net.pwall.util

Class MiniMap<K,V>

java.lang.Object

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

Type Parameters:

K - the key type

V - the value type

All Implemented Interfaces:

Map<K,V>

Direct Known Subclasses:

MiniMap0, MiniMap1, MiniMap2, MiniMap3

public abstract class MiniMap<K,V>
extends Object
implements Map<K,V>

An implementation of Map to provide a simple and fast lookup mechanism for small numbers of keys.

Author:

Peter Wall

Nested Class Summary

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

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
MiniMap()

Method Summary

Modifier and Type	Method and Description
void	clear() Modifying operation - not allowed.
static <KK,VV> ImmutableMapEntry<KK,VV>	entry(KK key, VV value) Create an ImmutableMapEntry.
boolean	equals(Object other) Compares the specified object with this map for equality.
int	hashCode() Returns the hash code value for this map.
static <KK,VV> Map<KK,VV>	map(KK key, VV value) Create a MiniMap to map a single key to a nominated value.
static <KK,VV> Map<KK,VV>	map(KK key0, VV value0, KK key1, VV value1) Create a MiniMap to map two keys to two nominated values.
static <KK,VV> Map<KK,VV>	map(KK key0, VV value0, KK key1, VV value1, KK key2, VV value2) Create a MiniMap to map three keys to three nominated values.
static <KK,VV> Map<KK,VV>	of() Create an empty MiniMap.
static <KK,VV> Map<KK,VV>	of(Map.Entry<KK,VV>... entries) Create a MiniMap with a variable number of Map.Entrys.
static <KK,VV> Map<KK,VV>	of(Map.Entry<KK,VV> entry) Create a MiniMap with a single Map.Entry.
static <KK,VV> Map<KK,VV>	of(Map.Entry<KK,VV> entry0, Map.Entry<KK,VV> entry1) Create a MiniMap with two Map.Entrys.
static <KK,VV> Map<KK,VV>	of(Map.Entry<KK,VV> entry0, Map.Entry<KK,VV> entry1, Map.Entry<KK,VV> entry2) Create a MiniMap with three Map.Entrys.
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.
protected String	stringOf(Object obj) Return a string representation of the supplied key or value, guarding against possible recursion.
String	toString() Returns a string representation of this map.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, containsKey, containsValue, entrySet, forEach, get, getOrDefault, isEmpty, keySet, merge, putIfAbsent, remove, replace, replace, replaceAll, size, values

Constructor Detail

MiniMap

public MiniMap()

Method Detail

clear

public void clear()

Modifying operation - not allowed.

Specified by:

clear in interface Map<K,V>

Throws:

UnsupportedOperationException - (in all cases)

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)

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 collection

stringOf

protected String stringOf(Object obj)

Return a string representation of the supplied key or value, guarding against possible recursion.

Parameters:

obj - the object

Returns:

the string representation

entry

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

Create an ImmutableMapEntry.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

key - the key

value - the value

Returns:

the new ImmutableMapEntry

map

public static <KK,VV> Map<KK,VV> map(KK key,
                                     VV value)

Create a MiniMap to map a single key to a nominated value.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

key - the key

value - the value

Returns:

the new MiniMap

map

public static <KK,VV> Map<KK,VV> map(KK key0,
                                     VV value0,
                                     KK key1,
                                     VV value1)

Create a MiniMap to map two keys to two nominated values.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

key0 - the first key

value0 - the first value

key1 - the second key

value1 - the second value

Returns:

the new MiniMap

map

public static <KK,VV> Map<KK,VV> map(KK key0,
                                     VV value0,
                                     KK key1,
                                     VV value1,
                                     KK key2,
                                     VV value2)

Create a MiniMap to map three keys to three nominated values.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

key0 - the first key

value0 - the first value

key1 - the second key

value1 - the second value

key2 - the third key

value2 - the third value

Returns:

the new MiniMap

of

public static <KK,VV> Map<KK,VV> of()

Create an empty MiniMap.

Type Parameters:

KK - the key type

VV - the value type

Returns:

the new MiniMap

of

public static <KK,VV> Map<KK,VV> of(Map.Entry<KK,VV> entry)

Create a MiniMap with a single Map.Entry.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

entry - the entry

Returns:

the new MiniMap

of

public static <KK,VV> Map<KK,VV> of(Map.Entry<KK,VV> entry0,
                                    Map.Entry<KK,VV> entry1)

Create a MiniMap with two Map.Entrys.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

entry0 - the first entry

entry1 - the second entry

Returns:

the new MiniMap

of

public static <KK,VV> Map<KK,VV> of(Map.Entry<KK,VV> entry0,
                                    Map.Entry<KK,VV> entry1,
                                    Map.Entry<KK,VV> entry2)

Create a MiniMap with three Map.Entrys.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

entry0 - the first entry

entry1 - the second entry

entry2 - the third entry

Returns:

the new MiniMap

of

@SafeVarargs
public static <KK,VV> Map<KK,VV> of(Map.Entry<KK,VV>... entries)

Create a MiniMap with a variable number of Map.Entrys.

Type Parameters:

KK - the key type

VV - the value type

Parameters:

entries - the first entries

Returns:

the new MiniMap