org.apache.commons.collections.keyvalue
Class MultiKey
java.lang.Object
org.apache.commons.collections.keyvalue.MultiKey
- Serializable
public class MultiKey
extends java.lang.Object
implements Serializable
A
MultiKey
allows multiple map keys to be merged together.
The purpose of this class is to avoid the need to write code to handle
maps of maps. An example might be the need to lookup a filename by
key and locale. The typical solution might be nested maps. This class
can be used instead by creating an instance passing in the key and locale.
Example usage:
// populate map with data mapping key+locale to localizedText
Map map = new HashMap();
MultiKey multiKey = new MultiKey(key, locale);
map.put(multiKey, localizedText);
// later retireve the localized text
MultiKey multiKey = new MultiKey(key, locale);
String localizedText = (String) map.get(multiKey);
$Revision: 1.5 $ $Date: 2004/03/13 12:43:43 $- Howard Lewis Ship
- Stephen Colebourne
MultiKey(Object key1, Object key2) - Constructor taking two keys.
|
MultiKey(Object key1, Object key2, Object key3) - Constructor taking three keys.
|
MultiKey(Object key1, Object key2, Object key3, Object key4) - Constructor taking four keys.
|
MultiKey(Object key1, Object key2, Object key3, Object key4, Object key5) - Constructor taking five keys.
|
MultiKey(Object[] keys) - Constructor taking an array of keys which is cloned.
|
MultiKey(Object[] keys, boolean makeClone) - Constructor taking an array of keys, optionally choosing whether to clone.
|
boolean | equals(Object other) - Compares this object to another.
|
Object | getKey(int index) - Gets the key at the specified index.
|
Object[] | getKeys() - Gets a clone of the array of keys.
|
int | hashCode() - Gets the combined hash code that is computed from all the keys.
|
int | size() - Gets the size of the list of keys.
|
String | toString() - Gets a debugging string version of the key.
|
MultiKey
public MultiKey(Object key1,
Object key2)
Constructor taking two keys.
The keys should be immutable
If they are not then they must not be changed after adding to the MultiKey.
key1
- the first keykey2
- the second key
MultiKey
public MultiKey(Object key1,
Object key2,
Object key3)
Constructor taking three keys.
The keys should be immutable
If they are not then they must not be changed after adding to the MultiKey.
key1
- the first keykey2
- the second keykey3
- the third key
MultiKey
public MultiKey(Object key1,
Object key2,
Object key3,
Object key4)
Constructor taking four keys.
The keys should be immutable
If they are not then they must not be changed after adding to the MultiKey.
key1
- the first keykey2
- the second keykey3
- the third keykey4
- the fourth key
MultiKey
public MultiKey(Object key1,
Object key2,
Object key3,
Object key4,
Object key5)
Constructor taking five keys.
The keys should be immutable
If they are not then they must not be changed after adding to the MultiKey.
key1
- the first keykey2
- the second keykey3
- the third keykey4
- the fourth keykey5
- the fifth key
MultiKey
public MultiKey(Object[] keys)
Constructor taking an array of keys which is cloned.
The keys should be immutable
If they are not then they must not be changed after adding to the MultiKey.
This is equivalent to
new MultiKey(keys, true)
.
keys
- the array of keys, not null
MultiKey
public MultiKey(Object[] keys,
boolean makeClone)
Constructor taking an array of keys, optionally choosing whether to clone.
If the array is not cloned, then it must not be modified.
This method is public for performance reasons only, to avoid a clone.
The hashcode is calculated once here in this method.
Therefore, changing the array passed in would not change the hashcode but
would change the equals method, which is a bug.
This is the only fully safe usage of this constructor, as the object array
is never made available in a variable:
new MultiKey(new Object[] {...}, false);
The keys should be immutable
If they are not then they must not be changed after adding to the MultiKey.
keys
- the array of keys, not nullmakeClone
- true to clone the array, false to assign it
equals
public boolean equals(Object other)
Compares this object to another.
To be equal, the other object must be a
MultiKey
with the
same number of keys which are also equal.
other
- the other object to compare to
getKey
public Object getKey(int index)
Gets the key at the specified index.
The key should be immutable.
If it is not then it must not be changed.
index
- the index to retrieve
getKeys
public Object[] getKeys()
Gets a clone of the array of keys.
The keys should be immutable
If they are not then they must not be changed.
hashCode
public int hashCode()
Gets the combined hash code that is computed from all the keys.
This value is computed once and then cached, so elements should not
change their hash codes once created (note that this is the same
constraint that would be used if the individual keys elements were
themselves
Map
keys.
size
public int size()
Gets the size of the list of keys.
- the size of the list of keys
toString
public String toString()
Gets a debugging string version of the key.
Copyright © 2001-2006 Apache Software Foundation. All Rights Reserved.