public class

ArrayList

extends AbstractList<E>
implements Serializable Cloneable List<E> RandomAccess

java.lang.Object
↳	java.util.AbstractCollection<E>
	↳	java.util.AbstractList<E>
		↳	java.util.ArrayList<E>

Class Overview

ArrayList is an implementation of List, backed by an array. All optional operations are supported, adding, removing, and replacing. The elements can be any objects.

Summary

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Inherited Fields

From class java.util.AbstractList

Public Constructors
	ArrayList() Constructs a new instance of ArrayList with zero capacity.
	ArrayList(int capacity) Constructs a new instance of ArrayList with the specified capacity.
	ArrayList(Collection<? extends E> collection) Constructs a new instance of ArrayList containing the elements in the specified collection.

Public Methods
void	add(int location, E object) Inserts the specified object into this ArrayList at the specified location.
boolean	add(E object) Adds the specified object at the end of this ArrayList.
boolean	addAll(int location, Collection<? extends E> collection) Inserts the objects in the specified Collection at the specified location in this ArrayList.
boolean	addAll(Collection<? extends E> collection) Adds the objects in the specified Collection to this ArrayList.
void	clear() Removes all elements from this ArrayList, leaving it empty.
Object	clone() Returns a new ArrayList with the same elements, size and capacity as this ArrayList.
boolean	contains(Object object) Searches this ArrayList for the specified object.
void	ensureCapacity(int minimumCapacity) Ensures that this ArrayList can hold the specified number of elements without growing.
E	get(int location) Returns the element at the specified location in this ArrayList.
int	indexOf(Object object) Searches this ArrayList for the specified object and returns the index of the first occurrence.
boolean	isEmpty() Returns if this ArrayList has no elements, a size of zero.
int	lastIndexOf(Object object) Searches this ArrayList for the specified object and returns the index of the last occurrence.
E	remove(int location) Removes the object at the specified location from this ArrayList.
boolean	remove(Object object) Removes the first occurrence of the specified object from this Collection.
E	set(int location, E object) Replaces the element at the specified location in this ArrayList with the specified object.
int	size() Returns the number of elements in this ArrayList.
<T> T[]	toArray(T[] contents) Returns an array containing all elements contained in this ArrayList.
Object[]	toArray() Returns a new array containing all elements contained in this ArrayList.
void	trimToSize() Sets the capacity of this ArrayList to be the same as the size.

Protected Methods
void	removeRange(int start, int end) Removes the objects in the specified range from the start to the end, but not including the end index.

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Inherited Methods

From class java.util.AbstractList

void	add(int location, E object) Inserts the specified object into this List at the specified location.
boolean	add(E object) Adds the specified object at the end of this List.
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 answer if they are equal.
abstract E	get(int location) Returns the element at the specified location in this List.
int	hashCode() Returns an integer hash code for the receiver.
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 ListIterator on the elements of this List.
E	remove(int location) Removes the object at the specified location from this List.
void	removeRange(int start, int end) Removes the objects in the specified range from the start to the, but not including, end index.
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.

From class java.util.AbstractCollection

boolean	add(E object) If the specified element is not contained within this collection, and addition of this element succeeds, then true will be returned.
boolean	addAll(Collection<? extends E> collection) Adds the objects in the specified Collection to this Collection.
void	clear() Removes all the elements in this collection.
boolean	contains(Object object) Searches this Collection for the specified object.
boolean	containsAll(Collection<?> collection) Searches this Collection for all objects in the specified Collection.
boolean	isEmpty() Returns true if the collection has no element, otherwise false.
abstract Iterator<E>	iterator() Returns an Iterator on the elements of this Collection.
boolean	remove(Object object) Removes the first occurrence of the specified object from this Collection.
boolean	removeAll(Collection<?> collection) Removes all occurrences in this Collection of each object in the specified Collection.
boolean	retainAll(Collection<?> collection) Removes all objects from this Collection that are not contained in the specified Collection.
abstract int	size() Returns the number of elements in this Collection.
<T> T[]	toArray(T[] contents) Returns an array containing all elements contained in this Collection.
Object[]	toArray() Returns a new array containing all elements contained in this Collection.
String	toString() Returns the string representation of this Collection.

From class java.lang.Object

Object	clone() Returns a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.
void	finalize() Called by the virtual machine when there are no longer any (non-weak) references to the receiver.
final Class<? extends Object>	getClass() Returns the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode() Returns an integer hash code for the receiver.
final void	notify() Causes one thread which is `wait` ing on the receiver to be made ready to run.
final void	notifyAll() Causes all threads which are `wait` ing on the receiver to be made ready to run.
String	toString() Returns a string containing a concise, human-readable description of the receiver.
final void	wait(long time, int frac) Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final void	wait(long time) Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by `notify` or `notifyAll`) or the expiration of the timeout.
final void	wait() Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by `notify` or `notifyAll`).

From interface java.lang.Iterable

From interface java.util.Collection

abstract boolean	add(E object) Attempts to add `object` to the contents of this `Collection`.
abstract boolean	addAll(Collection<? extends E> collection) Attempts to add all of the objects contained in `collection` to the contents of this collection.
abstract void	clear() Removes all elements from this Collection, leaving it empty.
abstract boolean	contains(Object object) Searches this Collection for the specified object.
abstract boolean	containsAll(Collection<?> collection) Searches this Collection for all objects in the specified Collection.
abstract boolean	equals(Object object) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.
abstract int	hashCode() Returns an integer hash code for the receiver.
abstract boolean	isEmpty() Returns if this Collection has no elements, a size of zero.
abstract Iterator<E>	iterator() Returns an instance of Iterator that may be used to access the objects contained by this collection.
abstract boolean	remove(Object object) Removes the first occurrence of the specified object from this Collection.
abstract boolean	removeAll(Collection<?> collection) Removes all occurrences in this Collection of each object in the specified Collection.
abstract boolean	retainAll(Collection<?> collection) Removes all objects from this Collection that are not also found in the contents of `collection`.
abstract int	size() Returns a count of how many objects are contained by this collection.
abstract <T> T[]	toArray(T[] array) Returns an array containing all elements contained in this Collection.
abstract Object[]	toArray() Returns a new array containing all elements contained in this Collection.

From interface java.util.List

abstract void	add(int location, E object) Inserts the specified object into this Vector at the specified location.
abstract boolean	add(E object) Adds the specified object at the end of this List.
abstract boolean	addAll(int location, Collection<? extends E> collection) Inserts the objects in the specified Collection at the specified location in this List.
abstract boolean	addAll(Collection<? extends E> collection) Adds the objects in the specified Collection to the end of this List.
abstract void	clear() Removes all elements from this List, leaving it empty.
abstract boolean	contains(Object object) Searches this List for the specified object.
abstract boolean	containsAll(Collection<?> collection) Searches this List for all objects in the specified Collection.
abstract boolean	equals(Object object) Compares the argument to the receiver, and returns true if they represent the same object using a class specific comparison.
abstract E	get(int location) Returns the element at the specified location in this List.
abstract int	hashCode() Returns an integer hash code for the receiver.
abstract int	indexOf(Object object) Searches this List for the specified object and returns the index of the first occurrence.
abstract boolean	isEmpty() Returns if this List has no elements, a size of zero.
abstract Iterator<E>	iterator() Returns an Iterator on the elements of this List.
abstract int	lastIndexOf(Object object) Searches this List for the specified object and returns the index of the last occurrence.
abstract ListIterator<E>	listIterator() Returns a ListIterator on the elements of this List.
abstract ListIterator<E>	listIterator(int location) Returns a ListIterator on the elements of this List.
abstract E	remove(int location) Removes the object at the specified location from this List.
abstract boolean	remove(Object object) Removes the first occurrence of the specified object from this List.
abstract boolean	removeAll(Collection<?> collection) Removes all occurrences in this List of each object in the specified Collection.
abstract boolean	retainAll(Collection<?> collection) Removes all objects from this List that are not contained in the specified Collection.
abstract E	set(int location, E object) Replaces the element at the specified location in this List with the specified object.
abstract int	size() Returns the number of elements in this List.
abstract List<E>	subList(int start, int end) Returns a List of the specified portion of this List from the start index to one less than the end index.
abstract <T> T[]	toArray(T[] array) Returns an array containing all elements contained in this List.
abstract Object[]	toArray() Returns an array containing all elements contained in this List.

Public Constructors

public ArrayList ()

Constructs a new instance of ArrayList with zero capacity.

public ArrayList (int capacity)

Constructs a new instance of ArrayList with the specified capacity.

Parameters

capacity	the initial capacity of this ArrayList

public ArrayList (Collection<? extends E> collection)

Constructs a new instance of ArrayList containing the elements in the specified collection. The ArrayList will have an initial capacity which is 110% of the size of the collection. The order of the elements in this ArrayList is the order they are returned by the collection iterator.

Parameters

collection	the collection of elements to add

Public Methods

public void add (int location, E object)

Inserts the specified object into this ArrayList 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 ArrayList, the object is added at the end.

Parameters

location	the index at which to insert
object	the object to add

Throws

IndexOutOfBoundsException	when `location < 0 \|\| >= size()`

public boolean add (E object)

Adds the specified object at the end of this ArrayList.

Parameters

object	the object to add

Returns

true

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

Inserts the objects in the specified Collection at the specified location in this ArrayList. The objects are added in the order they are returned from the Collection iterator.

Parameters

location	the index at which to insert
collection	the Collection of objects

Returns

true if this ArrayList is modified, false otherwise

Throws

IndexOutOfBoundsException	when `location < 0 \|\| > size()`

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

Adds the objects in the specified Collection to this ArrayList.

Parameters

collection	the Collection of objects

Returns

true if this ArrayList is modified, false otherwise

public void clear ()

Removes all elements from this ArrayList, leaving it empty.

public Object clone ()

Returns a new ArrayList with the same elements, size and capacity as this ArrayList.

Returns

a shallow copy of this ArrayList

public boolean contains (Object object)

Searches this ArrayList for the specified object.

Parameters

object	the object to search for

Returns

true if object is an element of this ArrayList, false otherwise

public void ensureCapacity (int minimumCapacity)

Ensures that this ArrayList can hold the specified number of elements without growing.

Parameters

minimumCapacity	the minimum number of elements that this ArrayList will hold before growing

public E get (int location)

Returns the element at the specified location in this ArrayList.

Parameters

location	the index of the element to return

Returns

the element at the specified index

Throws

IndexOutOfBoundsException	when `location < 0 \|\| >= size()`

public int indexOf (Object object)

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

Parameters

object	the object to search for

Returns

the index of the first occurrence of the object

public boolean isEmpty ()

Returns if this ArrayList has no elements, a size of zero.

Returns

true if this ArrayList has no elements, false otherwise

public int lastIndexOf (Object object)

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

Parameters

object	the object to search for

Returns

the index of the last occurrence of the object

public E remove (int location)

Removes the object at the specified location from this ArrayList.

Parameters

location	the index of the object to remove

Returns

the removed object

Throws

IndexOutOfBoundsException	when `location < 0 \|\| >= size()`

public boolean remove (Object object)

Removes the first occurrence of the specified object from this Collection. This operation traverses over the collection, looking for the specified object. Once the object is found, the object will be removed from the collection using the iterator's remove method. This collection will throw an UnsupportedOperationException if the iterator returned does not implement remove method, and the specified object is in this collection.

Parameters

object	the object to remove

Returns

true if this Collection is modified, false otherwise

public E set (int location, E object)

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

Parameters

location	the index at which to put the specified object
object	the object to add

Returns

the previous element at the index

Throws

IndexOutOfBoundsException	when `location < 0 \|\| >= size()`

public int size ()

Returns the number of elements in this ArrayList.

Returns

the number of elements in this ArrayList

public 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.

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

public Object[] toArray ()

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

Returns

an array of the elements from this ArrayList

public void trimToSize ()

Sets the capacity of this ArrayList to be the same as the size.

Protected Methods

protected void removeRange (int start, int end)

Removes the objects in the specified range from the start to the end, but not including the end index.

Parameters

start	the index at which to start removing
end	the index one past the end of the range to remove

Throws

IndexOutOfBoundsException	when `start < 0, start > end` or `end > size()`

Jan	FEB	Mar
	17
2008	2009	2010

Interfaces

Classes

Enums

Exceptions

ArrayList

Class Overview

Summary

Public Constructors

public ArrayList ()

public ArrayList (int capacity)

Parameters

public ArrayList (Collection<? extends E> collection)

Parameters

Public Methods

public void add (int location, E object)

Parameters

Throws

public boolean add (E object)

Parameters

Returns

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

Parameters

Returns

Throws

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

Parameters

Returns

public void clear ()

See Also

public Object clone ()

Returns

See Also

public boolean contains (Object object)

Parameters

Returns

public void ensureCapacity (int minimumCapacity)

Parameters

public E get (int location)

Parameters

Returns

Throws

public int indexOf (Object object)

Parameters

Returns

public boolean isEmpty ()

Returns

See Also

public int lastIndexOf (Object object)

Parameters

Returns

public E remove (int location)

Parameters

Returns

Throws

public boolean remove (Object object)

Parameters

Returns

public E set (int location, E object)

Parameters

Returns

Throws

public int size ()

Returns

public T[] toArray (T[] contents)

Parameters

Returns

Throws

public Object[] toArray ()

Returns

public void trimToSize ()

See Also

Protected Methods

protected void removeRange (int start, int end)

Parameters

Throws