| java.util.HashMap
 org.apache.commons.collections.MultiHashMap
| MultiHashMap | | public class MultiHashMap extends HashMap implements MultiMap(Code) | | MultiHashMap is the default implementation of the
org.apache.commons.collections.MultiMap MultiMap interface.
A MultiMap is a Map with slightly different semantics.
Putting a value into the map will add the value to a Collection at that key.
Getting a value will return a Collection, holding all the values put to that key.
This implementation uses an ArrayList as the collection.
The internal storage list is made available without cloning via the
get(Object) and entrySet() methods.
The implementation returns null when there are no values mapped to a key.
For example:
MultiMap mhm = new MultiHashMap();
mhm.put(key, "A");
mhm.put(key, "B");
mhm.put(key, "C");
List list = (List) mhm.get(key);
list will be a list containing "A", "B", "C".
since:
Commons Collections 2.0
version:
$Revision: 372373 $ $Date: 2006-01-26 00:10:43 +0000 (Thu, 26 Jan 2006) $
author:
Christopher Berry
author:
James Strachan
author:
Steve Downey
author:
Stephen Colebourne
author:
Julien Buret
author:
Serhiy Yevtushenko
author:
Robert Ribnitz |
| Constructor Summary | |
| public | MultiHashMap()
Constructor. | | public | MultiHashMap(int initialCapacity)
Constructor. | | public | MultiHashMap(int initialCapacity, float loadFactor)
Constructor. | | public | MultiHashMap(Map mapToCopy)
Constructor that copies the input map creating an independent copy.
This method performs different behaviour depending on whether the map
specified is a MultiMap or not. |
| MultiHashMap | | public MultiHashMap()(Code) | | Constructor.
|
| MultiHashMap | | public MultiHashMap(int initialCapacity)(Code) | | Constructor.
Parameters:
initialCapacity - the initial map capacity |
| MultiHashMap | | public MultiHashMap(int initialCapacity, float loadFactor)(Code) | | Constructor.
Parameters:
initialCapacity - the initial map capacity
Parameters:
loadFactor - the amount 0.0-1.0 at which to resize the map |
| MultiHashMap | | public MultiHashMap(Map mapToCopy)(Code) | | Constructor that copies the input map creating an independent copy.
This method performs different behaviour depending on whether the map
specified is a MultiMap or not. If a MultiMap is specified, each internal
collection is also cloned. If the specified map only implements Map, then
the values are not cloned.
NOTE: From Commons Collections 3.1 this method correctly copies a MultiMap
to form a truly independent new map.
NOTE: From Commons Collections 3.2 this method delegates to the newly
added putAll(Map) override method.
Parameters:
mapToCopy - a Map to copy |
| clear | | public void clear()(Code) | | Clear the map.
This clears each collection in the map, and so may be slow.
|
| clone | | public Object clone()(Code) | | Clones the map creating an independent copy.
The clone will shallow clone the collections as well as the map.
the cloned map |
| containsValue | | public boolean containsValue(Object value)(Code) | | Checks whether the map contains the value specified.
This checks all collections against all keys for the value, and thus could be slow.
Parameters:
value - the value to search for true if the map contains the value |
| containsValue | | public boolean containsValue(Object key, Object value)(Code) | | Checks whether the collection at the specified key contains the value.
Parameters:
value - the value to search for true if the map contains the value
since:
Commons Collections 3.1 |
| createCollection | | protected Collection createCollection(Collection coll)(Code) | | Creates a new instance of the map value Collection container.
This method can be overridden to use your own collection type.
Parameters:
coll - the collection to copy, may be null the new collection |
| getCollection | | public Collection getCollection(Object key)(Code) | | Gets the collection mapped to the specified key.
This method is a convenience method to typecast the result of get(key).
Parameters:
key - the key to retrieve the collection mapped to the key, null if no mapping
since:
Commons Collections 3.1 |
| iterator | | public Iterator iterator(Object key)(Code) | | Gets an iterator for the collection mapped to the specified key.
Parameters:
key - the key to get an iterator for the iterator of the collection at the key, empty iterator if key not in map
since:
Commons Collections 3.1 |
| put | | public Object put(Object key, Object value)(Code) | | Adds the value to the collection associated with the specified key.
Unlike a normal Map the previous value is not replaced.
Instead the new value is added to the collection stored against the key.
Parameters:
key - the key to store against
Parameters:
value - the value to add to the collection at the key the value added if the map changed and null if the map did not change |
| putAll | | public void putAll(Map map)(Code) | | Override superclass to ensure that MultiMap instances are
correctly handled.
NOTE: Prior to version 3.2, putAll(map) did not work properly
when passed a MultiMap.
Parameters:
map - the map to copy (either a normal or multi map) |
| putAll | | public boolean putAll(Object key, Collection values)(Code) | | Adds a collection of values to the collection associated with the specified key.
Parameters:
key - the key to store against
Parameters:
values - the values to add to the collection at the key, null ignored true if this map changed
since:
Commons Collections 3.1 |
| remove | | public Object remove(Object key, Object item)(Code) | | Removes a specific value from map.
The item is removed from the collection mapped to the specified key.
Other values attached to that key are unaffected.
If the last value for a key is removed, null will be returned
from a subsequant get(key).
Parameters:
key - the key to remove from
Parameters:
item - the value to remove the value removed (which was passed in), null if nothing removed |
| size | | public int size(Object key)(Code) | | Gets the size of the collection mapped to the specified key.
Parameters:
key - the key to get size for the size of the collection at the key, zero if key not in map
since:
Commons Collections 3.1 |
| superValuesIterator | | Iterator superValuesIterator()(Code) | | Gets the values iterator from the superclass, as used by inner class.
iterator |
| totalSize | | public int totalSize()(Code) | | Gets the total size of the map by counting all the values.
the total size of the map counting all values
since:
Commons Collections 3.1 |
| values | | public Collection values()(Code) | | Gets a collection containing all the values in the map.
This returns a collection containing the combination of values from all keys.
a collection view of the values contained in this map |
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