org.jvnet.hk2.component
Class MultiMap<K,V>

java.lang.Object
  org.jvnet.hk2.component.MultiMap<K,V>

public final class MultiMap<K,V>
extends java.lang.Object

Map from a key to multiple values. Order is significant among values, and null values are allowed, although null keys are not.

Author:

Kohsuke Kawaguchi

Constructor Summary

MultiMap()
Creates an empty multi-map.

MultiMap(MultiMap<K,V> base)
Copy constructor.

Method Summary

void	add(K k, V v) Adds one more value.
MultiMap<K,V>	clone() Creates a copy of the map that contains the exact same key and value set.
boolean	containsKey(K key) Checks if the map contains the given key.
static <K,V> MultiMap<K,V>	emptyMap() Gets the singleton read-only empty multi-map.
java.util.Set<java.util.Map.Entry<K,java.util.List<V>>>	entrySet() Lists up all entries.
java.util.List<V>	get(K k)
V	getOne(K k) Gets the first value if any, or null.
void	set(K k, java.util.Collection<? extends V> v) Replaces all the existing values associated with the key by the given value.
void	set(K k, V v) Replaces all the existing values associated wit hthe key by the given single value.
int	size() Returns the size of the map
java.lang.String	toCommaSeparatedString() Format the map as "key=value1,key=value2,...."
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

MultiMap

public MultiMap()

Creates an empty multi-map.

MultiMap

public MultiMap(MultiMap<K,V> base)

Copy constructor.

Method Detail

toString

public final java.lang.String toString()

Overrides:

toString in class java.lang.Object

add

public final void add(K k,
                      V v)

Adds one more value.

set

public void set(K k,
                java.util.Collection<? extends V> v)

Replaces all the existing values associated with the key by the given value.

Parameters:

v - Can be null or empty.

set

public void set(K k,
                V v)

Replaces all the existing values associated wit hthe key by the given single value.

This is short for set(k,Collections.singleton(v))

get

public final java.util.List<V> get(K k)

Returns:

Can be empty but never null. Read-only.

containsKey

public boolean containsKey(K key)

Checks if the map contains the given key.

getOne

public final V getOne(K k)

Gets the first value if any, or null.

This is useful when you know the given key only has one value and you'd like to get to that value.

Returns:

null if the key has no values or it has a value but the value is null.

entrySet

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

Lists up all entries.

toCommaSeparatedString

public java.lang.String toCommaSeparatedString()

Format the map as "key=value1,key=value2,...."

clone

public MultiMap<K,V> clone()

Creates a copy of the map that contains the exact same key and value set. Keys and values won't cloned.

Overrides:

clone in class java.lang.Object

size

public int size()

Returns the size of the map

Returns:

integer or 0 if the map is empty

emptyMap

public static <K,V> MultiMap<K,V> emptyMap()

Gets the singleton read-only empty multi-map.

See Also:

Collections.emptyMap()