spliterator, toArray, toArray

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

modCount

protected transient int modCount

The number of times this list has been structurally modified. Structural modifications are those that change the size of the list, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results.

This field is used by the iterator and list iterator implementation returned by the iterator and listIterator methods. If the value of this field changes unexpectedly, the iterator (or list iterator) will throw a ConcurrentModificationException in response to the next, remove, previous, set or add operations. This provides fail-fast behavior, rather than non-deterministic behavior in the face of concurrent modification during iteration.

Use of this field by subclasses is optional. If a subclass wishes to provide fail-fast iterators (and list iterators), then it merely has to increment this field in its add(int, E) and remove(int) methods (and any other methods that it overrides that result in structural modifications to the list). A single call to add(int, E) or remove(int) must add no more than one to this field, or the iterators (and list iterators) will throw bogus ConcurrentModificationExceptions. If an implementation does not wish to provide fail-fast iterators, this field may be ignored.

Constructor Detail

AbstractList

protected AbstractList()

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

Method Detail

add

public boolean add(E e)

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.

This implementation calls add(size(), e).

Note that this implementation throws an UnsupportedOperationException unless add(int, E) is overridden.

Specified by:

add in interface Collection<E>

Specified by:

add in interface List<E>

Overrides: