Class WeakList<E>
- All Implemented Interfaces:
Iterable<E>
,Collection<E>
,List<E>
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
Inserts the specified element at the specified position in this list (optional operation).boolean
Appends the specified element to the end of this list (optional operation).boolean
Adds the given element to the end of this list.boolean
add
(WeakReference<E> e) boolean
addAll
(int index, @NotNull Collection<? extends E> c) Inserts all of the elements in the specified collection into this list at the specified position (optional operation).boolean
addAll
(@NotNull Collection<? extends E> c) Appends 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 (optional operation).void
clear()
Removes all of the elements from this list (optional operation).boolean
Returnstrue
if this list contains the specified element.boolean
containsAll
(@NotNull Collection<?> c) Returnstrue
if this list contains all of the elements of the specified collection.get
(int index) Returns the element at the specified position in this list.int
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()
Returnstrue
if this list contains no elements.iterator()
Returns an iterator over the elements in this list in proper sequence.int
Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.@NotNull ListIterator<E>
Returns a list iterator over the elements in this list (in proper sequence).@NotNull ListIterator<E>
listIterator
(int index) Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list.remove
(int index) Removes the element at the specified position in this list (optional operation).boolean
Removes the first occurrence of the specified element from this list, if it is present (optional operation).boolean
removeAll
(@NotNull Collection<?> c) Removes from this list all of its elements that are contained in the specified collection (optional operation).boolean
retainAll
(@NotNull Collection<?> c) Retains only the elements in this list that are contained in the specified collection (optional operation).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 list.subList
(int fromIndex, int toIndex) Returns a view of the portion of this list between the specifiedfromIndex
, inclusive, andtoIndex
, exclusive.@NotNull Object[]
toArray()
Returns an array containing all of the elements in this list in proper sequence (from first to last element).<T> @NotNull T[]
toArray
(@NotNull T[] a) Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface java.util.Collection
parallelStream, removeIf, stream, toArray
Methods inherited from interface java.util.List
equals, hashCode, replaceAll, sort, spliterator
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Constructor Details
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WeakList
public WeakList()
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Method Details
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size
public int size()Returns the number of elements in this list. If this list contains more thanInteger.MAX_VALUE
elements, returnsInteger.MAX_VALUE
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isEmpty
public boolean isEmpty()Returnstrue
if this list contains no elements. -
contains
Returnstrue
if this list contains the specified element. More formally, returnstrue
if and only if this list contains at least one elemente
such thatObjects.equals(o, e)
.- Specified by:
contains
in interfaceCollection<E>
- Specified by:
contains
in interfaceList<E>
- Parameters:
o
- element whose presence in this list is to be tested- Returns:
true
if this list contains the specified element- Throws:
ClassCastException
- if the type of the specified element is incompatible with this list (optional)NullPointerException
- if the specified element is null and this list does not permit null elements (optional)
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iterator
Returns an iterator over the elements in this list in proper sequence. -
toArray
Returns an array containing all of the elements in this list in proper sequence (from first to last element).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 even if this list is backed by an array). The caller is thus free to modify the returned array.
This method acts as bridge between array-based and collection-based APIs.
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toArray
@NotNull public <T> @NotNull T[] toArray(@NotNull @NotNull T[] a) Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array. If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.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 list 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.)Like the
toArray()
method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs.Suppose
x
is a list known to contain only strings. The following code can be used to dump the list into a newly allocated array ofString
:String[] y = x.toArray(new String[0]);
Note that
toArray(new Object[0])
is identical in function totoArray()
.- Specified by:
toArray
in interfaceCollection<E>
- Specified by:
toArray
in interfaceList<E>
- Parameters:
a
- the array into which the elements of this list are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose.- Returns:
- an array containing the elements of this list
- Throws:
ArrayStoreException
- if the runtime type of the specified array is not a supertype of the runtime type of every element in this listNullPointerException
- if the specified array is null
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add
Appends the specified element to the end of this list (optional operation).Lists that support this operation may place limitations on what elements may be added to this list. In particular, some lists will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. List classes should clearly specify in their documentation any restrictions on what elements may be added.
- Specified by:
add
in interfaceCollection<E>
- Specified by:
add
in interfaceList<E>
- Parameters:
e
- element to be appended to this list- Returns:
true
(as specified byCollection.add(E)
)- Throws:
UnsupportedOperationException
- if theadd
operation is not supported by this listClassCastException
- if the class of the specified element prevents it from being added to this listNullPointerException
- if the specified element is null and this list does not permit null elementsIllegalArgumentException
- if some property of this element prevents it from being added to this list
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add
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add
Adds the given element to the end of this list.- Parameters:
e
- The element, already boxed in a weak reference.- Returns:
true
(as specified byCollection.add(E)
)
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remove
Removes the first occurrence of the specified element from this list, if it is present (optional operation). If this list does not contain the element, it is unchanged. More formally, removes the element with the lowest indexi
such thatObjects.equals(o, get(i))
(if such an element exists). Returnstrue
if this list contained the specified element (or equivalently, if this list changed as a result of the call).- Specified by:
remove
in interfaceCollection<E>
- Specified by:
remove
in interfaceList<E>
- Parameters:
o
- element to be removed from this list, if present- Returns:
true
if this list contained the specified element- Throws:
ClassCastException
- if the type of the specified element is incompatible with this list (optional)NullPointerException
- if the specified element is null and this list does not permit null elements (optional)UnsupportedOperationException
- if theremove
operation is not supported by this list
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containsAll
Returnstrue
if this list contains all of the elements of the specified collection.- Specified by:
containsAll
in interfaceCollection<E>
- Specified by:
containsAll
in interfaceList<E>
- Parameters:
c
- collection to be checked for containment in this list- Returns:
true
if this list contains all of the elements of the specified collection- Throws:
ClassCastException
- if the types of one or more elements in the specified collection are incompatible with this list (optional)NullPointerException
- if the specified collection contains one or more null elements and this list does not permit null elements (optional), or if the specified collection is null- See Also:
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addAll
Appends 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 (optional operation). The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)- Specified by:
addAll
in interfaceCollection<E>
- Specified by:
addAll
in interfaceList<E>
- Parameters:
c
- collection containing elements to be added to this list- Returns:
true
if this list changed as a result of the call- Throws:
UnsupportedOperationException
- if theaddAll
operation is not supported by this listClassCastException
- if the class of an element of the specified collection prevents it from being added to this listNullPointerException
- if the specified collection contains one or more null elements and this list does not permit null elements, or if the specified collection is nullIllegalArgumentException
- if some property of an element of the specified collection prevents it from being added to this list- See Also:
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addAll
Inserts all of the elements in the specified collection into this list at the specified position (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (increases their indices). The new elements will appear in this list in the order that they are returned by the specified collection's iterator. The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (Note that this will occur if the specified collection is this list, and it's nonempty.)- Specified by:
addAll
in interfaceList<E>
- Parameters:
index
- index at which to insert the first element from the specified collectionc
- collection containing elements to be added to this list- Returns:
true
if this list changed as a result of the call- Throws:
UnsupportedOperationException
- if theaddAll
operation is not supported by this listClassCastException
- if the class of an element of the specified collection prevents it from being added to this listNullPointerException
- if the specified collection contains one or more null elements and this list does not permit null elements, or if the specified collection is nullIllegalArgumentException
- if some property of an element of the specified collection prevents it from being added to this listIndexOutOfBoundsException
- if the index is out of range (index < 0 || index > size()
)
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removeAll
Removes from this list all of its elements that are contained in the specified collection (optional operation).- Specified by:
removeAll
in interfaceCollection<E>
- Specified by:
removeAll
in interfaceList<E>
- Parameters:
c
- collection containing elements to be removed from this list- Returns:
true
if this list changed as a result of the call- Throws:
UnsupportedOperationException
- if theremoveAll
operation is not supported by this listClassCastException
- if the class of an element of this list is incompatible with the specified collection (optional)NullPointerException
- if this list contains a null element and the specified collection does not permit null elements (optional), or if the specified collection is null- See Also:
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retainAll
Retains only the elements in this list that are contained in the specified collection (optional operation). In other words, removes from this list all of its elements that are not contained in the specified collection.- Specified by:
retainAll
in interfaceCollection<E>
- Specified by:
retainAll
in interfaceList<E>
- Parameters:
c
- collection containing elements to be retained in this list- Returns:
true
if this list changed as a result of the call- Throws:
UnsupportedOperationException
- if theretainAll
operation is not supported by this listClassCastException
- if the class of an element of this list is incompatible with the specified collection (optional)NullPointerException
- if this list contains a null element and the specified collection does not permit null elements (optional), or if the specified collection is null- See Also:
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clear
public void clear()Removes all of the elements from this list (optional operation). The list will be empty after this call returns.- Specified by:
clear
in interfaceCollection<E>
- Specified by:
clear
in interfaceList<E>
- Throws:
UnsupportedOperationException
- if theclear
operation is not supported by this list
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get
Returns the element at the specified position in this list.- Specified by:
get
in interfaceList<E>
- Parameters:
index
- index of the element to return- Returns:
- the element at the specified position in this list
- Throws:
IndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)
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set
Replaces the element at the specified position in this list with the specified element (optional operation).- Specified by:
set
in interfaceList<E>
- Parameters:
index
- index of the element to replaceelement
- element to be stored at the specified position- Returns:
- the element previously at the specified position
- Throws:
UnsupportedOperationException
- if theset
operation is not supported by this listClassCastException
- if the class of the specified element prevents it from being added to this listNullPointerException
- if the specified element is null and this list does not permit null elementsIllegalArgumentException
- if some property of the specified element prevents it from being added to this listIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)
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add
Inserts the specified element at the specified position in this list (optional operation). Shifts the element currently at that position (if any) and any subsequent elements to the right (adds one to their indices).- Specified by:
add
in interfaceList<E>
- Parameters:
index
- index at which the specified element is to be insertedelement
- element to be inserted- Throws:
UnsupportedOperationException
- if theadd
operation is not supported by this listClassCastException
- if the class of the specified element prevents it from being added to this listNullPointerException
- if the specified element is null and this list does not permit null elementsIllegalArgumentException
- if some property of the specified element prevents it from being added to this listIndexOutOfBoundsException
- if the index is out of range (index < 0 || index > size()
)
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remove
Removes the element at the specified position in this list (optional operation). Shifts any subsequent elements to the left (subtracts one from their indices). Returns the element that was removed from the list.- Specified by:
remove
in interfaceList<E>
- Parameters:
index
- the index of the element to be removed- Returns:
- the element previously at the specified position
- Throws:
UnsupportedOperationException
- if theremove
operation is not supported by this listIndexOutOfBoundsException
- if the index is out of range (index < 0 || index >= size()
)
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indexOf
Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the lowest indexi
such thatObjects.equals(o, get(i))
, or -1 if there is no such index.- Specified by:
indexOf
in interfaceList<E>
- Parameters:
o
- element to search for- Returns:
- the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element
- Throws:
ClassCastException
- if the type of the specified element is incompatible with this list (optional)NullPointerException
- if the specified element is null and this list does not permit null elements (optional)
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lastIndexOf
Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element. More formally, returns the highest indexi
such thatObjects.equals(o, get(i))
, or -1 if there is no such index.- Specified by:
lastIndexOf
in interfaceList<E>
- Parameters:
o
- element to search for- Returns:
- the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element
- Throws:
ClassCastException
- if the type of the specified element is incompatible with this list (optional)NullPointerException
- if the specified element is null and this list does not permit null elements (optional)
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listIterator
Returns a list iterator over the elements in this list (in proper sequence).- Specified by:
listIterator
in interfaceList<E>
- Returns:
- a list iterator over the elements in this list (in proper sequence)
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listIterator
Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list. The specified index indicates the first element that would be returned by an initial call tonext
. An initial call toprevious
would return the element with the specified index minus one.- Specified by:
listIterator
in interfaceList<E>
- Parameters:
index
- index of the first element to be returned from the list iterator (by a call tonext
)- Returns:
- a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list
- Throws:
IndexOutOfBoundsException
- if the index is out of range (index < 0 || index > size()
)
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subList
Returns a view of the portion of this list between the specifiedfromIndex
, inclusive, andtoIndex
, exclusive. (IffromIndex
andtoIndex
are equal, the returned list is empty.) The returned list is backed by this list, so non-structural changes in the returned list are reflected in this list, and vice-versa. The returned list supports all of the optional list operations supported by this list.This method eliminates the need for explicit range operations (of the sort that commonly exist for arrays). Any operation that expects a list can be used as a range operation by passing a subList view instead of a whole list. For example, the following idiom removes a range of elements from a list:
Similar idioms may be constructed forlist.subList(from, to).clear();
indexOf
andlastIndexOf
, and all of the algorithms in theCollections
class can be applied to a subList.The semantics of the list returned by this method become undefined if the backing list (i.e., this list) is structurally modified in any way other than via the returned list. (Structural modifications are those that change the size of this list, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results.)
- Specified by:
subList
in interfaceList<E>
- Parameters:
fromIndex
- low endpoint (inclusive) of the subListtoIndex
- high endpoint (exclusive) of the subList- Returns:
- a view of the specified range within this list
- Throws:
IndexOutOfBoundsException
- for an illegal endpoint index value (fromIndex < 0 || toIndex > size || fromIndex > toIndex
)
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