com.google.api.client.util

Class ArrayMap<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

com.google.api.client.util.ArrayMap<K,V>

Type Parameters:

K - the type of keys maintained by this map

V - the type of mapped values

All Implemented Interfaces:

Cloneable, Map<K,V>

public class ArrayMap<K,V>
extends AbstractMap<K,V>
implements Cloneable

Memory-efficient map of keys to values with list-style random-access semantics.

Supports null keys and values. Conceptually, the keys and values are stored in a simpler array in order to minimize memory use and provide for fast access to a key/value at a certain index (for example getKey(int)). However, traditional mapping operations like get(Object) and put(Object, Object) are slower because they need to look up all key/value pairs in the worst case.

Implementation is not thread-safe. For a thread-safe choice instead use an implementation of ConcurrentMap.

Since:

1.0

Author:

Yaniv Inbar

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>

Constructor Summary

Constructors

Constructor and Description
ArrayMap()

Method Summary

Methods

Modifier and Type	Method and Description
void	add(K key, V value) Adds the key/value mapping at the end of the list.
void	clear()
ArrayMap<K,V>	clone()
boolean	containsKey(Object key) Returns whether there is a mapping for the given key.
boolean	containsValue(Object value)
static <K,V> ArrayMap<K,V>	create() Returns a new instance of an array map with initial capacity of zero.
static <K,V> ArrayMap<K,V>	create(int initialCapacity) Returns a new instance of an array map of the given initial capacity.
void	ensureCapacity(int minCapacity) Ensures that the capacity of the internal arrays is at least a given capacity.
Set<Map.Entry<K,V>>	entrySet()
V	get(Object key) Returns the value set for the given key or null if there is no such mapping or if the mapping value is null.
int	getIndexOfKey(K key) Returns the index of the given key or -1 if there is no such key.
K	getKey(int index) Returns the key at the given index or null if out of bounds.
V	getValue(int index) Returns the value at the given index or null if out of bounds.
static <K,V> ArrayMap<K,V>	of(Object... keyValuePairs) Returns a new instance of an array map of the given key value pairs in alternating order.
V	put(K key, V value) Sets the value for the given key, overriding any existing value.
V	remove(int index) Removes the key/value mapping at the given index, or ignored if the index is out of bounds.
V	remove(Object key) Removes the key-value pair of the given key, or ignore if the key cannot be found.
V	set(int index, K key, V value) Sets the key/value mapping at the given index, overriding any existing key/value mapping.
V	set(int index, V value) Sets the value at the given index, overriding any existing value mapping.
int	size() Returns the number of key-value pairs set.
void	trim() Trims the internal array storage to minimize memory usage.

Methods inherited from class java.util.AbstractMap

equals, hashCode, isEmpty, keySet, putAll, toString, values

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ArrayMap

public ArrayMap()

Method Detail

create

public static <K,V> ArrayMap<K,V> create()

Returns a new instance of an array map with initial capacity of zero. Equivalent to calling the default constructor, except without the need to specify the type parameters. For example: ArrayMap<String, String> map = ArrayMap.create();.

create

public static <K,V> ArrayMap<K,V> create(int initialCapacity)

Returns a new instance of an array map of the given initial capacity. For example: ArrayMap<String, String> map = ArrayMap.create(8);.

of

public static <K,V> ArrayMap<K,V> of(Object... keyValuePairs)

Returns a new instance of an array map of the given key value pairs in alternating order. For example: ArrayMap<String, String> map = ArrayMap.of("key1", "value1", "key2", "value2", ...);.

WARNING: there is no compile-time checking of the keyValuePairs parameter to ensure that the keys or values have the correct type, so if the wrong type is passed in, any problems will occur at runtime. Also, there is no checking that the keys are unique, which the caller must ensure is true.

size

public final int size()

Returns the number of key-value pairs set.

Specified by:

size in interface Map<K,V>

Overrides:

size in class AbstractMap<K,V>

getKey

public final K getKey(int index)

Returns the key at the given index or null if out of bounds.

getValue

public final V getValue(int index)

Returns the value at the given index or null if out of bounds.

set

public final V set(int index,
    K key,
    V value)

Sets the key/value mapping at the given index, overriding any existing key/value mapping.

There is no checking done to ensure that the key does not already exist. Therefore, this method is dangerous to call unless the caller can be certain the key does not already exist in the map.

Returns:

previous value or null for none

Throws:

IndexOutOfBoundsException - if index is negative

set

public final V set(int index,
    V value)

Sets the value at the given index, overriding any existing value mapping.

Returns:

previous value or null for none

Throws:

IndexOutOfBoundsException - if index is negative or >= size

add

public final void add(K key,
       V value)

Adds the key/value mapping at the end of the list. Behaves identically to set(size(), key, value).

Throws:

IndexOutOfBoundsException - if index is negative

remove

public final V remove(int index)

Removes the key/value mapping at the given index, or ignored if the index is out of bounds.

Returns:

previous value or null for none

containsKey

public final boolean containsKey(Object key)

Returns whether there is a mapping for the given key.

Specified by:

containsKey in interface Map<K,V>

Overrides:

containsKey in class AbstractMap<K,V>

getIndexOfKey

public final int getIndexOfKey(K key)

Returns the index of the given key or -1 if there is no such key.

get

public final V get(Object key)

Returns the value set for the given key or null if there is no such mapping or if the mapping value is null.

Specified by:

get in interface Map<K,V>

Overrides:

get in class AbstractMap<K,V>

put

public final V put(K key,
    V value)

Sets the value for the given key, overriding any existing value.

Specified by:

put in interface Map<K,V>

Overrides:

put in class AbstractMap<K,V>

Returns:

previous value or null for none

remove

public final V remove(Object key)

Removes the key-value pair of the given key, or ignore if the key cannot be found.

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class AbstractMap<K,V>

Returns:

previous value or null for none

trim

public final void trim()

Trims the internal array storage to minimize memory usage.

ensureCapacity

public final void ensureCapacity(int minCapacity)

Ensures that the capacity of the internal arrays is at least a given capacity.

clear

public void clear()

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class AbstractMap<K,V>

containsValue

public final boolean containsValue(Object value)

Specified by:

containsValue in interface Map<K,V>

Overrides:

containsValue in class AbstractMap<K,V>

entrySet

public final Set<Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface Map<K,V>

Specified by:

entrySet in class AbstractMap<K,V>

clone

public ArrayMap<K,V> clone()

Overrides:

clone in class AbstractMap<K,V>