public class ReferenceArrayList<K> extends AbstractReferenceList<K> implements RandomAccess, Cloneable, Serializable
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.
ArrayList,
Serialized FormAbstractReferenceList.ReferenceSubList<K>| Modifier and Type | Field and Description |
|---|---|
static int |
DEFAULT_INITIAL_CAPACITY
The initial default capacity of an array list.
|
| Constructor and Description |
|---|
ReferenceArrayList()
Creates a new array list with
DEFAULT_INITIAL_CAPACITY capacity. |
ReferenceArrayList(Collection<? extends K> c)
Creates a new array list and fills it with a given collection.
|
ReferenceArrayList(int capacity)
Creates a new array list with given capacity.
|
ReferenceArrayList(Iterator<? extends K> i)
Creates a new array list and fills it with the elements returned by an
iterator..
|
ReferenceArrayList(K[] a)
Creates a new array list and fills it with the elements of a given array.
|
ReferenceArrayList(K[] a,
int offset,
int length)
Creates a new array list and fills it with the elements of a given array.
|
ReferenceArrayList(ObjectIterator<? extends K> i)
Creates a new array list and fills it with the elements returned by a
type-specific iterator..
|
ReferenceArrayList(ReferenceCollection<? extends K> c)
Creates a new array list and fills it with a given type-specific
collection.
|
ReferenceArrayList(ReferenceList<? extends K> l)
Creates a new array list and fills it with a given type-specific list.
|
| Modifier and Type | Method and Description |
|---|---|
void |
add(int index,
K k)
Inserts the specified element at the specified position in this list
(optional operation).
|
boolean |
add(K k)
Ensures that this collection contains the specified element (optional
operation).
|
void |
addElements(int index,
K[] a,
int offset,
int length)
Adds elements to this type-specific list using optimized system calls.
|
void |
clear()
Removes all of the elements from this collection (optional operation).
|
ReferenceArrayList<K> |
clone()
Creates and returns a copy of this object.
|
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(ReferenceArrayList<K> l)
Compares this type-specific array list to another one.
|
K |
get(int index)
Returns the element at the specified position in this list.
|
void |
getElements(int from,
Object[] a,
int offset,
int length)
Copies element of this type-specific list into the given array using
optimized system calls.
|
int |
indexOf(Object k)
Returns the index of the first occurrence of the specified element
in this list, or -1 if this list does not contain the element.
|
boolean |
isEmpty()
Returns true if this collection contains no elements.
|
int |
lastIndexOf(Object k)
Returns the index of the last occurrence of the specified element
in this list, or -1 if this list does not contain the element.
|
ObjectListIterator<K> |
listIterator(int index)
Returns a type-specific list iterator on the list starting at a given
index.
|
K |
remove(int index)
Removes the element at the specified position in this list (optional
operation).
|
boolean |
remove(Object k)
Removes a single instance of the specified element from this
collection, if it is present (optional operation).
|
boolean |
removeAll(Collection<?> c)
Removes all of this collection's elements that are also contained in the
specified collection (optional operation).
|
void |
removeElements(int from,
int to)
Removes elements of this type-specific list using optimized system calls.
|
K |
set(int index,
K k)
Replaces the element at the specified position in this list with the
specified element (optional operation).
|
int |
size()
Returns the number of elements in this collection.
|
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> ReferenceArrayList<K> |
wrap(K[] a)
Wraps a given array into an array list.
|
static <K> ReferenceArrayList<K> |
wrap(K[] a,
int length)
Wraps a given array into an array list of given size.
|
addAll, addAll, addElements, contains, equals, hashCode, iterator, listIterator, peek, pop, push, subList, top, toStringcontainsAll, retainAll, toArray, toArraycontainsAll, replaceAll, retainAll, sort, spliterator, toArray, toArrayparallelStream, removeIf, streampublic static final int DEFAULT_INITIAL_CAPACITY
public ReferenceArrayList(int capacity)
capacity - the initial capacity of the array list (may be 0).public ReferenceArrayList()
DEFAULT_INITIAL_CAPACITY capacity.public ReferenceArrayList(Collection<? extends K> c)
c - a collection that will be used to fill the array list.public ReferenceArrayList(ReferenceCollection<? extends K> c)
c - a type-specific collection that will be used to fill the array
list.public ReferenceArrayList(ReferenceList<? extends K> l)
l - a type-specific list that will be used to fill the array list.public ReferenceArrayList(K[] a)
a - an array whose elements will be used to fill the array list.public ReferenceArrayList(K[] a, int offset, int length)
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.public ReferenceArrayList(Iterator<? extends K> i)
i - an iterator whose returned elements will fill the array list.public ReferenceArrayList(ObjectIterator<? extends K> i)
i - a type-specific iterator whose returned elements will fill the
array list.public K[] elements()
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[].
public static <K> ReferenceArrayList<K> wrap(K[] a, int length)
Note it is guaranteed that the type of the array returned by
elements() will be the same (see the comments in the class
documentation).
a - an array to wrap.length - the length of the resulting array list.public static <K> ReferenceArrayList<K> wrap(K[] a)
Note it is guaranteed that the type of the array returned by
elements() will be the same (see the comments in the class
documentation).
a - an array to wrap.public void ensureCapacity(int capacity)
capacity - the new minimum capacity for this array list.public void add(int index,
K k)
AbstractReferenceList
This implementation always throws an
UnsupportedOperationException.
public boolean add(K k)
AbstractReferenceListCollections that support this operation may place limitations on what elements may be added to this collection. In particular, some collections will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. Collection classes should clearly specify in their documentation any restrictions on what elements may be added.
If a collection refuses to add a particular element for any reason other than that it already contains the element, it must throw an exception (rather than returning false). This preserves the invariant that a collection always contains the specified element after this call returns.
This implementation always throws an UnsupportedOperationException.
This implementation delegates to the type-specific version of
List.add(int, Object).
add in interface Collection<K>add in interface List<K>add in class AbstractReferenceList<K>k - element whose presence in this collection is to be ensuredpublic K get(int index)
java.util.Listpublic int indexOf(Object k)
java.util.Listpublic int lastIndexOf(Object k)
java.util.ListlastIndexOf in interface List<K>lastIndexOf in class AbstractReferenceList<K>k - element to search forpublic K remove(int index)
AbstractReferenceList
This implementation always throws an
UnsupportedOperationException.
public boolean remove(Object k)
java.util.AbstractCollectionThis implementation iterates over the collection looking for the specified element. If it finds the element, it removes the element from the collection using the iterator's remove method.
Note that this implementation throws an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method and this collection contains the specified object.
remove in interface Collection<K>remove in interface List<K>remove in class AbstractCollection<K>k - element to be removed from this collection, if presentpublic K set(int index, K k)
AbstractReferenceList
This implementation always throws an
UnsupportedOperationException.
public void clear()
AbstractReferenceListThis implementation iterates over this collection, removing each element using the Iterator.remove operation. Most implementations will probably choose to override this method for efficiency.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method and this collection is non-empty.
This implementation delegates to AbstractReferenceList.removeElements(int, int).
clear in interface Collection<K>clear in interface List<K>clear in class AbstractReferenceList<K>public int size()
java.util.Collectionsize in interface Collection<K>size in interface List<K>size in class AbstractCollection<K>public void size(int size)
ReferenceList
If the specified size is smaller than the current size, the last elements
are discarded. Otherwise, they are filled with
0/null/false.
size in interface ReferenceList<K>size in class AbstractReferenceList<K>size - the new size.public boolean isEmpty()
java.util.AbstractCollectionThis implementation returns size() == 0.
public void trim()
ArrayList.trimToSize()public void trim(int n)
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.
n - the threshold for the trimming.public void getElements(int from,
Object[] a,
int offset,
int length)
getElements in interface ReferenceList<K>getElements in class AbstractReferenceList<K>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.public void removeElements(int from,
int to)
removeElements in interface ReferenceList<K>removeElements in class AbstractReferenceList<K>from - the start index (inclusive).to - the end index (exclusive).public void addElements(int index,
K[] a,
int offset,
int length)
addElements in interface ReferenceList<K>addElements in class AbstractReferenceList<K>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.public boolean removeAll(Collection<?> c)
java.util.AbstractCollectionThis implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection. If it's so contained, it's removed from this collection with the iterator's remove method.
Note that this implementation will throw an UnsupportedOperationException if the iterator returned by the iterator method does not implement the remove method and this collection contains one or more elements in common with the specified collection.
removeAll in interface Collection<K>removeAll in interface List<K>removeAll in class AbstractCollection<K>c - collection containing elements to be removed from this collectionAbstractCollection.remove(Object),
AbstractCollection.contains(Object)public ObjectListIterator<K> listIterator(int index)
AbstractReferenceListThis implementation is based on the random-access methods.
listIterator in interface ReferenceList<K>listIterator in interface List<K>listIterator in class AbstractReferenceList<K>index - index of the first element to be returned from the
list iterator (by a call to next)List.listIterator(int)public ReferenceArrayList<K> clone()
java.lang.Objectx, the expression:
will be true, and that the expression:x.clone() != x
will bex.clone().getClass() == x.getClass()
true, but these are not absolute requirements.
While it is typically the case that:
will bex.clone().equals(x)
true, this is not an absolute requirement.
By convention, the returned object should be obtained by calling
super.clone. If a class and all of its superclasses (except
Object) obey this convention, it will be the case that
x.clone().getClass() == x.getClass().
By convention, the object returned by this method should be independent
of this object (which is being cloned). To achieve this independence,
it may be necessary to modify one or more fields of the object returned
by super.clone before returning it. Typically, this means
copying any mutable objects that comprise the internal "deep structure"
of the object being cloned and replacing the references to these
objects with references to the copies. If a class contains only
primitive fields or references to immutable objects, then it is usually
the case that no fields in the object returned by super.clone
need to be modified.
The method clone for class Object performs a
specific cloning operation. First, if the class of this object does
not implement the interface Cloneable, then a
CloneNotSupportedException is thrown. Note that all arrays
are considered to implement the interface Cloneable and that
the return type of the clone method of an array type T[]
is T[] where T is any reference or primitive type.
Otherwise, this method creates a new instance of the class of this
object and initializes all its fields with exactly the contents of
the corresponding fields of this object, as if by assignment; the
contents of the fields are not themselves cloned. Thus, this method
performs a "shallow copy" of this object, not a "deep copy" operation.
The class Object does not itself implement the interface
Cloneable, so calling the clone method on an object
whose class is Object will result in throwing an
exception at run time.
public boolean equals(ReferenceArrayList<K> l)
This method exists only for sake of efficiency. The implementation inherited from the abstract implementation would already work.
l - a type-specific array list.