AbstractList
abstract class AbstractList<E : Any!> : AbstractCollection<E>, MutableList<E>
kotlin.Any | ||
↳ | java.util.AbstractCollection<E> | |
↳ | java.util.AbstractList |
This class provides a skeletal implementation of the List
interface to minimize the effort required to implement this interface backed by a "random access" data store (such as an array). For sequential access data (such as a linked list), AbstractSequentialList
should be used in preference to this class.
To implement an unmodifiable list, the programmer needs only to extend this class and provide implementations for the get(int)
and size()
methods.
To implement a modifiable list, the programmer must additionally override the set(int, E)
method (which otherwise throws an UnsupportedOperationException
). If the list is variable-size the programmer must additionally override the add(int, E)
and remove(int)
methods.
The programmer should generally provide a void (no argument) and collection constructor, as per the recommendation in the Collection
interface specification.
Unlike the other abstract collection implementations, the programmer does not have to provide an iterator implementation; the iterator and list iterator are implemented by this class, on top of the "random access" methods: get(int)
, set(int, E)
, add(int, E)
and remove(int)
.
The documentation for each non-abstract method in this class describes its implementation in detail. Each of these methods may be overridden if the collection being implemented admits a more efficient implementation.
This class is a member of the Java Collections Framework.
Summary
Protected constructors | |
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Sole constructor. |
Public methods | |
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open Boolean |
add(element: E) Appends the specified element to the end of this list (optional operation). |
open Unit |
Inserts the specified element at the specified position in this list (optional operation). |
open Boolean |
addAll(index: Int, elements: Collection<E>) Inserts all of the elements in the specified collection into this list at the specified position (optional operation). |
open Unit |
clear() Removes all of the elements from this list (optional operation). |
open Boolean |
Compares the specified object with this list for equality. |
abstract E |
Returns the element at the specified position in this list. |
open Int |
hashCode() Returns the hash code value for this list. |
open Int |
indexOf(element: E?) Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element. |
open MutableIterator<E> |
iterator() Returns an iterator over the elements in this list in proper sequence. |
open Int |
lastIndexOf(element: E?) Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element. |
open MutableListIterator<E> |
Returns a list iterator over the elements in this list (in proper sequence). |
open MutableListIterator<E> |
listIterator(index: Int) Returns a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list. |
open E |
Removes the element at the specified position in this list (optional operation). |
open E |
Replaces the element at the specified position in this list with the specified element (optional operation). |
open MutableList<E> |
Returns a view of the portion of this list between the specified |
Protected methods | |
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open Unit |
removeRange(fromIndex: Int, toIndex: Int) Removes from this list all of the elements whose index is between |
Inherited functions | |
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Properties | |
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Int |
The number of times this list has been structurally modified. |
Inherited properties | |
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Protected constructors
AbstractList
protected AbstractList()
Sole constructor. (For invocation by subclass constructors, typically implicit.)
Public methods
add
open fun add(element: E): Boolean
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.
Parameters | |
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e |
element to be appended to this list |
Return | |
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Boolean |
true (as specified by Collection#add ) |
Exceptions | |
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java.lang.UnsupportedOperationException |
if the add operation is not supported by this list |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this list |
java.lang.NullPointerException |
if the specified element is null and this list does not permit null elements |
java.lang.IllegalArgumentException |
if some property of this element prevents it from being added to this list |
java.lang.IllegalStateException |
if the element cannot be added at this time due to insertion restrictions |
add
open fun add(
index: Int,
element: E
): Unit
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).
Parameters | |
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index |
Int: index at which the specified element is to be inserted |
element |
E: element to be inserted |
Exceptions | |
---|---|
java.lang.UnsupportedOperationException |
if the add operation is not supported by this list |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this list |
java.lang.NullPointerException |
if the specified element is null and this list does not permit null elements |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this list |
java.lang.IndexOutOfBoundsException |
if the index is out of range (index < 0 || index > size() ) |
addAll
open fun addAll(
index: Int,
elements: Collection<E>
): Boolean
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.)
Parameters | |
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index |
Int: index at which to insert the first element from the specified collection |
c |
collection containing elements to be added to this list |
Return | |
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Boolean |
true if this list changed as a result of the call |
Exceptions | |
---|---|
java.lang.UnsupportedOperationException |
if the addAll operation is not supported by this list |
java.lang.ClassCastException |
if the class of an element of the specified collection prevents it from being added to this list |
java.lang.NullPointerException |
if the specified collection contains one or more null elements and this list does not permit null elements, or if the specified collection is null |
java.lang.IllegalArgumentException |
if some property of an element of the specified collection prevents it from being added to this list |
java.lang.IndexOutOfBoundsException |
if the index is out of range (index < 0 || index > size() ) |
clear
open fun clear(): Unit
Removes all of the elements from this list (optional operation). The list will be empty after this call returns.
Exceptions | |
---|---|
java.lang.UnsupportedOperationException |
if the clear operation is not supported by this list |
equals
open fun equals(other: Any?): Boolean
Compares the specified object with this list for equality. Returns true
if and only if the specified object is also a list, both lists have the same size, and all corresponding pairs of elements in the two lists are equal. (Two elements e1
and e2
are equal if (e1==null ? e2==null : e1.equals(e2))
.) In other words, two lists are defined to be equal if they contain the same elements in the same order.
Parameters | |
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obj |
the reference object with which to compare. |
o |
the object to be compared for equality with this list |
Return | |
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Boolean |
true if the specified object is equal to this list |
get
abstract fun get(index: Int): E
Returns the element at the specified position in this list.
Parameters | |
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index |
Int: index of the element to return |
Return | |
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E |
the element at the specified position in this list |
Exceptions | |
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java.lang.IndexOutOfBoundsException |
if the index is out of range (index < 0 || index >= size() ) |
hashCode
open fun hashCode(): Int
Returns the hash code value for this list.
Return | |
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Int |
the hash code value for this list |
indexOf
open fun indexOf(element: E?): 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. More formally, returns the lowest index i
such that Objects.equals(o, get(i))
, or -1 if there is no such index.
Parameters | |
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o |
element to search for |
Return | |
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Int |
the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element |
Exceptions | |
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java.lang.ClassCastException |
if the type of the specified element is incompatible with this list (optional) |
java.lang.NullPointerException |
if the specified element is null and this list does not permit null elements (optional) |
iterator
open fun iterator(): MutableIterator<E>
Returns an iterator over the elements in this list in proper sequence.
Return | |
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MutableIterator<E> |
an iterator over the elements in this list in proper sequence |
lastIndexOf
open fun lastIndexOf(element: E?): 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. More formally, returns the highest index i
such that Objects.equals(o, get(i))
, or -1 if there is no such index.
Parameters | |
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o |
element to search for |
Return | |
---|---|
Int |
the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element |
Exceptions | |
---|---|
java.lang.ClassCastException |
if the type of the specified element is incompatible with this list (optional) |
java.lang.NullPointerException |
if the specified element is null and this list does not permit null elements (optional) |
listIterator
open fun listIterator(): MutableListIterator<E>
Returns a list iterator over the elements in this list (in proper sequence).
Return | |
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MutableListIterator<E> |
a list iterator over the elements in this list (in proper sequence) |
See Also
listIterator
open fun listIterator(index: Int): MutableListIterator<E>
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 to next
. An initial call to previous
would return the element with the specified index minus one.
Parameters | |
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index |
Int: index of the first element to be returned from the list iterator (by a call to next ) |
Return | |
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MutableListIterator<E> |
a list iterator over the elements in this list (in proper sequence), starting at the specified position in the list |
Exceptions | |
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java.lang.IndexOutOfBoundsException |
if the index is out of range (index < 0 || index > size() ) |
removeAt
open fun removeAt(index: Int): E
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.
Parameters | |
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index |
Int: the index of the element to be removed |
Return | |
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E |
the element previously at the specified position |
Exceptions | |
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java.lang.UnsupportedOperationException |
if the remove operation is not supported by this list |
java.lang.IndexOutOfBoundsException |
if the index is out of range (index < 0 || index >= size() ) |
set
open fun set(
index: Int,
element: E
): E
Replaces the element at the specified position in this list with the specified element (optional operation).
Parameters | |
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index |
Int: index of the element to replace |
element |
E: element to be stored at the specified position |
Return | |
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E |
the element previously at the specified position |
Exceptions | |
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java.lang.UnsupportedOperationException |
if the set operation is not supported by this list |
java.lang.ClassCastException |
if the class of the specified element prevents it from being added to this list |
java.lang.NullPointerException |
if the specified element is null and this list does not permit null elements |
java.lang.IllegalArgumentException |
if some property of the specified element prevents it from being added to this list |
java.lang.IndexOutOfBoundsException |
if the index is out of range (index < 0 || index >= size() ) |
subList
open fun subList(
fromIndex: Int,
toIndex: Int
): MutableList<E>
Returns a view of the portion of this list between the specified fromIndex
, inclusive, and toIndex
, exclusive. (If fromIndex
toIndex
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:
<code>list.subList(from, to).clear(); </code>Similar idioms may be constructed for
indexOf
and lastIndexOf
, and all of the algorithms in the Collections
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.)
Parameters | |
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fromIndex |
Int: low endpoint (inclusive) of the subList |
toIndex |
Int: high endpoint (exclusive) of the subList |
Return | |
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MutableList<E> |
a view of the specified range within this list |
Exceptions | |
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java.lang.IndexOutOfBoundsException |
if an endpoint index value is out of range (fromIndex < 0 || toIndex > size) |
java.lang.IllegalArgumentException |
if the endpoint indices are out of order (fromIndex > toIndex) |
Protected methods
removeRange
protected open fun removeRange(
fromIndex: Int,
toIndex: Int
): Unit
Removes from this list all of the elements whose index is between fromIndex
, inclusive, and toIndex
, exclusive. Shifts any succeeding elements to the left (reduces their index). This call shortens the list by (toIndex - fromIndex)
elements. (If toIndex==fromIndex
, this operation has no effect.)
This method is called by the clear
operation on this list and its subLists. Overriding this method to take advantage of the internals of the list implementation can substantially improve the performance of the clear
operation on this list and its subLists.
Parameters | |
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fromIndex |
Int: index of first element to be removed |
toIndex |
Int: index after last element to be removed |
Properties
modCount
protected var modCount: Int
The number of times this list has been structurally modified. Structural modifications are those that change the size of the list, or otherwise perturb it in such a fashion that iterations in progress may yield incorrect results.
This field is used by the iterator and list iterator implementation returned by the iterator
and listIterator
methods. If the value of this field changes unexpectedly, the iterator (or list iterator) will throw a ConcurrentModificationException
in response to the next
, remove
, previous
, set
or add
operations. This provides fail-fast behavior, rather than non-deterministic behavior in the face of concurrent modification during iteration.
Use of this field by subclasses is optional. If a subclass wishes to provide fail-fast iterators (and list iterators), then it merely has to increment this field in its add(int, E)
and remove(int)
methods (and any other methods that it overrides that result in structural modifications to the list). A single call to add(int, E)
or remove(int)
must add no more than one to this field, or the iterators (and list iterators) will throw bogus ConcurrentModificationExceptions
. If an implementation does not wish to provide fail-fast iterators, this field may be ignored.