squidpony.squidmath

Class UnorderedMap<K,V>

java.lang.Object

squidpony.squidmath.UnorderedMap<K,V>

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.util.Map<K,V>

public class UnorderedMap<K,V>
extends java.lang.Object
implements java.util.Map<K,V>, java.io.Serializable, java.lang.Cloneable

A generic unordered hash map; generally prefer HashMap unless you need array keys. Originally from fastutil as Object2ObjectOpenCustomHashMap but modified to support SquidLib's CrossHash.IHasher interface for custom hashing instead of fastutil's Strategy interface.
Instances of this class use a hash table to represent a map. The table is filled up to a specified load factor, and then doubled in size to accommodate new entries. If the table is emptied below one fourth of the load factor, it is halved in size. However, halving is not performed when deleting entries from an iterator, as it would interfere with the iteration process.
Note that clear() does not modify the hash table size. Rather, a family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.
You can pass a CrossHash.IHasher instance such as CrossHash.generalHasher as an extra parameter to most of this class' constructors, which allows the OrderedMap to use arrays (usually primitive arrays) as keys. If you expect only one type of array, you can use an instance like CrossHash.intHasher to hash int arrays, or the aforementioned generalHasher to hash most kinds of arrays (it can't handle most multi-dimensional arrays well). If you aren't using arrays as keys, you don't need to give an IHasher to the constructor and can ignore this feature most of the time. However, the default IHasher this uses if none is specified performs a small but significant "mixing" step to make the default generated hashCode() implementation many classes use into a higher-quality random-like value. This isn't always optimal; if you plan to insert 1000 sequential Integer keys with some small amount of random Integers after them, then the mixing actually increases the likelihood of a collision and takes time to calculate. You could use a very simple IHasher in that case, relying on the fact that only Integers will be added:

 new CrossHash.IHasher() {
     public int hash(Object data) { return (int)data; }
     public boolean areEqual(Object left, Object right) { return Objects.equals(left, right); }
 };
 

This is just one example of a case where a custom IHasher can be useful for performance reasons; there are also cases where an IHasher is needed to enforce hashing by identity or by value, which affect program logic. Note that the given IHasher is likely to be sub-optimal for many situations with Integer keys, and you may want to try a few different approaches if you know OrderedMap is a bottleneck in your application. If the IHasher is a performance problem, it will be at its worst if the OrderedMap needs to resize, and thus rehash, many times; this won't happen if the capacity is set correctly when the OrderedMap is created (with the capacity equal to or greater than the maximum number of entries that will be added).
Thank you, Sebastiano Vigna, for making FastUtil available to the public with such high quality.
See https://github.com/vigna/fastutil for the original library.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	UnorderedMap.ValueCollection

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

java.util.Map.Entry<K,V>

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	containsNullKey Whether this set contains the key zero.
static int	DEFAULT_INITIAL_SIZE The initial default size of a hash table.
static float	DEFAULT_LOAD_FACTOR The default load factor of a hash table.
protected V	defRetValue Default return value.
protected squidpony.squidmath.UnorderedMap.MapEntrySet	entries Cached set of entries.
float	f The acceptable load factor.
static float	FAST_LOAD_FACTOR The load factor for a (usually small) table that is meant to be particularly fast.
protected CrossHash.IHasher	hasher
protected K[]	key The array of keys.
protected squidpony.squidmath.UnorderedMap.KeySet	keys Cached set of keys.
protected int	mask The mask for wrapping a position counter.
protected int	maxFill Threshold after which we rehash.
protected int	n The current table size.
protected int	size Number of entries in the set (including the key zero, if present).
protected V[]	value The array of values.
protected java.util.Collection<V>	values Cached collection of values.
static float	VERY_FAST_LOAD_FACTOR The load factor for a (usually very small) table that is meant to be extremely fast.

Constructor Summary

Constructors

Constructor and Description
UnorderedMap() Creates a new OrderedMap with initial expected 16 entries and 0.75f as load factor.
UnorderedMap(java.util.Collection<K> keyColl, java.util.Collection<V> valueColl) Creates a new OrderedMap using the elements of two parallel arrays.
UnorderedMap(java.util.Collection<K> keyColl, java.util.Collection<V> valueColl, float f) Creates a new OrderedMap using the elements of two parallel arrays.
UnorderedMap(CrossHash.IHasher hasher) Creates a new OrderedMap with initial expected 16 entries and 0.75f as load factor.
UnorderedMap(int expected) Creates a new OrderedMap with 0.75f as load factor.
UnorderedMap(int expected, CrossHash.IHasher hasher) Creates a new OrderedMap with 0.75f as load factor.
UnorderedMap(int expected, float f) Creates a new OrderedMap.
UnorderedMap(int expected, float f, CrossHash.IHasher hasher) Creates a new OrderedMap.
UnorderedMap(K[] keyArray, V[] valueArray) Creates a new OrderedMap with 0.75f as load factor using the elements of two parallel arrays.
UnorderedMap(K[] keyArray, V[] valueArray, CrossHash.IHasher hasher) Creates a new OrderedMap with 0.75f as load factor using the elements of two parallel arrays.
UnorderedMap(K[] keyArray, V[] valueArray, float f) Creates a new OrderedMap using the elements of two parallel arrays.
UnorderedMap(K[] keyArray, V[] valueArray, float f, CrossHash.IHasher hasher) Creates a new OrderedMap using the elements of two parallel arrays.
UnorderedMap(java.util.Map<? extends K,? extends V> m) Creates a new OrderedMap with 0.75f as load factor copying a given one.
UnorderedMap(java.util.Map<? extends K,? extends V> m, CrossHash.IHasher hasher) Creates a new OrderedMap with 0.75f as load factor copying a given one.
UnorderedMap(java.util.Map<? extends K,? extends V> m, float f) Creates a new OrderedMap copying a given one.
UnorderedMap(java.util.Map<? extends K,? extends V> m, float f, CrossHash.IHasher hasher) Creates a new OrderedMap copying a given one.

Method Summary

Modifier and Type	Method and Description
static int	arraySize(int expected, float f) Returns the least power of two smaller than or equal to 230 and larger than or equal to Math.ceil( expected / f ).
void	clear()
UnorderedMap<K,V>	clone() Returns a deep copy of this map.
boolean	containsKey(java.lang.Object k)
boolean	containsValue(java.lang.Object v)
V	defaultReturnValue()
void	defaultReturnValue(V rv)
java.util.Set<java.util.Map.Entry<K,V>>	entrySet()
boolean	equals(java.lang.Object o)
V	get(java.lang.Object k)
java.util.List<V>	getMany(java.util.Collection<K> keys)
V	getOrDefault(java.lang.Object k, V defaultValue)
long	hash64()
int	hashCode() Returns a hash code for this map.
boolean	isEmpty()
java.util.Set<K>	keySet()
static <K,V> UnorderedMap<K,V>	makeMap() Makes an empty OrderedMap (OM); needs key and value types to be specified in order to work.
static <K,V> UnorderedMap<K,V>	makeMap(K k0, V v0, java.lang.Object... rest) Makes an OrderedMap (OM) with the given load factor (which should be between 0.1 and 0.9), key and value types inferred from the types of k0 and v0, and considers all remaining parameters key-value pairs, casting the Objects at positions 0, 2, 4...
static int	maxFill(int n, float f) Returns the maximum number of entries that can be filled before rehashing.
protected int	positionOf(java.lang.Object k)
V	put(K k, V v)
void	putAll(K[] keyArray, V[] valueArray) Puts the first key in keyArray with the first value in valueArray, then the second in each and so on.
void	putAll(java.util.Map<? extends K,? extends V> m) Puts all key-value pairs in the Map m into this OrderedMap.
V	putIfAbsent(K key, V value) If the specified key is not already associated with a value (or is mapped to null) associates it with the given value and returns null, else returns the current value.
UnorderedMap<K,V>	putPairs(K k0, V v0, java.lang.Object... rest) Given alternating key and value arguments in pairs, puts each key-value pair into this OrderedMap as if by calling put(Object, Object) repeatedly for each pair.
protected void	rehash(int newN) Rehashes the map.
V	remove(java.lang.Object k)
boolean	remove(java.lang.Object key, java.lang.Object value) Removes the entry for the specified key only if it is currently mapped to the specified value.
V	replace(K key, V value) Replaces the entry for the specified key only if it is currently mapped to some value.
boolean	replace(K key, V oldValue, V newValue) Replaces the entry for the specified key only if currently mapped to the specified value.
protected void	shiftKeys(int pos) Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.
int	size()
java.lang.String	toString()
boolean	trim() Rehashes the map, making the table as small as possible.
boolean	trim(int n) Rehashes this map if the table is too large.
java.util.Collection<V>	values()
java.util.ArrayList<V>	valuesAsList()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, forEach, merge, replaceAll

Field Detail

key

protected K[] key

The array of keys.

value

protected V[] value

The array of values.

mask

protected int mask

The mask for wrapping a position counter.

containsNullKey

protected boolean containsNullKey

Whether this set contains the key zero.

n

protected int n

The current table size.

maxFill

protected int maxFill

Threshold after which we rehash. It must be the table size times f.

size

protected int size

Number of entries in the set (including the key zero, if present).

f

public final float f

The acceptable load factor.

entries

protected volatile squidpony.squidmath.UnorderedMap.MapEntrySet entries

Cached set of entries.

keys

protected volatile squidpony.squidmath.UnorderedMap.KeySet keys

Cached set of keys.

values

protected volatile java.util.Collection<V> values

Cached collection of values.

defRetValue

protected V defRetValue

Default return value.

DEFAULT_INITIAL_SIZE

public static final int DEFAULT_INITIAL_SIZE

The initial default size of a hash table.

See Also:

Constant Field Values

DEFAULT_LOAD_FACTOR

public static final float DEFAULT_LOAD_FACTOR

The default load factor of a hash table.

See Also:

Constant Field Values

FAST_LOAD_FACTOR

public static final float FAST_LOAD_FACTOR

The load factor for a (usually small) table that is meant to be particularly fast.

See Also:

Constant Field Values

VERY_FAST_LOAD_FACTOR

public static final float VERY_FAST_LOAD_FACTOR

The load factor for a (usually very small) table that is meant to be extremely fast.

See Also:

Constant Field Values

hasher

protected final CrossHash.IHasher hasher

Constructor Detail

UnorderedMap

public UnorderedMap(int expected,
                    float f)

Creates a new OrderedMap.

The actual table size will be the least power of two greater than expected/f.

Parameters:

expected - the expected number of elements in the hash set.

f - the load factor.

UnorderedMap

public UnorderedMap(int expected)

Creates a new OrderedMap with 0.75f as load factor.

Parameters:

expected - the expected number of elements in the OrderedMap.

UnorderedMap

public UnorderedMap()

Creates a new OrderedMap with initial expected 16 entries and 0.75f as load factor.

UnorderedMap

public UnorderedMap(java.util.Map<? extends K,? extends V> m,
                    float f)

Creates a new OrderedMap copying a given one.

Parameters:

m - a Map to be copied into the new OrderedMap.

f - the load factor.

UnorderedMap

public UnorderedMap(java.util.Map<? extends K,? extends V> m)

Creates a new OrderedMap with 0.75f as load factor copying a given one.

Parameters:

m - a Map to be copied into the new OrderedMap.

UnorderedMap

public UnorderedMap(K[] keyArray,
                    V[] valueArray,
                    float f)

Creates a new OrderedMap using the elements of two parallel arrays.

Parameters:

keyArray - the array of keys of the new OrderedMap.

valueArray - the array of corresponding values in the new OrderedMap.

f - the load factor.

Throws:

java.lang.IllegalArgumentException - if k and v have different lengths.

UnorderedMap

public UnorderedMap(java.util.Collection<K> keyColl,
                    java.util.Collection<V> valueColl)

Creates a new OrderedMap using the elements of two parallel arrays.

Parameters:

keyColl - the collection of keys of the new OrderedMap.

valueColl - the collection of corresponding values in the new OrderedMap.

Throws:

java.lang.IllegalArgumentException - if k and v have different lengths.

UnorderedMap

public UnorderedMap(java.util.Collection<K> keyColl,
                    java.util.Collection<V> valueColl,
                    float f)

Creates a new OrderedMap using the elements of two parallel arrays.

Parameters:

keyColl - the collection of keys of the new OrderedMap.

valueColl - the collection of corresponding values in the new OrderedMap.

f - the load factor.

Throws:

java.lang.IllegalArgumentException - if k and v have different lengths.

UnorderedMap

public UnorderedMap(K[] keyArray,
                    V[] valueArray)

Creates a new OrderedMap with 0.75f as load factor using the elements of two parallel arrays.

Parameters:

keyArray - the array of keys of the new OrderedMap.

valueArray - the array of corresponding values in the new OrderedMap.

Throws:

java.lang.IllegalArgumentException - if k and v have different lengths.

UnorderedMap

public UnorderedMap(int expected,
                    float f,
                    CrossHash.IHasher hasher)

Creates a new OrderedMap.

The actual table size will be the least power of two greater than expected/f.

Parameters:

expected - the expected number of elements in the hash set.

f - the load factor.

hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations

UnorderedMap

public UnorderedMap(int expected,
                    CrossHash.IHasher hasher)

Creates a new OrderedMap with 0.75f as load factor.

Parameters:

expected - the expected number of elements in the OrderedMap.

hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations

UnorderedMap

public UnorderedMap(CrossHash.IHasher hasher)

Creates a new OrderedMap with initial expected 16 entries and 0.75f as load factor.

UnorderedMap

public UnorderedMap(java.util.Map<? extends K,? extends V> m,
                    float f,
                    CrossHash.IHasher hasher)

Creates a new OrderedMap copying a given one.

Parameters:

m - a Map to be copied into the new OrderedMap.

f - the load factor.

hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations

UnorderedMap

public UnorderedMap(java.util.Map<? extends K,? extends V> m,
                    CrossHash.IHasher hasher)

Creates a new OrderedMap with 0.75f as load factor copying a given one.

Parameters:

m - a Map to be copied into the new OrderedMap.

hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations

UnorderedMap

public UnorderedMap(K[] keyArray,
                    V[] valueArray,
                    float f,
                    CrossHash.IHasher hasher)

Creates a new OrderedMap using the elements of two parallel arrays.

Parameters:

keyArray - the array of keys of the new OrderedMap.

valueArray - the array of corresponding values in the new OrderedMap.

f - the load factor.

hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations

Throws:

java.lang.IllegalArgumentException - if k and v have different lengths.

UnorderedMap

public UnorderedMap(K[] keyArray,
                    V[] valueArray,
                    CrossHash.IHasher hasher)

Creates a new OrderedMap with 0.75f as load factor using the elements of two parallel arrays.

Parameters:

keyArray - the array of keys of the new OrderedMap.

valueArray - the array of corresponding values in the new OrderedMap.

hasher - used to hash items; typically only needed when K is an array, where CrossHash has implementations

Throws:

java.lang.IllegalArgumentException - if k and v have different lengths.

Method Detail

defaultReturnValue

public void defaultReturnValue(V rv)

defaultReturnValue

public V defaultReturnValue()

putAll

public void putAll(K[] keyArray,
                   V[] valueArray)

Puts the first key in keyArray with the first value in valueArray, then the second in each and so on. The entries are all appended to the end of the iteration order, unless a key was already present. Then, its value is changed at the existing position in the iteration order. If the lengths of the two arrays are not equal, this puts a number of entries equal to the lesser length. If either array is null, this returns without performing any changes.

Parameters:

keyArray - an array of K keys that should usually have the same length as valueArray

valueArray - an array of V values that should usually have the same length as keyArray

putAll

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

Puts all key-value pairs in the Map m into this OrderedMap. The entries are all appended to the end of the iteration order, unless a key was already present. Then, its value is changed at the existing position in the iteration order. This can take any kind of Map, including unordered HashMap objects; if the Map does not have stable ordering, the order in which entries will be appended is not stable either. For this reason, OrderedMap, LinkedHashMap, and TreeMap (or other SortedMap implementations) will work best when order matters.

Specified by:

putAll in interface java.util.Map<K,V>

Parameters:

m - a Map that should have the same or compatible K key and V value types; OrderedMap and TreeMap work best

put

public V put(K k,
             V v)

Specified by:

put in interface java.util.Map<K,V>

shiftKeys

protected final void shiftKeys(int pos)

Shifts left entries with the specified hash code, starting at the specified position, and empties the resulting free entry.

Parameters:

pos - a starting position.

remove

public V remove(java.lang.Object k)

Specified by:

remove in interface java.util.Map<K,V>

get

public V get(java.lang.Object k)

Specified by:

get in interface java.util.Map<K,V>

getOrDefault

public V getOrDefault(java.lang.Object k,
                      V defaultValue)

Specified by:

getOrDefault in interface java.util.Map<K,V>

positionOf

protected int positionOf(java.lang.Object k)

containsKey

public boolean containsKey(java.lang.Object k)

Specified by:

containsKey in interface java.util.Map<K,V>

containsValue

public boolean containsValue(java.lang.Object v)

Specified by:

containsValue in interface java.util.Map<K,V>

clear

public void clear()

Specified by:

clear in interface java.util.Map<K,V>

size

public int size()

Specified by:

size in interface java.util.Map<K,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Map<K,V>

entrySet

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

Specified by:

entrySet in interface java.util.Map<K,V>

keySet

public java.util.Set<K> keySet()

Specified by:

keySet in interface java.util.Map<K,V>

values

public java.util.Collection<V> values()

Specified by:

values in interface java.util.Map<K,V>

valuesAsList

public java.util.ArrayList<V> valuesAsList()

trim

public boolean trim()

Rehashes the map, making the table as small as possible.

This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.

If the table size is already the minimum possible, this method does nothing.

Returns:

true if there was enough memory to trim the map.

See Also:

trim(int)

trim

public boolean trim(int n)

Rehashes this map if the table is too large.

Let N be the smallest table size that can hold max(n,size()) entries, still satisfying the load factor. If the current table size is smaller than or equal to N, this method does nothing. Otherwise, it rehashes this map in a table of size N.

This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps.

Parameters:

n - the threshold for the trimming.

Returns:

true if there was enough memory to trim the map.

See Also:

trim()

rehash

protected void rehash(int newN)

Rehashes the map.

This method implements the basic rehashing strategy, and may be overriden by subclasses implementing different rehashing strategies (e.g., disk-based rehashing). However, you should not override this method unless you understand the internal workings of this class.

Parameters:

newN - the new size

clone

public UnorderedMap<K,V> clone()

Returns a deep copy of this map.

This method performs a deep copy of this OrderedMap; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.

Overrides:

clone in class java.lang.Object

Returns:

a deep copy of this map.

hashCode

public int hashCode()

Returns a hash code for this map. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.

Specified by:

hashCode in interface java.util.Map<K,V>

Overrides:

hashCode in class java.lang.Object

Returns:

a hash code for this map.

hash64

public long hash64()

maxFill

public static int maxFill(int n,
                          float f)

Returns the maximum number of entries that can be filled before rehashing.

Parameters:

n - the size of the backing array.

f - the load factor.

Returns:

the maximum number of entries before rehashing.

arraySize

public static int arraySize(int expected,
                            float f)

Returns the least power of two smaller than or equal to 2³⁰ and larger than or equal to Math.ceil( expected / f ). re

Parameters:

expected - the expected number of elements in a hash table.

f - the load factor.

Returns:

the minimum possible size for a backing array.

Throws:

java.lang.IllegalArgumentException - if the necessary size is larger than 2³⁰.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

equals

public boolean equals(java.lang.Object o)

Specified by:

equals in interface java.util.Map<K,V>

Overrides:

equals in class java.lang.Object

getMany

public java.util.List<V> getMany(java.util.Collection<K> keys)

putIfAbsent

public V putIfAbsent(K key,
                     V value)

If the specified key is not already associated with a value (or is mapped to null) associates it with the given value and returns null, else returns the current value.

Specified by:

putIfAbsent in interface java.util.Map<K,V>

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key.)

remove

public boolean remove(java.lang.Object key,
                      java.lang.Object value)

Removes the entry for the specified key only if it is currently mapped to the specified value.

Specified by:

remove in interface java.util.Map<K,V>

Parameters:

key - key with which the specified value is associated

value - value expected to be associated with the specified key

Returns:

true if the value was removed

replace

public boolean replace(K key,
                       V oldValue,
                       V newValue)

Replaces the entry for the specified key only if currently mapped to the specified value. The position in the iteration order is retained.

Specified by:

replace in interface java.util.Map<K,V>

Parameters:

key - key with which the specified value is associated

oldValue - value expected to be associated with the specified key

newValue - value to be associated with the specified key

Returns:

true if the value was replaced

replace

public V replace(K key,
                 V value)

Replaces the entry for the specified key only if it is currently mapped to some value. Preserves the existing key's position in the iteration order.

Specified by:

replace in interface java.util.Map<K,V>

Parameters:

key - key with which the specified value is associated

value - value to be associated with the specified key

Returns:

the previous value associated with the specified key, or null if there was no mapping for the key. (A null return can also indicate that the map previously associated null with the key.)

putPairs

public UnorderedMap<K,V> putPairs(K k0,
                                  V v0,
                                  java.lang.Object... rest)

Given alternating key and value arguments in pairs, puts each key-value pair into this OrderedMap as if by calling put(Object, Object) repeatedly for each pair. This mimics the parameter syntax used for makeMap(Object, Object, Object...), and can be used to retain that style of insertion after an OrderedMap has been instantiated.

Parameters:

k0 - the first key to add

v0 - the first value to add

rest - an array or vararg of keys and values in pairs; should contain alternating K, V, K, V... elements

Returns:

this, after adding all viable key-value pairs given

makeMap

public static <K,V> UnorderedMap<K,V> makeMap(K k0,
                                              V v0,
                                              java.lang.Object... rest)

Makes an OrderedMap (OM) with the given load factor (which should be between 0.1 and 0.9), key and value types inferred from the types of k0 and v0, and considers all remaining parameters key-value pairs, casting the Objects at positions 0, 2, 4... etc. to K and the objects at positions 1, 3, 5... etc. to V. If rest has an odd-number length, then it discards the last item. If any pair of items in rest cannot be cast to the correct type of K or V, then this inserts nothing for that pair. This is similar to the makeOM method in the Maker class, but does not allow setting the load factor (since that extra parameter can muddle how javac figures out which generic types the map should use), nor does it log debug information if a cast fails. The result should be the same otherwise.
This is named makeMap to indicate that it expects key and value parameters, unlike a Set or List. This convention may be extended to other data structures that also have static methods for instantiation.

Type Parameters:

K - the type of keys in the returned OrderedMap; if not specified, will be inferred from k0

V - the type of values in the returned OrderedMap; if not specified, will be inferred from v0

Parameters:

k0 - the first key; used to infer the types of other keys if generic parameters aren't specified.

v0 - the first value; used to infer the types of other values if generic parameters aren't specified.

rest - an array or vararg of keys and values in pairs; should contain alternating K, V, K, V... elements

Returns:

a freshly-made OrderedMap with K keys and V values, using k0, v0, and the contents of rest to fill it

makeMap

public static <K,V> UnorderedMap<K,V> makeMap()

Makes an empty OrderedMap (OM); needs key and value types to be specified in order to work. For an empty OrderedMap with String keys and Coord values, you could use Maker.<String, Coord>makeOM(). Using the new keyword is probably just as easy in this case; this method is provided for completeness relative to makeMap() with 2 or more parameters.

Type Parameters:

K - the type of keys in the returned OrderedMap; cannot be inferred and must be specified

V - the type of values in the returned OrderedMap; cannot be inferred and must be specified

Returns:

an empty OrderedMap with the given key and value types.