Class ArrayMap<K,V> (1.42.2)

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.

Inheritance

Object > AbstractMap > ArrayMap<K,V>

Implements

Cloneable

Type Parameters

NameDescription
K
V

Static Methods

<K,V>create()

public static ArrayMap<K,V> <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();.

Returns
TypeDescription
ArrayMap<K,V>

<K,V>create(int initialCapacity)

public static ArrayMap<K,V> <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);.

Parameter
NameDescription
initialCapacityint
Returns
TypeDescription
ArrayMap<K,V>

<K,V>of(Object[] keyValuePairs)

public static ArrayMap<K,V> <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.

Parameter
NameDescription
keyValuePairsObject[]
Returns
TypeDescription
ArrayMap<K,V>

Constructors

ArrayMap()

public ArrayMap()

Methods

add(K key, V value)

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).

Parameters
NameDescription
keyK
valueV

clear()

public void clear()
Overrides

clone()

public ArrayMap<K,V> clone()
Returns
TypeDescription
ArrayMap<K,V>
Overrides

containsKey(Object key)

public final boolean containsKey(Object key)

Returns whether there is a mapping for the given key.

Parameter
NameDescription
keyObject
Returns
TypeDescription
boolean
Overrides

containsValue(Object value)

public final boolean containsValue(Object value)
Parameter
NameDescription
valueObject
Returns
TypeDescription
boolean
Overrides

ensureCapacity(int minCapacity)

public final void ensureCapacity(int minCapacity)

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

Parameter
NameDescription
minCapacityint

entrySet()

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

get(Object key)

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.

Parameter
NameDescription
keyObject
Returns
TypeDescription
V
Overrides

getIndexOfKey(K key)

public final int getIndexOfKey(K key)

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

Parameter
NameDescription
keyK
Returns
TypeDescription
int

getKey(int index)

public final K getKey(int index)

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

Parameter
NameDescription
indexint
Returns
TypeDescription
K

getValue(int index)

public final V getValue(int index)

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

Parameter
NameDescription
indexint
Returns
TypeDescription
V

put(K key, V value)

public final V put(K key, V value)

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

Parameters
NameDescription
keyK
valueV
Returns
TypeDescription
V

previous value or null for none

Overrides

remove(int index)

public final V remove(int index)

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

Parameter
NameDescription
indexint
Returns
TypeDescription
V

previous value or null for none

remove(Object key)

public final V remove(Object key)

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

Parameter
NameDescription
keyObject
Returns
TypeDescription
V

previous value or null for none

Overrides

set(int index, K key, V value)

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.

Parameters
NameDescription
indexint
keyK
valueV
Returns
TypeDescription
V

previous value or null for none

set(int index, V value)

public final V set(int index, V value)

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

Parameters
NameDescription
indexint
valueV
Returns
TypeDescription
V

previous value or null for none

size()

public final int size()

Returns the number of key-value pairs set.

Returns
TypeDescription
int
Overrides

trim()

public final void trim()

Trims the internal array storage to minimize memory usage.