net.pwall.util

Class ImmutableMap<K,V>

java.lang.Object

net.pwall.util.ImmutableBase<ImmutableMapEntry<K,V>>

net.pwall.util.ImmutableMap<K,V>

Type Parameters:

K - the key type

V - the value type

All Implemented Interfaces:

Map<K,V>

public class ImmutableMap<K,V>
extends ImmutableBase<ImmutableMapEntry<K,V>>
implements Map<K,V>

Immutable implementation of Map.

Author:

Peter Wall

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ImmutableMap.KeyIterator<K,V> Implementation of Iterator to iterate over the contents of a ImmutableMap.KeySet.
static class	ImmutableMap.KeySet<K,V> Implementation of the Set interface to provide a view of the keys in the ImmutableMap.
static class	ImmutableMap.ValueCollection<K,V> Implementation of the Collection interface to provide a view of the values in the ImmutableMap.
static class	ImmutableMap.ValueIterator<K,V> Implementation of Iterator to iterate over the contents of a ImmutableMap.ValueCollection.

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Field Summary

Fields

Modifier and Type	Field and Description
static ImmutableMapEntry<?,?>[]	emptyEntryArray

Constructor Summary

Constructors

Constructor and Description
ImmutableMap(ImmutableMapEntry<K,V>[] array) Construct an ImmutableList with the given array (using the entire array).
ImmutableMap(ImmutableMapEntry<K,V>[] array, int length) Construct an ImmutableMap with the given array (of ImmutableMapEntry) and length.
ImmutableMap(Map<K,V> map) Construct an ImmutableMap from another Map (helps with deserializing).

Method Summary

Modifier and Type	Method and Description
static <KK,VV> boolean	containsKey(ImmutableMapEntry<KK,VV>[] array, int length, KK key) Test whether an array of ImmutableMapEntry contains the specified key.
static <KK,VV> boolean	containsKey(List<ImmutableMapEntry<KK,VV>> list, KK key) Test whether a List of ImmutableMapEntry contains the specified key.
boolean	containsKey(Object key) Test whether the map contains a key equal to the specified key (which may be null).
boolean	containsValue(Object value) Test whether the map contains a value equal to the specified value (which may be null).
static <KK,VV> ImmutableMapEntry<KK,VV>[]	createArray(int length) Create an array of ImmutableMapEntry, of the specified length.
static <KK,VV> ImmutableMap<KK,VV>	emptyMap() Get an empty ImmutableMap.
static <KK,VV> ImmutableMapEntry<KK,VV>	entry(KK key, VV value) Create a ImmutableMapEntry.
ImmutableSet<Map.Entry<K,V>>	entrySet() Get a Set of the entries in this map.
boolean	equals(Object other) Compares the specified object with this map for equality.
static <KK,VV> int	findKey(ImmutableMapEntry<KK,VV>[] array, int length, Object key) Locate a key in an array of ImmutableMapEntry.
static <KK,VV> ImmutableMap<KK,VV>	from(List<ImmutableMapEntry<KK,VV>> list) Create an ImmutableMap from the supplied List of ImmutableMapEntry.
V	get(Object key) Get the value corresponding to the supplied key.
ImmutableMapEntry<K,V>	getEntry(int index) Get a map entry by index.
K	getKey(int index) Get a key by index.
V	getValue(int index) Get a value by index.
int	hashCode() Returns the hash code value for this map.
ImmutableMap.KeySet<K,V>	keySet() Get a Set of the keys in use in this map.
static <KK,VV> ImmutableMap<KK,VV>	mapOf(ImmutableMapEntry<KK,VV>[] array) Create an ImmutableMap from the supplied array of ImmutableMapEntry.
static <KK,VV> ImmutableMap<KK,VV>	mapOf(ImmutableMapEntry<KK,VV>[] array, int length) Create an ImmutableMap from the supplied array of ImmutableMapEntry with the specified length.
V	put(K key, V value) Modifying operation - not allowed.
void	putAll(Map<? extends K,? extends V> m) Modifying operation - not allowed.
V	remove(Object key) Modifying operation - not allowed.
String	toString() Returns a string representation of this map.
ImmutableMap.ValueCollection<K,V>	values() Get a Collection of the values in this map.

Methods inherited from class net.pwall.util.ImmutableBase

clear, isEmpty, size

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

clear, compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, isEmpty, merge, putIfAbsent, remove, replace, replace, replaceAll, size

Field Detail

emptyEntryArray

public static ImmutableMapEntry<?,?>[] emptyEntryArray

Constructor Detail

ImmutableMap

public ImmutableMap(ImmutableMapEntry<K,V>[] array,
                    int length)

Construct an ImmutableMap with the given array (of ImmutableMapEntry) and length.
**IMPORTANT – the map is immutable only if the array is not subsequently modified.**

Parameters:

array - the array of ImmutableMapEntry

length - the length (the number of array items to be considered part of the map)

Throws:

IndexOutOfBoundsException - if the length is less than 0 or greater than the array length

ImmutableMap

public ImmutableMap(ImmutableMapEntry<K,V>[] array)

Construct an ImmutableList with the given array (using the entire array).
**IMPORTANT – the map is immutable only if the array is not subsequently modified.**

Parameters:

array - the array of ImmutableMapEntry

ImmutableMap

public ImmutableMap(Map<K,V> map)

Construct an ImmutableMap from another Map (helps with deserializing).

Parameters:

map - the other Map

Method Detail

containsKey

public boolean containsKey(Object key)

Test whether the map contains a key equal to the specified key (which may be null).

Specified by:

containsKey in interface Map<K,V>

Parameters:

key - the key

Returns:

true if the map contains the key

containsValue

public boolean containsValue(Object value)

Test whether the map contains a value equal to the specified value (which may be null).

Specified by:

containsValue in interface Map<K,V>

Parameters:

value - the value

Returns:

true if the map contains the value

get

public V get(Object key)

Get the value corresponding to the supplied key. If the key is not found, null is returned.

Specified by:

get in interface Map<K,V>

Parameters:

key - the key

Returns:

the value

keySet

public ImmutableMap.KeySet<K,V> keySet()

Get a Set of the keys in use in this map. The set is backed by the original array, and retains the original order.

Specified by:

keySet in interface Map<K,V>

Returns:

the Set

values

public ImmutableMap.ValueCollection<K,V> values()

Get a Collection of the values in this map. The collection is backed by the original array, and retains the original order.

Specified by:

values in interface Map<K,V>

Returns:

the Collection

entrySet

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

Get a Set of the entries in this map. The set is backed by the original array, and retains the original order.

Specified by:

entrySet in interface Map<K,V>

Returns:

the Set

equals

public boolean equals(Object other)

Compares the specified object with this map for equality. Returns true if the given object is also a map, the maps contains the same number of entries and for each key in one map, the values returned by both maps are equal (either both are null, or they compare as equal using Object.equals(java.lang.Object)). This ensures that the equals method works properly across different implementations of the Map interface.

Specified by:

equals in interface Map<K,V>

Overrides:

equals in class Object

Parameters:

other - object to be compared for equality with this map

Returns:

true if the specified object is equal to this map

hashCode

public int hashCode()

Returns the hash code value for this map. The hash code of a map is defined to be the sum of the hash codes of each entry in the map's entrySet() view. This ensures that m1.equals(m2) implies that m1.hashCode() == m2.hashCode() for any two maps m1 and m2, as required by the general contract of Object.hashCode().

Specified by:

hashCode in interface Map<K,V>

Overrides:

hashCode in class Object

Returns:

the hash code value for this map

toString

public String toString()

Returns a string representation of this map. The string representation consists of the string representations of each of the entries (as key=value), enclosed in braces and separated by a comma and a space. Keys and values are converted to strings by String.valueOf(Object).

Overrides:

toString in class Object

Returns:

a string representation of this map

put

public V put(K key,
             V value)

Modifying operation - not allowed.

Specified by:

put in interface Map<K,V>

Throws:

UnsupportedOperationException - (in all cases)

remove

public V remove(Object key)

Modifying operation - not allowed.

Specified by:

remove in interface Map<K,V>

Throws:

UnsupportedOperationException - (in all cases)

putAll

public void putAll(Map<? extends K,? extends V> m)

Modifying operation - not allowed.

Specified by:

putAll in interface Map<K,V>

Throws:

UnsupportedOperationException - (in all cases)

getEntry

public final ImmutableMapEntry<K,V> getEntry(int index)

Get a map entry by index. This allows for very fast iteration over the entries of an ImmutableMap.
The function does not check the index because the indexing operation on the array will do that anyway.

Parameters:

index - the index

Returns:

the entry at that index

Throws:

IndexOutOfBoundsException - if the index is less than 0 or greater than the size of the map

getKey

public final K getKey(int index)

Get a key by index. This allows for very fast iteration over the keys of an ImmutableMap.
The function does not check the index because the indexing operation on the array will do that anyway.

Parameters:

index - the index

Returns:

the key at that index

Throws:

IndexOutOfBoundsException - if the index is less than 0 or greater than the size of the map

getValue

public final V getValue(int index)

Get a value by index. This allows for very fast iteration over the values of an ImmutableMap.
The function does not check the index because the indexing operation on the array will do that anyway.

Parameters:

index - the index

Returns:

the value at that index

Throws:

IndexOutOfBoundsException - if the index is less than 0 or greater than the size of the map

from

public static <KK,VV> ImmutableMap<KK,VV> from(List<ImmutableMapEntry<KK,VV>> list)

Create an ImmutableMap from the supplied List of ImmutableMapEntry.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

list - the List of ImmutableMapEntry

Returns:

the new ImmutableMap

emptyMap

public static <KK,VV> ImmutableMap<KK,VV> emptyMap()

Get an empty ImmutableMap. This avoids a memory allocation if the list is empty.

Type Parameters:

KK - the key type

VV - the value type

Returns:

an empty map

mapOf

public static <KK,VV> ImmutableMap<KK,VV> mapOf(ImmutableMapEntry<KK,VV>[] array)

Create an ImmutableMap from the supplied array of ImmutableMapEntry.
**IMPORTANT – the map is immutable only if the array is not subsequently modified.**

Type Parameters:

KK - the key type

VV - the value type

Parameters:

array - the array of ImmutableMapEntry

Returns:

the new ImmutableMap

mapOf

public static <KK,VV> ImmutableMap<KK,VV> mapOf(ImmutableMapEntry<KK,VV>[] array,
                                                int length)

Create an ImmutableMap from the supplied array of ImmutableMapEntry with the specified length.
**IMPORTANT – the map is immutable only if the array is not subsequently modified.**

Type Parameters:

KK - the key type

VV - the value type

Parameters:

array - the array of ImmutableMapEntry

length - the length (the number of array items to be considered part of the map)

Returns:

the new ImmutableMap

entry

public static <KK,VV> ImmutableMapEntry<KK,VV> entry(KK key,
                                                     VV value)

Create a ImmutableMapEntry.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

key - the key

value - the value

Returns:

the new ImmutableMapEntry

createArray

public static <KK,VV> ImmutableMapEntry<KK,VV>[] createArray(int length)

Create an array of ImmutableMapEntry, of the specified length.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

length - the length

Returns:

the new array

containsKey

public static <KK,VV> boolean containsKey(ImmutableMapEntry<KK,VV>[] array,
                                          int length,
                                          KK key)

Test whether an array of ImmutableMapEntry contains the specified key. The ImmutableMap constructor does not check for duplicate keys, so this function provides a means of checking prior to construction.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

array - the array

length - the length so far (the number of elements to be checked against)

key - the new key

Returns:

true if the key exists in the array

containsKey

public static <KK,VV> boolean containsKey(List<ImmutableMapEntry<KK,VV>> list,
                                          KK key)

Test whether a List of ImmutableMapEntry contains the specified key. The ImmutableMap constructor does not check for duplicate keys, so this function provides a means of checking prior to construction.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

list - the List

key - the new key

Returns:

true if the key exists in the List

findKey

public static <KK,VV> int findKey(ImmutableMapEntry<KK,VV>[] array,
                                  int length,
                                  Object key)

Locate a key in an array of ImmutableMapEntry. This is used both to check for duplicates prior to construction, and to find a value corresponding to a key in a map.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

array - the array

length - the length so far (the number of elements to be checked against)

key - the new key

Returns:

the index of the key in the array, or -1 if it is not found