Package org.matsim.core.utils.collections

Class MapUtils

java.lang.Object

org.matsim.core.utils.collections.MapUtils

public final class MapUtils
extends Object

Utils class for the common pattern of creating an entry in a map if nothing is associated to the requested key. This is typically useful for weights or counters (Double or Integer), or one-to-many mappings (Lists or Sets).

Author:

thibautd

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	MapUtils.DefaultFactory<T>	Helper class, to use as a factory if objects should be instanciated using their parameter-less constructor.
static interface	MapUtils.Factory<T>

Method Summary

Modifier and Type	Method	Description
static <K> double	addToDouble(K key, Map<K,Double> map, double initialValue, double toAdd)	Add a given value to the Double associated with the key in this map, or initialize a new one if no mapping exists yet.
static <K> double	addToInteger(K key, Map<K,Integer> map, int initialValue, int toAdd)	Add a given value to the Integer associated with the key in this map, or initialize a new one if no mapping exists yet.
static <K,V> Collection<V>	get(Iterable<K> keys, Map<K,V> map)	Fill in a collection with the values associated with the requested keys
static <K,T> T	getArbitraryObject(K key, Map<K,T> map, MapUtils.Factory<T> fact)	Gets the object associated with the key in this map, or create one if no mapping exists yet.
static <K,V> Collection<V>	getCollection(K key, Map<K,Collection<V>> map)	Gets the collection associated with the key in this map, or create an empty list if no mapping exists yet.
static <K> Double	getDouble(K key, Map<K,Double> map, double initialValue)	Gets the double associated with the key in this map, or create a new one if no mapping exists yet.
static <K> Integer	getInteger(K key, Map<K,Integer> map, int initialValue)	Gets the Integer associated with the key in this map, or create a new one if no mapping exists yet.
static <K,V> List<V>	getList(K key, Map<K,List<V>> map)	Gets the collection associated with the key in this map, or create an empty list if no mapping exists yet.
static <K,C,V> Map<C,V>	getMap(K key, Map<K,Map<C,V>> map)	Gets the map associated with the key in this map, or create an empty map if no mapping exists yet.
static <K,V> Set<V>	getSet(K key, Map<K,Set<V>> map)	Gets the set associated with the key in this map, or create an empty set if no mapping exists yet.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getCollection

public static <K,V> Collection<V> getCollection(K key,
                                                      Map<K,Collection<V>> map)

Gets the collection associated with the key in this map, or create an empty list if no mapping exists yet.

Type Parameters:

K - type of the key

V - parameter of the collection type

Parameters:

key - the key of the mapping

map - the map in which to search

Returns:

the collection (evt. newly) associated with the key

getList

public static <K,V> List<V> getList(K key,
                                          Map<K,List<V>> map)

Gets the collection associated with the key in this map, or create an empty list if no mapping exists yet.

Type Parameters:

K - type of the key

V - parameter of the List type

Parameters:

key - the key of the mapping

map - the map in which to search

Returns:

the List (evt. newly) associated with the key

getSet

public static <K,V> Set<V> getSet(K key,
                                        Map<K,Set<V>> map)

Gets the set associated with the key in this map, or create an empty set if no mapping exists yet.

Type Parameters:

K - type of the key

V - parameter of the set type

Parameters:

key - the key of the mapping

map - the map in which to search

Returns:

the set (evt. newly) associated with the key

getMap

public static <K,C,V> Map<C,V> getMap(K key,
                                                        Map<K,Map<C,V>> map)

Gets the map associated with the key in this map, or create an empty map if no mapping exists yet.

Type Parameters:

K - type of the in the primary map

C - type of the key in the secondary map

V - type of the values in the secondary map

Parameters:

key - the key of the mapping

map - the map in which to search

Returns:

the Map (evt. newly) associated with the key

getArbitraryObject

public static <K,T> T getArbitraryObject(K key,
                                               Map<K,T> map,
                                               MapUtils.Factory<T> fact)

Gets the object associated with the key in this map, or create one if no mapping exists yet.

Type Parameters:

K - type of the key

T - parameter of the values type

Parameters:

key - the key of the mapping

map - the map in which to search

fact - the factory to use to create a default object if none is found

Returns:

the Object (evt. newly) associated with the key

getDouble

public static <K> Double getDouble(K key,
                                   Map<K,Double> map,
                                   double initialValue)

Gets the double associated with the key in this map, or create a new one if no mapping exists yet.

Type Parameters:

K - type of the key

Parameters:

key - the key of the mapping

map - the map in which to search

initialValue - the value to which new entries should be initialized

Returns:

the value (evt. newly) associated with the key

addToDouble

public static <K> double addToDouble(K key,
                                     Map<K,Double> map,
                                     double initialValue,
                                     double toAdd)

Add a given value to the Double associated with the key in this map, or initialize a new one if no mapping exists yet.

Type Parameters:

K - type of the key

Parameters:

key - the key of the mapping

map - the map in which to search

initialValue - the value to which new entries should be initialized

toAdd - the value to add to the existing mapped values

Returns:

the collection (evt. newly) associated with the key

getInteger

public static <K> Integer getInteger(K key,
                                     Map<K,Integer> map,
                                     int initialValue)

Gets the Integer associated with the key in this map, or create a new one if no mapping exists yet.

Type Parameters:

K - type of the key

Parameters:

key - the key of the mapping

map - the map in which to search

initialValue - the value to which new entries should be initialized

Returns:

the value (evt. newly) associated with the key

addToInteger

public static <K> double addToInteger(K key,
                                      Map<K,Integer> map,
                                      int initialValue,
                                      int toAdd)

Add a given value to the Integer associated with the key in this map, or initialize a new one if no mapping exists yet.

Type Parameters:

K - type of the key

Parameters:

key - the key of the mapping

map - the map in which to search

initialValue - the value to which new entries should be initialized

toAdd - the value to add to the existing mapped values

Returns:

the collection (evt. newly) associated with the key

get

public static <K,V> Collection<V> get(Iterable<K> keys,
                                            Map<K,V> map)

Fill in a collection with the values associated with the requested keys

Type Parameters:

K - type of the key

V - type of the values

Parameters:

keys - the keys to search for. If a key appears several times, its value will be added to the collection the corresponding number of times.

map - the map in which to search

Returns:

a new collection, filled in with the values associated with the keys provided, in iteration order.