java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractList<E>
java.util.ArrayList<E>
public class ArrayList<E>
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 to 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 the 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.
This class is a member of the Java Collections Framework.
Collection, List, LinkedList, Vector, Serialized Form
ArrayList()
ArrayList(Collection<? extends E> c)
ArrayList(int initialCapacity)
boolean add(E e)
void add(int index, E element)
boolean addAll(Collection<? extends E> c)
boolean addAll(int index, Collection<? extends E> c)
void clear()
Object clone()
boolean contains(Object o)
void ensureCapacity(int minCapacity)
E get(int index)
int indexOf(Object o)
boolean isEmpty()
int lastIndexOf(Object o)
E remove(int index)
boolean remove(Object o)
protected void removeRange(int fromIndex, int toIndex)
E set(int index, E element)
int size()
Object[] toArray()
<T> T[] toArray(T[] a)
void trimToSize()
public ArrayList(int initialCapacity)
initialCapacity - the initial capacity of the list
IllegalArgumentException - if the specified initial capacity is negative
public ArrayList()
public ArrayList(Collection<? extends E> 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 Collection<E>
size in interface List<E>
size in class AbstractCollection<E>
public boolean isEmpty()
isEmpty in interface Collection<E>
isEmpty in interface List<E>
isEmpty in class AbstractCollection<E>
public boolean contains(Object o)
contains in interface Collection<E>
contains in interface List<E>
contains in class AbstractCollection<E>
o - element whose presence in this list is to be tested
public int indexOf(Object o)
indexOf in interface List<E>
indexOf in class AbstractList<E>
o - element to search for
public int lastIndexOf(Object o)
lastIndexOf in interface List<E>
lastIndexOf in class AbstractList<E>
o - element to search for
public Object clone()
clone in class Object
Cloneable
public Object[] toArray()
The returned array will be "safe" in that no references to it are maintained by this list. (In other words, this method must allocate a new array). The caller is thus free to modify the returned array.
This method acts as bridge between array-based and collection-based APIs.
toArray in interface Collection<E>
toArray in interface List<E>
toArray in class AbstractCollection<E>
Arrays.asList(Object[])
public <T> T[] toArray(T[] 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 Collection<E>
toArray in interface List<E>
toArray in class AbstractCollection<E>
a - 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 the specified array is not a supertype of the runtime type of every element in this list
NullPointerException - if the specified array is null
public E get(int index)
get in interface List<E>
get in class AbstractList<E>
index - index of the element to return
IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())
public E set(int index,
E element)
set in interface List<E>
set in class AbstractList<E>
index - index of the element to replace
element - element to be stored at the specified position
IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())
public boolean add(E e)
add in interface Collection<E>
add in interface List<E>
add in class AbstractList<E>
e - element to be appended to this list
Collection.add(E))
public void add(int index,
E element)
add in interface List<E>
add in class AbstractList<E>
index - index at which the specified element is to be inserted
element - element to be inserted
IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())
public E remove(int index)
remove in interface List<E>
remove in class AbstractList<E>
index - the index of the element to be removed
IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())
public boolean remove(Object o)
remove in interface Collection<E>
remove in interface List<E>
remove in class AbstractCollection<E>
o - element to be removed from this list, if present
public void clear()
clear in interface Collection<E>
clear in interface List<E>
clear in class AbstractList<E>
public boolean addAll(Collection<? extends E> c)
addAll in interface Collection<E>
addAll in interface List<E>
addAll in class AbstractCollection<E>
c - collection containing elements to be added to this list
NullPointerException - if the specified collection is null
AbstractCollection.add(Object)
public boolean addAll(int index,
Collection<? extends E> c)
addAll in interface List<E>
addAll in class AbstractList<E>
index - index at which to insert the first element from the specified collection
c - collection containing elements to be added to this list
IndexOutOfBoundsException - if the index is out of range (index < 0 || index > size())
NullPointerException - if the specified collection is null
protected void removeRange(int fromIndex,
int toIndex)
removeRange in class AbstractList<E>
fromIndex - index of first element to be removed
toIndex - index after last element to be removed
IndexOutOfBoundsException - if fromIndex or toIndex out of range (fromIndex < 0 || fromIndex >= size() || toIndex > size() || toIndex < fromIndex)
Copyright © 1993, 2015, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
Scripting on this page tracks web page traffic, but does not change the content in any way.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4