java.lang.Object | |
↳ | android.support.v4.util.LongSparseArray<E> |
SparseArray mapping longs to Objects, a version of the platform's
LongSparseArray
that can be used on older versions of the
platform. Unlike a normal array of Objects,
there can be gaps in the indices. It is intended to be more memory efficient
than using a HashMap to map Longs to Objects, both because it avoids
auto-boxing keys and its data structure doesn't rely on an extra entry object
for each mapping.
Note that this container keeps its mappings in an array data structure, using a binary search to find keys. The implementation is not intended to be appropriate for data structures that may contain large numbers of items. It is generally slower than a traditional HashMap, since lookups require a binary search and adds and removes require inserting and deleting entries in the array. For containers holding up to hundreds of items, the performance difference is not significant, less than 50%.
To help with performance, the container includes an optimization when removing keys: instead of compacting its array immediately, it leaves the removed entry marked as deleted. The entry can then be re-used for the same key, or compacted later in a single garbage collection step of all removed entries. This garbage collection will need to be performed at any time the array needs to be grown or the the map size or entry values are retrieved.
Public Constructors | |||||||||||
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Creates a new LongSparseArray containing no mappings.
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Creates a new LongSparseArray containing no mappings that will not
require any additional memory allocation to store the specified
number of mappings.
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Public Methods | |||||||||||
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Puts a key/value pair into the array, optimizing for the case where
the key is greater than all existing keys in the array.
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Removes all key-value mappings from this LongSparseArray.
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Creates and returns a copy of this
Object . | |||||||||||
Removes the mapping from the specified key, if there was any.
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Gets the Object mapped from the specified key, or the specified Object
if no such mapping has been made.
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Gets the Object mapped from the specified key, or
null
if no such mapping has been made. | |||||||||||
Returns the index for which
keyAt(int) would return the
specified key, or a negative number if the specified
key is not mapped. | |||||||||||
Returns an index for which
valueAt(int) would return the
specified key, or a negative number if no keys map to the
specified value. | |||||||||||
Given an index in the range
0...size()-1 , returns
the key from the index th key-value mapping that this
LongSparseArray stores. | |||||||||||
Adds a mapping from the specified key to the specified value,
replacing the previous mapping from the specified key if there
was one.
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Alias for
delete(long) . | |||||||||||
Removes the mapping at the specified index.
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Given an index in the range
0...size()-1 , sets a new
value for the index th key-value mapping that this
LongSparseArray stores. | |||||||||||
Returns the number of key-value mappings that this LongSparseArray
currently stores.
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Returns a string containing a concise, human-readable description of this
object.
This implementation composes a string by iterating over its mappings. | |||||||||||
Given an index in the range
0...size()-1 , returns
the value from the index th key-value mapping that this
LongSparseArray stores. |
[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
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Creates a new LongSparseArray containing no mappings.
Creates a new LongSparseArray containing no mappings that will not require any additional memory allocation to store the specified number of mappings. If you supply an initial capacity of 0, the sparse array will be initialized with a light-weight representation not requiring any additional array allocations.
Puts a key/value pair into the array, optimizing for the case where the key is greater than all existing keys in the array.
Removes all key-value mappings from this LongSparseArray.
Creates and returns a copy of this Object
. The default
implementation returns a so-called "shallow" copy: It creates a new
instance of the same class and then copies the field values (including
object references) from this instance to the new instance. A "deep" copy,
in contrast, would also recursively clone nested objects. A subclass that
needs to implement this kind of cloning should call super.clone()
to create the new instance and then create deep copies of the nested,
mutable objects.
Removes the mapping from the specified key, if there was any.
Gets the Object mapped from the specified key, or the specified Object if no such mapping has been made.
Gets the Object mapped from the specified key, or null
if no such mapping has been made.
Returns the index for which keyAt(int)
would return the
specified key, or a negative number if the specified
key is not mapped.
Returns an index for which valueAt(int)
would return the
specified key, or a negative number if no keys map to the
specified value.
Beware that this is a linear search, unlike lookups by key,
and that multiple keys can map to the same value and this will
find only one of them.
Given an index in the range 0...size()-1
, returns
the key from the index
th key-value mapping that this
LongSparseArray stores.
Adds a mapping from the specified key to the specified value, replacing the previous mapping from the specified key if there was one.
Removes the mapping at the specified index.
Given an index in the range 0...size()-1
, sets a new
value for the index
th key-value mapping that this
LongSparseArray stores.
Returns the number of key-value mappings that this LongSparseArray currently stores.
Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression:
getClass().getName() + '@' + Integer.toHexString(hashCode())
See Writing a useful
toString
method
if you intend implementing your own toString
method.
This implementation composes a string by iterating over its mappings. If this map contains itself as a value, the string "(this Map)" will appear in its place.
Given an index in the range 0...size()-1
, returns
the value from the index
th key-value mapping that this
LongSparseArray stores.