public class FastArrayList extends ArrayList
A customized implementation of java.util.ArrayList designed
to operate in a multithreaded environment where the large majority of
method calls are read-only, instead of structural changes. When operating
in "fast" mode, read calls are non-synchronized and write calls perform the
following steps:
When first created, objects of this class default to "slow" mode, where
all accesses of any type are synchronized but no cloning takes place. This
is appropriate for initially populating the collection, followed by a switch
to "fast" mode (by calling setFast(true)) after initialization
is complete.
NOTE: If you are creating and accessing an
ArrayList only within a single thread, you should use
java.util.ArrayList directly (with no synchronization), for
maximum performance.
NOTE: This class is not cross-platform. Using it may cause unexpected failures on some architectures. It suffers from the same problems as the double-checked locking idiom. In particular, the instruction that clones the internal collection and the instruction that sets the internal reference to the clone can be executed or perceived out-of-order. This means that any read operation might fail unexpectedly, as it may be reading the state of the internal collection before the internal collection is fully formed. For more information on the double-checked locking idiom, see the Double-Checked Locking Idiom Is Broken Declaration.
| Modifier and Type | Field and Description |
|---|---|
protected boolean |
fast
Are we operating in "fast" mode?
|
protected ArrayList |
list
The underlying list we are managing.
|
modCount| Constructor and Description |
|---|
FastArrayList()
Construct a an empty list.
|
FastArrayList(Collection collection)
Construct a list containing the elements of the specified collection,
in the order they are returned by the collection's iterator.
|
FastArrayList(int capacity)
Construct an empty list with the specified capacity.
|
| Modifier and Type | Method and Description |
|---|---|
void |
add(int index,
Object element)
Insert the specified element at the specified position in this list,
and shift all remaining elements up one position.
|
boolean |
add(Object element)
Appends the specified element to the end of this list.
|
boolean |
addAll(Collection collection)
Append all of the elements in the specified Collection to the end
of this list, in the order that they are returned by the specified
Collection's Iterator.
|
boolean |
addAll(int index,
Collection collection)
Insert all of the elements in the specified Collection at the specified
position in this list, and shift any previous elements upwards as
needed.
|
void |
clear()
Remove all of the elements from this list.
|
Object |
clone()
Return a shallow copy of this
FastArrayList instance. |
boolean |
contains(Object element)
Return
true if this list contains the specified element. |
boolean |
containsAll(Collection collection)
Return
true if this list contains all of the elements
in the specified Collection. |
void |
ensureCapacity(int capacity)
Increase the capacity of this
ArrayList instance, if
necessary, to ensure that it can hold at least the number of elements
specified by the minimum capacity argument. |
boolean |
equals(Object o)
Compare the specified object with this list for equality.
|
Object |
get(int index)
Return the element at the specified position in the list.
|
boolean |
getFast()
Returns true if this list is operating in fast mode.
|
int |
hashCode()
Return the hash code value for this list.
|
int |
indexOf(Object element)
Search for the first occurrence of the given argument, testing
for equality using the
equals() method, and return
the corresponding index, or -1 if the object is not found. |
boolean |
isEmpty()
Test if this list has no elements.
|
Iterator |
iterator()
Return an iterator over the elements in this list in proper sequence.
|
int |
lastIndexOf(Object element)
Search for the last occurrence of the given argument, testing
for equality using the
equals() method, and return
the corresponding index, or -1 if the object is not found. |
ListIterator |
listIterator()
Return an iterator of the elements of this list, in proper sequence.
|
ListIterator |
listIterator(int index)
Return an iterator of the elements of this list, in proper sequence,
starting at the specified position.
|
Object |
remove(int index)
Remove the element at the specified position in the list, and shift
any subsequent elements down one position.
|
boolean |
remove(Object element)
Remove the first occurrence of the specified element from the list,
and shift any subsequent elements down one position.
|
boolean |
removeAll(Collection collection)
Remove from this collection all of its elements that are contained
in the specified collection.
|
boolean |
retainAll(Collection collection)
Remove from this collection all of its elements except those that are
contained in the specified collection.
|
Object |
set(int index,
Object element)
Replace the element at the specified position in this list with
the specified element.
|
void |
setFast(boolean fast)
Sets whether this list will operate in fast mode.
|
int |
size()
Return the number of elements in this list.
|
List |
subList(int fromIndex,
int toIndex)
Return a view of the portion of this list between fromIndex
(inclusive) and toIndex (exclusive).
|
Object[] |
toArray()
Return an array containing all of the elements in this list in the
correct order.
|
Object[] |
toArray(Object[] array)
Return an array containing all of the elements in this list in the
correct order.
|
String |
toString()
Return a String representation of this object.
|
void |
trimToSize()
Trim the capacity of this
ArrayList instance to be the
list's current size. |
removeRangeprotected ArrayList list
protected boolean fast
public FastArrayList()
public FastArrayList(int capacity)
capacity - The initial capacity of the empty listpublic FastArrayList(Collection collection)
collection - The collection whose elements initialize the contents
of this listpublic boolean getFast()
public void setFast(boolean fast)
fast - true if the list should operate in fast modepublic boolean add(Object element)
public void add(int index,
Object element)
add in interface Listadd in class ArrayListindex - Index at which to insert this elementelement - The element to be insertedIndexOutOfBoundsException - if the index is out of rangepublic boolean addAll(Collection collection)
public boolean addAll(int index,
Collection collection)
addAll in interface ListaddAll in class ArrayListindex - Index at which insertion takes placecollection - The collection to be addedIndexOutOfBoundsException - if the index is out of rangepublic void clear()
clear in interface Collectionclear in interface Listclear in class ArrayListUnsupportedOperationException - if clear()
is not supported by this listpublic Object clone()
FastArrayList instance.
The elements themselves are not copied.public boolean contains(Object element)
true if this list contains the specified element.public boolean containsAll(Collection collection)
true if this list contains all of the elements
in the specified Collection.containsAll in interface CollectioncontainsAll in interface ListcontainsAll in class AbstractCollectioncollection - Collection whose elements are to be checkedpublic void ensureCapacity(int capacity)
ArrayList instance, if
necessary, to ensure that it can hold at least the number of elements
specified by the minimum capacity argument.ensureCapacity in class ArrayListcapacity - The new minimum capacitypublic boolean equals(Object o)
List.equals method.equals in interface Collectionequals in interface Listequals in class AbstractListo - Object to be compared to this listpublic Object get(int index)
get in interface Listget in class ArrayListindex - The index of the element to returnIndexOutOfBoundsException - if the index is out of rangepublic int hashCode()
List.hashCode method.hashCode in interface CollectionhashCode in interface ListhashCode in class AbstractListpublic int indexOf(Object element)
equals() method, and return
the corresponding index, or -1 if the object is not found.public boolean isEmpty()
public Iterator iterator()
Thread safety
The iterator returned is thread-safe ONLY in FAST mode.
In slow mode there is no way to synchronize, or make the iterator thread-safe.
In fast mode iteration and modification may occur in parallel on different threads, however there is a restriction. Modification must be EITHER via the Iterator interface methods OR the List interface. If a mixture of modification methods is used a ConcurrentModificationException is thrown from the iterator modification method. If the List modification methods are used the changes are NOT visible in the iterator (it shows the list contents at the time the iterator was created).
public int lastIndexOf(Object element)
equals() method, and return
the corresponding index, or -1 if the object is not found.lastIndexOf in interface ListlastIndexOf in class ArrayListelement - The element to search forpublic ListIterator listIterator()
Thread safety
The iterator returned is thread-safe ONLY in FAST mode.
In slow mode there is no way to synchronize, or make the iterator thread-safe.
In fast mode iteration and modification may occur in parallel on different threads, however there is a restriction. Modification must be EITHER via the Iterator interface methods OR the List interface. If a mixture of modification methods is used a ConcurrentModificationException is thrown from the iterator modification method. If the List modification methods are used the changes are NOT visible in the iterator (it shows the list contents at the time the iterator was created).
listIterator in interface ListlistIterator in class ArrayListpublic ListIterator listIterator(int index)
Thread safety
The iterator returned is thread-safe ONLY in FAST mode.
In slow mode there is no way to synchronize, or make the iterator thread-safe.
In fast mode iteration and modification may occur in parallel on different threads, however there is a restriction. Modification must be EITHER via the Iterator interface methods OR the List interface. If a mixture of modification methods is used a ConcurrentModificationException is thrown from the iterator modification method. If the List modification methods are used the changes are NOT visible in the iterator (it shows the list contents at the time the iterator was created).
listIterator in interface ListlistIterator in class ArrayListindex - The starting position of the iterator to returnIndexOutOfBoundsException - if the index is out of rangepublic Object remove(int index)
remove in interface Listremove in class ArrayListindex - Index of the element to be removedIndexOutOfBoundsException - if the index is out of rangepublic boolean remove(Object element)
public boolean removeAll(Collection collection)
removeAll in interface CollectionremoveAll in interface ListremoveAll in class ArrayListcollection - Collection containing elements to be removedUnsupportedOperationException - if this optional operation
is not supported by this listpublic boolean retainAll(Collection collection)
retainAll in interface CollectionretainAll in interface ListretainAll in class ArrayListcollection - Collection containing elements to be retainedUnsupportedOperationException - if this optional operation
is not supported by this listpublic Object set(int index, Object element)
set in interface Listset in class ArrayListindex - Index of the element to replaceelement - The new element to be storedIndexOutOfBoundsException - if the index is out of rangepublic int size()
public List subList(int fromIndex, int toIndex)
subList in interface ListsubList in class ArrayListfromIndex - The starting index of the sublist viewtoIndex - The index after the end of the sublist viewIndexOutOfBoundsException - if an index is out of rangepublic Object[] toArray()
public Object[] toArray(Object[] array)
toArray in interface CollectiontoArray in interface ListtoArray in class ArrayListarray - Array defining the element type of the returned listArrayStoreException - if the runtime type of array
is not a supertype of the runtime type of every element in this listpublic String toString()
toString in class AbstractCollectionpublic void trimToSize()
ArrayList instance to be the
list's current size. An application can use this operation to minimize
the storage of an ArrayList instance.trimToSize in class ArrayListCopyright © 2001–2015 The Apache Software Foundation. All rights reserved.