java.lang.Object | +--java.util.AbstractCollection | +--java.util.AbstractList | +--java.util.ArrayList
Untamed: Resizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, including null. In addition to implementing the List interface, this class provides methods to manipulate the size of the array that is used internally to store the list. (This class is roughly equivalent to Vector, except that it is unsynchronized.)
The size, isEmpty, get, set, iterator, and listIterator operations run in constant time. The add operation runs in amortized constant time, that is, adding n elements requires O(n) time. All of the other operations run in linear time (roughly speaking). The constant factor is low compared to that for the LinkedList implementation.
Each ArrayList instance has a capacity. The capacity is the size of the array used to store the elements in the list. It is always at least as large as the list size. As elements are added an ArrayList, its capacity grows automatically. The details of the growth policy are not specified beyond the fact that adding an element has constant amortized time cost.
An application can increase the capacity of an ArrayList instance before adding a large number of elements using the ensureCapacity operation. This may reduce the amount of incremental reallocation.
Note that this implementation is not synchronized. If multiple threads access an ArrayList instance concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements, or explicitly resizes the backing array; merely setting the value of an element is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the list. If no such object exists, the list should be "wrapped" using the Collections.synchronizedList method. This is best done at creation time, to prevent accidental unsynchronized access to the list:
List list = Collections.synchronizedList(new ArrayList(...));
The iterators returned by this class's iterator and listIterator methods are fail-fast: if list is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.
Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.
Collection,
List,
LinkedList,
Vector,
Collections.synchronizedList(List),
Serialized FormArrayList()
ArrayList(Collection c)
ArrayList(int initialCapacity)
void
add(int index,
Object element)
boolean
addAll(Collection c)
boolean
addAll(int index,
Collection c)
void
ensureCapacity(int minCapacity)
int
indexOf(Object elem)
int
lastIndexOf(Object elem)
private void
readObject(ObjectInputStream s)
protected void
removeRange(int fromIndex,
int toIndex)
Object
set(int index,
Object element)
Object[]
toArray()
Object[]
toArray(Object[] a)
void
trimToSize()
private void
writeObject(ObjectOutputStream s)
containsAll, equals, hashCode, iterator, listIterator, listIterator, remove, removeAll, retainAll, subList
private static final long serialVersionUID
private transient Object[] elementData
private int size
public ArrayList(int initialCapacity)
initialCapacity - the initial capacity of the list.public ArrayList()
public ArrayList(Collection c)
c - the collection whose elements are to be placed into this list.
NullPointerException - if the specified collection is null.public void trimToSize()
public void ensureCapacity(int minCapacity)
minCapacity - the desired minimum capacity.public int size()
size in interface Listsize in class AbstractCollectionpublic boolean isEmpty()
isEmpty in interface ListisEmpty in class AbstractCollectionpublic boolean contains(Object elem)
contains in interface Listcontains in class AbstractCollectionelem - element whose presence in this List is to be tested.
true if the specified element is present;
false otherwise.public int indexOf(Object elem)
indexOf in interface ListindexOf in class AbstractListelem - an object.
Object.equals(Object)public int lastIndexOf(Object elem)
lastIndexOf in interface ListlastIndexOf in class AbstractListelem - the desired element.
public Object clone()
java.lang.Cloneablepublic Object[] toArray()
toArray in interface ListtoArray in class AbstractCollectionArrays.asList(Object[])public Object[] toArray(Object[] a)
If the list fits in the specified array with room to spare (i.e., the array has more elements than the list), the element in the array immediately following the end of the collection is set to null. This is useful in determining the length of the list only if the caller knows that the list does not contain any null elements.
toArray in interface ListtoArray in class AbstractCollectiona - the array into which the elements of the list are to
be stored, if it is big enough; otherwise, a new array of the
same runtime type is allocated for this purpose.
ArrayStoreException - if the runtime type of a is not a supertype
of the runtime type of every element in this list.public Object get(int index)
get in interface Listget in class AbstractListindex - index of element to return.
IndexOutOfBoundsException - if index is out of range (index
< 0 || index >= size()).public Object set(int index, Object element)
set in interface Listset in class AbstractListindex - index of element to replace.element - element to be stored at the specified position.
IndexOutOfBoundsException - if index out of range
(index < 0 || index >= size()).public boolean add(Object o)
add in interface Listadd in class AbstractListo - element to be appended to this list.
public void add(int index, Object element)
add in interface Listadd in class AbstractListindex - index at which the specified element is to be inserted.element - element to be inserted.
IndexOutOfBoundsException - if index is out of range
(index < 0 || index > size()).public Object remove(int index)
remove in interface Listremove in class AbstractListindex - the index of the element to removed.
IndexOutOfBoundsException - if index out of range (index
< 0 || index >= size()).public void clear()
clear in interface Listclear in class AbstractListpublic boolean addAll(Collection c)
addAll in interface ListaddAll in class AbstractCollectionc - the elements to be inserted into this list.
IndexOutOfBoundsException - if index out of range (index
< 0 || index > size()).
NullPointerException - if the specified collection is null.List.add(Object)public boolean addAll(int index, Collection c)
addAll in interface ListaddAll in class AbstractListindex - index at which to insert first element
from the specified collection.c - elements to be inserted into this list.
IndexOutOfBoundsException - if index out of range (index
< 0 || index > size()).
NullPointerException - if the specified Collection is null.protected void removeRange(int fromIndex, int toIndex)
removeRange in class AbstractListfromIndex - index of first element to be removed.toIndex - index after last element to be removed.private void RangeCheck(int index)
private void writeObject(ObjectOutputStream s) throws IOException
private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException