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 adding, removing, and replacing are supported. The elements can be any objects.

Summary

[Expand]
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 of 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 List.
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, the same size and the same capacity as this ArrayList.
boolean contains(Object object)
Searches this ArrayList for the specified object.
void ensureCapacity(int minimumCapacity)
Ensures that after this operation the ArrayList can hold the specified number of elements without further growing.
E get(int location)
Returns the element at the specified location in this list.
int indexOf(Object object)
Searches this list for the specified object and returns the index of the first occurrence.
boolean isEmpty()
Returns if this Collection contains no elements.
int lastIndexOf(Object object)
Searches this list 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 list.
boolean remove(Object object)
Removes one instance of the specified object from this Collection if one is contained (optional).
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 current 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.
[Expand]
Inherited Methods
From class java.util.AbstractList
From class java.util.AbstractCollection
From class java.lang.Object
From interface java.lang.Iterable
From interface java.util.Collection
From interface java.util.List

Public Constructors

public ArrayList ()

Since: API Level 1

Constructs a new instance of ArrayList with zero capacity.

public ArrayList (int capacity)

Since: API Level 1

Constructs a new instance of ArrayList with the specified capacity.

Parameters
capacity the initial capacity of this ArrayList.

public ArrayList (Collection<? extends E> collection)

Since: API Level 1

Constructs a new instance of ArrayList containing the elements of the specified collection. The initial size of the ArrayList will be 10% higher than the size of the specified collection.

Parameters
collection the collection of elements to add.

Public Methods

public void add (int location, E object)

Since: API Level 1

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 the object.
object the object to add.
Throws
IndexOutOfBoundsException when location < 0 || > size()

public boolean add (E object)

Since: API Level 1

Adds the specified object at the end of this ArrayList.

Parameters
object the object to add.
Returns
  • always true

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

Since: API Level 1

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.

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)

Since: API Level 1

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 ()

Since: API Level 1

Removes all elements from this ArrayList, leaving it empty.

See Also

public Object clone ()

Since: API Level 1

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

Returns
  • a shallow copy of this ArrayList
See Also

public boolean contains (Object object)

Since: API Level 1

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)

Since: API Level 1

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

Parameters
minimumCapacity the minimum capacity asked for.

public E get (int location)

Since: API Level 1

Returns the element at the specified location in this list.

Parameters
location the index of the element to return.
Returns
  • the element at the specified index.

public int indexOf (Object object)

Since: API Level 1

Searches this list 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, or -1 if it was not found.

public boolean isEmpty ()

Since: API Level 1

Returns if this Collection contains no elements. This implementation tests, whether size returns 0.

Returns
  • true if this Collection has no elements, false otherwise.

public int lastIndexOf (Object object)

Since: API Level 1

Searches this list 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, or -1 if the object was not found.

public E remove (int location)

Since: API Level 1

Removes the object at the specified location from this list.

Parameters
location the index of the object to remove.
Returns
  • the removed object.
Throws
IndexOutOfBoundsException when location < 0 || >= size()

public boolean remove (Object object)

Since: API Level 1

Removes one instance of the specified object from this Collection if one is contained (optional). This implementation iterates over this Collection and tests for each element e returned by the iterator, whether e is equal to the given object. If object != null then this test is performed using object.equals(e), otherwise using object == null. If an element equal to the given object is found, then the remove method is called on the iterator and true is returned, false otherwise. If the iterator does not support removing elements, an UnsupportedOperationException is thrown.

Parameters
object the object to remove.
Returns
  • true if this Collection is modified, false otherwise.

public E set (int location, E object)

Since: API Level 1

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 ()

Since: API Level 1

Returns the number of elements in this ArrayList.

Returns
  • the number of elements in this ArrayList.

public T[] toArray (T[] contents)

Since: API Level 1

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 ()

Since: API Level 1

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

Returns
  • an array of the elements from this ArrayList

public void trimToSize ()

Since: API Level 1

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

See Also

Protected Methods

protected void removeRange (int start, int end)

Since: API Level 1

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 after the end of the range to remove.
Throws
IndexOutOfBoundsException when start < 0, start > end or end > size()