java.lang.Object | |
↳ | android.util.SparseBooleanArray |
SparseBooleanArrays map integers to booleans. Unlike a normal array of booleans there can be gaps in the indices. It is intended to be more memory efficient than using a HashMap to map Integers to Booleans, both because it avoids auto-boxing keys and values 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%.
It is possible to iterate over the items in this container using
keyAt(int)
and valueAt(int)
. Iterating over the keys using
keyAt(int)
with ascending values of the index will return the
keys in ascending order, or the values corresponding to the keys in ascending
order in the case of valueAt(int)
.
Public Constructors | |||||||||||
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Creates a new SparseBooleanArray containing no mappings.
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Creates a new SparseBooleanArray 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 SparseBooleanArray.
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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 boolean mapped from the specified key, or
false
if no such mapping has been made. | |||||||||||
Gets the boolean mapped from the specified key, or the specified value
if no such mapping has been made.
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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
SparseBooleanArray 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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Returns the number of key-value mappings that this SparseBooleanArray
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
SparseBooleanArray stores. |
[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
|
Creates a new SparseBooleanArray containing no mappings.
Creates a new SparseBooleanArray 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 SparseBooleanArray.
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 boolean mapped from the specified key, or false
if no such mapping has been made.
Gets the boolean mapped from the specified key, or the specified value 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
SparseBooleanArray stores.
The keys corresponding to indices in ascending order are guaranteed to
be in ascending order, e.g., keyAt(0)
will return the
smallest key and keyAt(size()-1)
will return the largest
key.
Adds a mapping from the specified key to the specified value, replacing the previous mapping from the specified key if there was one.
Returns the number of key-value mappings that this SparseBooleanArray 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.
Given an index in the range 0...size()-1
, returns
the value from the index
th key-value mapping that this
SparseBooleanArray stores.
The values corresponding to indices in ascending order are guaranteed
to be associated with keys in ascending order, e.g.,
valueAt(0)
will return the value associated with the
smallest key and valueAt(size()-1)
will return the value
associated with the largest key.