MultiMap

Type Parameters:

K - the type of the map's keys

V - the type of the map's values

All Superinterfaces:

java.io.Serializable

All Known Implementing Classes:

ListMultiMap, SetMultiMap
```
public interface MultiMap<K,V>
extends java.io.Serializable
```
An interface for a multimap roughly conforming to Java's map specifications

Author:

Rob Rua (robrua@alumni.cmu.edu)

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`void`	`clear()` Removes all of the mappings from this map (optional operation).
`default java.util.Collection<V>`	`compute(K key, java.util.function.BiFunction<? super K,? super V,? extends V> remappingFunction)` Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).
`default java.util.Collection<V>`	`computeIfAbsent(K key, java.util.function.Function<? super K,? extends V> mappingFunction)` If the specified key is not already associated with a value (or is mapped to null), attempts to compute its value using the given mapping function and enters it into this map unless null.
`default java.util.Collection<V>`	`computeIfPresent(K key, java.util.function.BiFunction<? super K,? super V,? extends V> remappingFunction)` If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value.
`boolean`	`containsKey(java.lang.Object key)` Returns true if this map contains a mapping for the specified key.
`boolean`	`containsValue(java.lang.Object value)` Returns true if this map maps one or more keys to the specified value.
`java.util.Collection<java.util.Map.Entry<K,V>>`	`entries()` Returns a collection view of the mappings contained in this map.
`default void`	`forEach(java.util.function.BiConsumer<? super K,? super V> action)` Performs the given action for each entry in this map until all entries have been processed or the action throws an exception.
`java.util.Collection<V>`	`get(java.lang.Object key)` Returns the values to which the specified key is mapped, or null if this map contains no mapping for the key.
`java.util.Collection<V>`	`getEmptyCollection()` Provides an empty collection of the appropriate type to hold values.
`default java.util.Collection<V>`	`getOrDefault(java.lang.Object key, java.util.Collection<V> defaultValues)` Returns the values to which the specified key is mapped, or defaultValues if this map contains no mapping for the key.
`boolean`	`isEmpty()` Returns true if this map contains no key-value mappings.
`java.util.Set<K>`	`keySet()` Returns a set view of the keys contained in this map.
`default java.util.Collection<V>`	`merge(K key, V value, java.util.function.BiFunction<? super V,? super V,? extends V> remappingFunction)` If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value.
`void`	`put(K key, java.util.Collection<V> values)` Associates the specified values with the specified key in this map (optional operation).
`void`	`put(K key, V value)` Associates the specified value with the specified key in this map (optional operation).
`void`	`putAll(java.util.Map<? extends K,? extends V> map)` Copies all of the mappings from the specified map to this map (optional operation).
`void`	`putAll(MultiMap<? extends K,? extends V> map)` Copies all of the mappings from the specified multimap to this map (optional operation).
`default void`	`putIfAbsent(K key, java.util.Collection<V> values)` If the specified key is not already associated with a value (or is mapped to null) associates it with the given values and returns null, else returns the current value.
`default void`	`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.
`java.util.Collection<V>`	`remove(java.lang.Object key)` Removes the mapping for a key from this map if it is present (optional operation).
`default boolean`	`remove(java.lang.Object key, java.util.Collection<java.lang.Object> values)` Removes the entry for the specified key only if it is currently mapped to the specified values.
`default java.util.Collection<V>`	`replace(K key, java.util.Collection<V> values)` Replaces all existing entries for the specified key only if it is currently mapped to some value.
`default boolean`	`replace(K key, java.util.Collection<V> oldValues, java.util.Collection<V> newValues)` Replaces all entries for the specified key only if currently mapped to the specified values.
`default java.util.Collection<V>`	`replace(K key, V value)` Replaces all existing entries for the specified key only if it is currently mapped to some value.
`default boolean`	`replace(K key, V oldValue, V newValue)` Replaces a single entry for the specified key only if currently mapped to the specified value.
`default void`	`replaceAll(java.util.function.BiFunction<? super K,? super V,? extends V> function)` Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.
`int`	`size()` Returns the number of key-value mappings in this map.
`java.util.Collection<V>`	`values()` Returns a collection view of the values contained in this map.

- Method Detail
  - clear
```
void clear()
```
    Removes all of the mappings from this map (optional operation).
  - compute
```
default java.util.Collection<V> compute(K key,
                                        java.util.function.BiFunction<? super K,? super V,? extends V> remappingFunction)
```
    Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).
    
    Parameters:
    
    key - key with which the specified value is to be associated
    
    remappingFunction - the function to compute a value
    
    Returns:
    
    the new values associated with the specified key, or null if none
  - computeIfAbsent
```
default java.util.Collection<V> computeIfAbsent(K key,
                                                java.util.function.Function<? super K,? extends V> mappingFunction)
```
    If the specified key is not already associated with a value (or is mapped to null), attempts to compute its value using the given mapping function and enters it into this map unless null.
    
    Parameters:
    
    key - key with which the specified value is to be associated
    
    mappingFunction - the function to compute a value
    
    Returns:
    
    the current (existing or computed) values associated with the specified key, or null if the computed value is null
  - computeIfPresent
```
default java.util.Collection<V> computeIfPresent(K key,
                                                 java.util.function.BiFunction<? super K,? super V,? extends V> remappingFunction)
```
    If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value.
    
    Parameters:
    
    key - key with which the specified value is to be associated
    
    remappingFunction - the function to compute a value
    
    Returns:
    
    the new values associated with the specified key, or null if none
  - containsKey
```
boolean containsKey(java.lang.Object key)
```
    Returns true if this map contains a mapping for the specified key.
    
    Parameters:
    
    key - key whose presence in this map is to be tested
    
    Returns:
    
    true if this map contains a mapping for the specified key
  - containsValue
```
boolean containsValue(java.lang.Object value)
```
    Returns true if this map maps one or more keys to the specified value.
    
    Parameters:
    
    value - value whose presence in this map is to be tested
    
    Returns:
    
    true if this map maps one or more keys to the specified value
  - entries
```
java.util.Collection<java.util.Map.Entry<K,V>> entries()
```
    Returns a collection view of the mappings contained in this map.
    
    Returns:
    
    a collection view of the mappings contained in this map
  - forEach
```
default void forEach(java.util.function.BiConsumer<? super K,? super V> action)
```
    Performs the given action for each entry in this map until all entries have been processed or the action throws an exception.
    
    Parameters:
    
    action - The action to be performed for each entry
  - get
```
java.util.Collection<V> get(java.lang.Object key)
```
    Returns the values to which the specified key is mapped, or null if this map contains no mapping for the key.
    
    Parameters:
    
    key - the key to get values for
    
    Returns:
    
    the values to which the specified key is mapped, or null if this map contains no mapping for the key
  - getEmptyCollection
```
java.util.Collection<V> getEmptyCollection()
```
    Provides an empty collection of the appropriate type to hold values.
    
    Returns:
    
    an empty collection
  - getOrDefault
```
default java.util.Collection<V> getOrDefault(java.lang.Object key,
                                             java.util.Collection<V> defaultValues)
```
    Returns the values to which the specified key is mapped, or defaultValues if this map contains no mapping for the key.
    
    Parameters:
    
    key - the key whose associated values are to be returned
    
    defaultValues - the default mapping of the key
    
    Returns:
    
    the values to which the specified key is mapped, or defaultValue if this map contains no mapping for the key
  - isEmpty
```
boolean isEmpty()
```
    Returns true if this map contains no key-value mappings.
    
    Returns:
    
    true if this map contains no key-value mappings
  - keySet
```
java.util.Set<K> keySet()
```
    Returns a set view of the keys contained in this map.
    
    Returns:
    
    a set view of the keys contained in this map
  - merge
```
default java.util.Collection<V> merge(K key,
                                      V value,
                                      java.util.function.BiFunction<? super V,? super V,? extends V> remappingFunction)
```
    If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value.
    
    Parameters:
    
    key - key with which the resulting value is to be associated
    
    value - the non-null value to be merged with the existing values associated with the key or, if no existing value or a null value is associated with the key, to be associated with the key
    
    remappingFunction - the function to recompute a value if present
    
    Returns:
    
    the new values associated with the specified key, or null if no value is associated with the key
  - put
```
void put(K key,
         java.util.Collection<V> values)
```
    Associates the specified values with the specified key in this map (optional operation).
    
    Parameters:
    
    key - key with which the specified value is to be associated
    
    values - values to be associated with the specified key
  - put
```
void put(K key,
         V value)
```
    Associates the specified value with the specified key in this map (optional operation).
    
    Parameters:
    
    key - key with which the specified value is to be associated
    
    value - value to be associated with the specified key
  - putAll
```
void putAll(java.util.Map<? extends K,? extends V> map)
```
    Copies all of the mappings from the specified map to this map (optional operation).
    
    Parameters:
    
    map - mappings to be stored in this map
  - putAll
```
void putAll(MultiMap<? extends K,? extends V> map)
```
    Copies all of the mappings from the specified multimap to this map (optional operation).
    
    Parameters:
    
    map - mappings to be stored in this map
  - putIfAbsent
```
default void putIfAbsent(K key,
                         java.util.Collection<V> values)
```
    If the specified key is not already associated with a value (or is mapped to null) associates it with the given values and returns null, else returns the current value.
    
    Parameters:
    
    key - key with which the specified value is to be associated
    
    values - values to be associated with the specified key
  - putIfAbsent
```
default void 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.
    
    Parameters:
    
    key - key with which the specified value is to be associated
    
    value - value to be associated with the specified key
  - remove
```
java.util.Collection<V> remove(java.lang.Object key)
```
    Removes the mapping for a key from this map if it is present (optional operation).
    
    Parameters:
    
    key - key whose mappings are to be removed from the map
    
    Returns:
    
    the previous values associated with key, or null if there was no mapping for key.
  - remove
```
default boolean remove(java.lang.Object key,
                       java.util.Collection<java.lang.Object> values)
```
    Removes the entry for the specified key only if it is currently mapped to the specified values.
    
    Parameters:
    
    key - key with which the specified value is associated
    
    values - values expected to be associated with the specified key
    
    Returns:
    
    true if the value was removed
  - replace
```
default java.util.Collection<V> replace(K key,
                                        java.util.Collection<V> values)
```
    Replaces all existing entries for the specified key only if it is currently mapped to some value.
    
    Parameters:
    
    key - key with which the specified value is associated
    
    values - values to be associated with the specified key
    
    Returns:
    
    the previous values 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, if the implementation supports null values.)
  - replace
```
default boolean replace(K key,
                        java.util.Collection<V> oldValues,
                        java.util.Collection<V> newValues)
```
    Replaces all entries for the specified key only if currently mapped to the specified values.
    
    Parameters:
    
    key - key with which the specified values are associated
    
    oldValues - values expected to be associated with the specified key
    
    newValues - values to be associated with the specified key
    
    Returns:
    
    true if the values were replaced
  - replace
```
default java.util.Collection<V> replace(K key,
                                        V value)
```
    Replaces all existing entries for the specified key only if it is currently mapped to some value.
    
    Parameters:
    
    key - key with which the specified value is associated
    
    value - value to be associated with the specified key
    
    Returns:
    
    the previous values 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, if the implementation supports null values.)
  - replace
```
default boolean replace(K key,
                        V oldValue,
                        V newValue)
```
    Replaces a single entry for the specified key only if currently mapped to the specified value.
    
    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
  - replaceAll
```
default void replaceAll(java.util.function.BiFunction<? super K,? super V,? extends V> function)
```
    Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.
    
    Parameters:
    
    function - the function to apply to each entry
  - size
```
int size()
```
    Returns the number of key-value mappings in this map.
    
    Returns:
    
    the number of key-value mappings in this map
  - values
```
java.util.Collection<V> values()
```
    Returns a collection view of the values contained in this map.
    
    Returns:
    
    a collection view of the values contained in this map

Interface MultiMap<K,V>

Method Summary

Method Detail

clear

compute

computeIfAbsent

computeIfPresent

containsKey

containsValue

entries

forEach

get

getEmptyCollection

getOrDefault

isEmpty

keySet

merge

put

put

putAll

putAll

putIfAbsent

putIfAbsent

remove

remove

replace

replace

replace

replace

replaceAll

size

values