it.unimi.dsi.fastutil.objects

Class ObjectArrayList<K>

java.lang.Object

java.util.AbstractCollection<K>

it.unimi.dsi.fastutil.objects.AbstractObjectCollection<K>

it.unimi.dsi.fastutil.objects.AbstractObjectList<K>

it.unimi.dsi.fastutil.objects.ObjectArrayList<K>

All Implemented Interfaces:

ObjectCollection<K>, ObjectIterable<K>, ObjectList<K>, Stack<K>, java.io.Serializable, java.lang.Cloneable, java.lang.Comparable<java.util.List<? extends K>>, java.lang.Iterable<K>, java.util.Collection<K>, java.util.List<K>, java.util.RandomAccess

public class ObjectArrayList<K>
extends AbstractObjectList<K>
implements java.util.RandomAccess, java.lang.Cloneable, java.io.Serializable

A type-specific array-based list; provides some additional methods that use polymorphism to avoid (un)boxing.

This class implements a lightweight, fast, open, optimized, reuse-oriented version of array-based lists. Instances of this class represent a list with an array that is enlarged as needed when new entries are created (by doubling the current length), but is never made smaller (even on a clear()). A family of trimming methods lets you control the size of the backing array; this is particularly useful if you reuse instances of this class. Range checks are equivalent to those of java.util's classes, but they are delayed as much as possible.

The backing array is exposed by the elements() method. If an instance of this class was created by wrapping, backing-array reallocations will be performed using reflection, so that elements() can return an array of the same type of the original array: the comments about efficiency made in ObjectArrays apply here. Moreover, you must take into consideration that assignment to an array not of type Object[] is slower due to type checking.

This class implements the bulk methods removeElements(), addElements() and getElements() using high-performance system calls (e.g., System.arraycopy() instead of expensive loops.

See Also:

ArrayList, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.objects.AbstractObjectList

AbstractObjectList.ObjectSubList<K>

Field Summary

Fields

Modifier and Type	Field and Description
protected K[]	a The backing array.
static int	DEFAULT_INITIAL_CAPACITY The initial default capacity of an array list.
protected int	size The current actual size of the list (never greater than the backing-array length).
protected boolean	wrapped Whether the backing array was passed to wrap().

Constructor Summary

Constructors

Modifier	Constructor and Description
	ObjectArrayList() Creates a new array list with DEFAULT_INITIAL_CAPACITY capacity.
	ObjectArrayList(java.util.Collection<? extends K> c) Creates a new array list and fills it with a given collection.
	ObjectArrayList(int capacity) Creates a new array list with given capacity.
	ObjectArrayList(java.util.Iterator<? extends K> i) Creates a new array list and fills it with the elements returned by an iterator..
	ObjectArrayList(K[] a) Creates a new array list and fills it with the elements of a given array.
protected	ObjectArrayList(K[] a, boolean dummy) Creates a new array list using a given array.
	ObjectArrayList(K[] a, int offset, int length) Creates a new array list and fills it with the elements of a given array.
	ObjectArrayList(ObjectCollection<? extends K> c) Creates a new array list and fills it with a given type-specific collection.
	ObjectArrayList(ObjectIterator<? extends K> i) Creates a new array list and fills it with the elements returned by a type-specific iterator..
	ObjectArrayList(ObjectList<? extends K> l) Creates a new array list and fills it with a given type-specific list.

Method Summary

Modifier and Type	Method and Description
void	add(int index, K k)
boolean	add(K k)
void	addElements(int index, K[] a, int offset, int length) Adds elements to this type-specific list using optimized system calls.
void	clear()
ObjectArrayList<K>	clone()
int	compareTo(ObjectArrayList<? extends K> l) Compares this array list to another array list.
K[]	elements() Returns the backing array of this list.
void	ensureCapacity(int capacity) Ensures that this array list can contain the given number of entries without resizing.
boolean	equals(ObjectArrayList<K> l) Compares this type-specific array list to another one.
K	get(int index)
void	getElements(int from, java.lang.Object[] a, int offset, int length) Copies element of this type-specific list into the given array using optimized system calls.
int	indexOf(java.lang.Object k)
boolean	isEmpty() Checks whether the stack is empty.
int	lastIndexOf(java.lang.Object k)
ObjectListIterator<K>	listIterator(int index) Returns a type-specific list iterator on the list starting at a given index.
boolean	rem(java.lang.Object k)
K	remove(int index)
boolean	remove(java.lang.Object o)
boolean	removeAll(java.util.Collection<?> c) Remove from this collection all elements in the given collection.
void	removeElements(int from, int to) Removes elements of this type-specific list using optimized system calls.
K	set(int index, K k)
int	size()
void	size(int size) Sets the size of this list.
void	trim() Trims this array list so that the capacity is equal to the size.
void	trim(int n) Trims the backing array if it is too large.
static <K> ObjectArrayList<K>	wrap(K[] a) Wraps a given array into an array list.
static <K> ObjectArrayList<K>	wrap(K[] a, int length) Wraps a given array into an array list of given size.

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObjectList

addAll, addAll, addElements, compareTo, contains, ensureIndex, ensureRestrictedIndex, equals, hashCode, iterator, listIterator, objectListIterator, objectListIterator, objectSubList, peek, pop, push, subList, top, toString

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObjectCollection

containsAll, objectIterator, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.List

containsAll, replaceAll, retainAll, sort, spliterator, toArray, toArray

Methods inherited from interface it.unimi.dsi.fastutil.objects.ObjectCollection

objectIterator, toArray

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

DEFAULT_INITIAL_CAPACITY

public static final int DEFAULT_INITIAL_CAPACITY

The initial default capacity of an array list.

See Also:

Constant Field Values

wrapped

protected final boolean wrapped

Whether the backing array was passed to wrap(). In this case, we must reallocate with the same type of array.

a

protected transient K[] a

The backing array.

size

protected int size

The current actual size of the list (never greater than the backing-array length).

Constructor Detail

ObjectArrayList

protected ObjectArrayList(K[] a,
                          boolean dummy)

Creates a new array list using a given array.

This constructor is only meant to be used by the wrapping methods.

Parameters:

a - the array that will be used to back this array list.

ObjectArrayList

public ObjectArrayList(int capacity)

Creates a new array list with given capacity.

Parameters:

capacity - the initial capacity of the array list (may be 0).

ObjectArrayList

public ObjectArrayList()

Creates a new array list with DEFAULT_INITIAL_CAPACITY capacity.

ObjectArrayList

public ObjectArrayList(java.util.Collection<? extends K> c)

Creates a new array list and fills it with a given collection.

Parameters:

c - a collection that will be used to fill the array list.

ObjectArrayList

public ObjectArrayList(ObjectCollection<? extends K> c)

Creates a new array list and fills it with a given type-specific collection.

Parameters:

c - a type-specific collection that will be used to fill the array list.

ObjectArrayList

public ObjectArrayList(ObjectList<? extends K> l)

Creates a new array list and fills it with a given type-specific list.

Parameters:

l - a type-specific list that will be used to fill the array list.

ObjectArrayList

public ObjectArrayList(K[] a)

Creates a new array list and fills it with the elements of a given array.

Parameters:

a - an array whose elements will be used to fill the array list.

ObjectArrayList

public ObjectArrayList(K[] a,
                       int offset,
                       int length)

Creates a new array list and fills it with the elements of a given array.

Parameters:

a - an array whose elements will be used to fill the array list.

offset - the first element to use.

length - the number of elements to use.

ObjectArrayList

public ObjectArrayList(java.util.Iterator<? extends K> i)

Creates a new array list and fills it with the elements returned by an iterator..

Parameters:

i - an iterator whose returned elements will fill the array list.

ObjectArrayList

public ObjectArrayList(ObjectIterator<? extends K> i)

Creates a new array list and fills it with the elements returned by a type-specific iterator..

Parameters:

i - a type-specific iterator whose returned elements will fill the array list.

Method Detail

elements

public K[] elements()

Returns the backing array of this list.

If this array list was created by wrapping a given array, it is guaranteed that the type of the returned array will be the same. Otherwise, the returned array will be of type Object[] (in spite of the declared return type).

Warning: This behaviour may cause (unfathomable) run-time errors if a method expects an array actually of type K[], but this methods returns an array of type Object[].

Returns:

the backing array.

wrap

public static <K> ObjectArrayList<K> wrap(K[] a,
                                          int length)

Wraps a given array into an array list of given size.

Note it is guaranteed that the type of the array returned by elements() will be the same (see the comments in the class documentation).

Parameters:

a - an array to wrap.

length - the length of the resulting array list.

Returns:

a new array list of the given size, wrapping the given array.

wrap

public static <K> ObjectArrayList<K> wrap(K[] a)

Wraps a given array into an array list.

Note it is guaranteed that the type of the array returned by elements() will be the same (see the comments in the class documentation).

Parameters:

a - an array to wrap.

Returns:

a new array list wrapping the given array.

ensureCapacity

public void ensureCapacity(int capacity)

Ensures that this array list can contain the given number of entries without resizing.

Parameters:

capacity - the new minimum capacity for this array list.

add

public void add(int index,
                K k)

Specified by:

add in interface java.util.List<K>

Overrides:

add in class AbstractObjectList<K>

add

public boolean add(K k)

Specified by:

add in interface java.util.Collection<K>

Specified by:

add in interface java.util.List<K>

Overrides:

add in class AbstractObjectList<K>

get

public K get(int index)

Specified by:

get in interface java.util.List<K>

indexOf

public int indexOf(java.lang.Object k)

Specified by:

indexOf in interface java.util.List<K>

Overrides:

indexOf in class AbstractObjectList<K>

lastIndexOf

public int lastIndexOf(java.lang.Object k)

Specified by:

lastIndexOf in interface java.util.List<K>

Overrides:

lastIndexOf in class AbstractObjectList<K>

remove

public K remove(int index)

Specified by:

remove in interface java.util.List<K>

Overrides:

remove in class AbstractObjectList<K>

rem

public boolean rem(java.lang.Object k)

remove

public boolean remove(java.lang.Object o)

Specified by:

remove in interface java.util.Collection<K>

Specified by:

remove in interface java.util.List<K>

Overrides:

remove in class java.util.AbstractCollection<K>

set

public K set(int index,
             K k)

Specified by:

set in interface java.util.List<K>

Overrides:

set in class AbstractObjectList<K>

clear

public void clear()

Specified by:

clear in interface java.util.Collection<K>

Specified by:

clear in interface java.util.List<K>

Overrides:

clear in class java.util.AbstractCollection<K>

size

public int size()

Specified by:

size in interface java.util.Collection<K>

Specified by:

size in interface java.util.List<K>

Specified by:

size in class java.util.AbstractCollection<K>

size

public void size(int size)

Description copied from interface: ObjectList

Sets the size of this list.

If the specified size is smaller than the current size, the last elements are discarded. Otherwise, they are filled with 0/null/ false.

Specified by:

size in interface ObjectList<K>

Overrides:

size in class AbstractObjectList<K>

Parameters:

size - the new size.

isEmpty

public boolean isEmpty()

Description copied from interface: Stack

Checks whether the stack is empty.

Specified by:

isEmpty in interface Stack<K>

Specified by:

isEmpty in interface java.util.Collection<K>

Specified by:

isEmpty in interface java.util.List<K>

Overrides:

isEmpty in class AbstractObjectCollection<K>

Returns:

true if the stack is empty.

trim

public void trim()

Trims this array list so that the capacity is equal to the size.

See Also:

ArrayList.trimToSize()

trim

public void trim(int n)

Trims the backing array if it is too large. If the current array length is smaller than or equal to n, this method does nothing. Otherwise, it trims the array length to the maximum between n and size().

This method is useful when reusing lists. Clearing a list leaves the array length untouched. If you are reusing a list many times, you can call this method with a typical size to avoid keeping around a very large array just because of a few large transient lists.

Parameters:

n - the threshold for the trimming.

getElements

public void getElements(int from,
                        java.lang.Object[] a,
                        int offset,
                        int length)

Copies element of this type-specific list into the given array using optimized system calls.

Specified by:

getElements in interface ObjectList<K>

Overrides:

getElements in class AbstractObjectList<K>

Parameters:

from - the start index (inclusive).

a - the destination array.

offset - the offset into the destination array where to store the first element copied.

length - the number of elements to be copied.

removeElements

public void removeElements(int from,
                           int to)

Removes elements of this type-specific list using optimized system calls.

Specified by:

removeElements in interface ObjectList<K>

Overrides:

removeElements in class AbstractObjectList<K>

Parameters:

from - the start index (inclusive).

to - the end index (exclusive).

addElements

public void addElements(int index,
                        K[] a,
                        int offset,
                        int length)

Adds elements to this type-specific list using optimized system calls.

Specified by:

addElements in interface ObjectList<K>

Overrides:

addElements in class AbstractObjectList<K>

Parameters:

index - the index at which to add elements.

a - the array containing the elements.

offset - the offset of the first element to add.

length - the number of elements to add.

removeAll

public boolean removeAll(java.util.Collection<?> c)

Description copied from class: AbstractObjectCollection

Remove from this collection all elements in the given collection. If the collection is an instance of this class, it uses faster iterators.

Specified by:

removeAll in interface java.util.Collection<K>

Specified by:

removeAll in interface java.util.List<K>

Overrides:

removeAll in class AbstractObjectCollection<K>

Parameters:

c - a collection.

Returns:

true if this collection changed as a result of the call.

listIterator

public ObjectListIterator<K> listIterator(int index)

Description copied from interface: ObjectList

Returns a type-specific list iterator on the list starting at a given index.

Specified by:

listIterator in interface ObjectList<K>

Specified by:

listIterator in interface java.util.List<K>

Overrides:

listIterator in class AbstractObjectList<K>

See Also:

List.listIterator(int)

clone

public ObjectArrayList<K> clone()

Overrides:

clone in class java.lang.Object

equals

public boolean equals(ObjectArrayList<K> l)

Compares this type-specific array list to another one.

This method exists only for sake of efficiency. The implementation inherited from the abstract implementation would already work.

Parameters:

l - a type-specific array list.

Returns:

true if the argument contains the same elements of this type-specific array list.

compareTo

public int compareTo(ObjectArrayList<? extends K> l)

Compares this array list to another array list.

This method exists only for sake of efficiency. The implementation inherited from the abstract implementation would already work.

Parameters:

l - an array list.

Returns:

a negative integer, zero, or a positive integer as this list is lexicographically less than, equal to, or greater than the argument.