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>

AbstractList is an abstract implementation of the List interface, optimized for a backing store which supports random access. This implementation does not support adding or replacing. A subclass must implement the abstract methods get() and size(), and to create a modifiable List it's necessary to override the add() method that currently throws an UnsupportedOperationException.

Since:

1.2

Field Summary

Fields

Modifier and Type	Field and Description
protected int	modCount A counter for changes to the list.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractList() Constructs a new instance of this AbstractList.

Method Summary

Modifier and Type	Method and Description
boolean	add(E object) Adds the specified object at the end of this List.
void	add(int location, E object) Inserts the specified object into this List at the specified location.
boolean	addAll(int location, Collection<? extends E> collection) Inserts the objects in the specified Collection at the specified location in this List.
void	clear() Removes all elements from this list, leaving it empty.
boolean	equals(Object object) Compares the specified object to this list and return true if they are equal.
abstract E	get(int location) Returns the element at the specified location in this list.
int	hashCode() Returns the hash code of this list.
int	indexOf(Object object) Searches this list for the specified object and returns the index of the first occurrence.
Iterator<E>	iterator() Returns an iterator on the elements of this list.
int	lastIndexOf(Object object) Searches this list for the specified object and returns the index of the last occurrence.
ListIterator<E>	listIterator() Returns a ListIterator on the elements of this list.
ListIterator<E>	listIterator(int location) Returns a list iterator on the elements of this list.
E	remove(int location) Removes the object at the specified location from this list.
protected void	removeRange(int start, int end) Removes the objects in the specified range from the start to the end index minus one.
E	set(int location, E object) Replaces the element at the specified location in this list with the specified object.
List<E>	subList(int start, int end) Returns a part of consecutive elements of this list as a view.
Object[]	toArray() Returns a new array containing all elements contained in this ArrayList.
<T> T[]	toArray(T[] contents) Returns an array containing all elements contained in this ArrayList.

Methods inherited from class java.util.AbstractCollection

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

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.List

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

Field Detail

modCount

protected transient int modCount

A counter for changes to the list.

Constructor Detail

AbstractList

protected AbstractList()

Constructs a new instance of this AbstractList.

Method Detail

add

public void add(int location,
                E object)

Inserts the specified object into this List at the specified location. The object is inserted before any previous element at the specified location. If the location is equal to the size of this List, the object is added at the end.

Concrete implementations that would like to support the add functionality must override this method.

Specified by:

add in interface List<E>

Parameters:

location - the index at which to insert.

object - the object to add.

Throws:

UnsupportedOperationException - if adding to this List is not supported.

ClassCastException - if the class of the object is inappropriate for this List

IllegalArgumentException - if the object cannot be added to this List

IndexOutOfBoundsException - if location < 0 || >= size()

add

public boolean add(E object)

Adds the specified object at the end of this List.

Specified by:

add in interface Collection<E>

Specified by:

add in interface List<E>

Overrides:

add in class AbstractCollection<E>

Parameters:

object - the object to add

Returns:

true

Throws:

UnsupportedOperationException - if adding to this List is not supported

ClassCastException - if the class of the object is inappropriate for this List

IllegalArgumentException - if the object cannot be added to this List

addAll

public boolean addAll(int location,
                      Collection<? extends E> collection)

Inserts the objects in the specified Collection at the specified location in this List. The objects are added in the order they are returned from the collection's iterator.

Specified by:

addAll in interface List<E>

Parameters:

location - the index at which to insert.

collection - the Collection of objects

Returns:

true if this List is modified, false otherwise.

Throws:

UnsupportedOperationException - if adding to this list is not supported.

ClassCastException - if the class of an object is inappropriate for this list.

IllegalArgumentException - if an object cannot be added to this list.

IndexOutOfBoundsException - if location < 0 || > size()

clear

public void clear()

Removes all elements from this list, leaving it empty.

Specified by:

clear in interface Collection<E>

Specified by:

clear in interface List<E>

Overrides:

clear in class AbstractCollection<E>

Throws:

UnsupportedOperationException - if removing from this list is not supported.

See Also:

List.isEmpty(), List.size()

equals

public boolean equals(Object object)

Compares the specified object to this list and return true if they are equal. Two lists are equal when they both contain the same objects in the same order.

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface List<E>

Overrides:

equals in class Object

Parameters:

object - the object to compare to this object.

Returns:

true if the specified object is equal to this list, false otherwise.

See Also:

hashCode()

get

public abstract E get(int location)

Returns the element at the specified location in this list.

Specified by:

get in interface List<E>

Parameters:

location - the index of the element to return.

Returns:

the element at the specified index.

Throws:

IndexOutOfBoundsException - if location < 0 || >= size()

hashCode

public int hashCode()

Returns the hash code of this list. The hash code is calculated by taking each element's hashcode into account.

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface List<E>

Overrides:

hashCode in class Object

Returns:

the hash code.

See Also:

equals(java.lang.Object), List.hashCode()

indexOf

public int indexOf(Object object)

Searches this list for the specified object and returns the index of the first occurrence.

Specified by:

indexOf in interface List<E>

Parameters:

object - the object to search for.

Returns:

the index of the first occurrence of the object, or -1 if it was not found.

iterator

public Iterator<E> iterator()

Returns an iterator on the elements of this list. The elements are iterated in the same order as they occur in the list.

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface List<E>

Specified by:

iterator in class AbstractCollection<E>

Returns:

an iterator on the elements of this list.

See Also:

Iterator

lastIndexOf

public int lastIndexOf(Object object)

Searches this list for the specified object and returns the index of the last occurrence.

Specified by:

lastIndexOf in interface List<E>

Parameters:

object - the object to search for.

Returns:

the index of the last occurrence of the object, or -1 if the object was not found.

listIterator

public ListIterator<E> listIterator()

Returns a ListIterator on the elements of this list. The elements are iterated in the same order that they occur in the list.

Specified by:

listIterator in interface List<E>

Returns:

a ListIterator on the elements of this list

See Also:

ListIterator

listIterator

public ListIterator<E> listIterator(int location)

Returns a list iterator on the elements of this list. The elements are iterated in the same order as they occur in the list. The iteration starts at the specified location.

Specified by:

listIterator in interface List<E>

Parameters:

location - the index at which to start the iteration.

Returns:

a ListIterator on the elements of this list.

Throws:

IndexOutOfBoundsException - if location < 0 || location > size()

See Also:

ListIterator

remove

public E remove(int location)

Removes the object at the specified location from this list.

Specified by:

remove in interface List<E>

Parameters:

location - the index of the object to remove.

Returns:

the removed object.

Throws:

UnsupportedOperationException - if removing from this list is not supported.

IndexOutOfBoundsException - if location < 0 || >= size()

removeRange

protected void removeRange(int start,
                           int end)

Removes the objects in the specified range from the start to the end index minus one.

Parameters:

start - the index at which to start removing.

end - the index after the last element to remove.

Throws:

UnsupportedOperationException - if removing from this list is not supported.

IndexOutOfBoundsException - if start < 0 or start >= size().

set

public E set(int location,
             E object)

Replaces the element at the specified location in this list with the specified object.

Specified by:

set in interface List<E>

Parameters:

location - the index at which to put the specified object.

object - the object to add.

Returns:

the previous element at the index.

Throws:

UnsupportedOperationException - if replacing elements in this list is not supported.

ClassCastException - if the class of an object is inappropriate for this list.

IllegalArgumentException - if an object cannot be added to this list.

IndexOutOfBoundsException - if location < 0 || >= size()

subList

public List<E> subList(int start,
                       int end)

Returns a part of consecutive elements of this list as a view. The returned view will be of zero length if start equals end. Any change that occurs in the returned subList will be reflected to the original list, and vice-versa. All the supported optional operations by the original list will also be supported by this subList.

This method can be used as a handy method to do some operations on a sub range of the original list, for example list.subList(from, to).clear();

If the original list is modified in other ways than through the returned subList, the behavior of the returned subList becomes undefined.

The returned subList is a subclass of AbstractList. The subclass stores offset, size of itself, and modCount of the original list. If the original list implements RandomAccess interface, the returned subList also implements RandomAccess interface.

The subList's set(int, Object), get(int), add(int, Object), remove(int), addAll(int, Collection) and removeRange(int, int) methods first check the bounds, adjust offsets and then call the corresponding methods of the original AbstractList. addAll(Collection c) method of the returned subList calls the original addAll(offset + size, c).

The listIterator(int) method of the subList wraps the original list iterator. The iterator() method of the subList invokes the original listIterator() method, and the size() method merely returns the size of the subList.

All methods will throw a ConcurrentModificationException if the modCount of the original list is not equal to the expected value.

Specified by:

subList in interface List<E>

Parameters:

start - start index of the subList (inclusive).

end - end index of the subList, (exclusive).

Returns:

a subList view of this list starting from start (inclusive), and ending with end (exclusive)

Throws:

IndexOutOfBoundsException - if (start < 0 || end > size())

IllegalArgumentException - if (start > end)

toArray

public Object[] toArray()

Returns a new array containing all elements contained in this ArrayList.

Specified by:

toArray in interface Collection<E>

Specified by:

toArray in interface List<E>

Overrides:

toArray in class AbstractCollection<E>

Returns:

an array of the elements from this ArrayList

toArray

public <T> T[] toArray(T[] contents)

Returns an array containing all elements contained in this ArrayList. If the specified array is large enough to hold the elements, the specified array is used, otherwise an array of the same type is created. If the specified array is used and is larger than this ArrayList, the array element following the collection elements is set to null.

Specified by:

toArray in interface Collection<E>

Specified by:

toArray in interface List<E>

Overrides:

toArray in class AbstractCollection<E>

Parameters:

contents - the array.

Returns:

an array of the elements from this ArrayList.

Throws:

ArrayStoreException - when the type of an element in this ArrayList cannot be stored in the type of the specified array.