uk.ac.starlink.util
Class MapGroup

java.lang.Object
  extended byuk.ac.starlink.util.MapGroup
Direct Known Subclasses:
ValueInfoMapGroup

public class MapGroup
extends Object

Represents an ordered list of Maps containing related data. The same keys may crop up in the maps comprising the groups, and are taken to have the same meaning, so that all the values associated with a given key in any of the maps in the group are taken to be a related set. There is no requirement however that a key which appears in one of the maps has to appear in any or all of the others. A single list of the union of all the keys which appear in any of the maps in the group can be obtained. An ordering may be imposed on this list.


Constructor Summary
MapGroup()
          Constructs a new MapGroup.
 
Method Summary
 void addMap(Map map)
          Adds a new Map to the end of this group.
 List getKeyOrder()
          Returns the list which defines ordering for any keys which crop up.
 List getKnownKeys()
          Returns a list of all the keys which appear in any of the metadata sets.
 List getMaps()
          Returns an unmodifiable list of all the maps in this group.
 void removeKey(Object key)
          Removes all entries with a given key for every map in this group.
 void removeKeys(Collection keys)
          Removes all entries which have a key in a given collection for every map in this group.
 void retainKeys(Collection keys)
          Removes all entries except those with keys in a given collection for every map in this group.
 void setKeyOrder(List ordering)
          Mandates an ordering to be imposed on the map keys.
 void setKnownKeys(List keys)
          Sets the list of known keys.
 int size()
          Returns the number of maps in this group.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

MapGroup

public MapGroup()
Constructs a new MapGroup.

Method Detail

addMap

public void addMap(Map map)
Adds a new Map to the end of this group.

Parameters:
map - the map to add

getMaps

public List getMaps()
Returns an unmodifiable list of all the maps in this group. It is unmodifiable so that you can't put anything in it which is not a Map.

Returns:
a list of the maps

size

public int size()
Returns the number of maps in this group.

Returns:
map count

setKeyOrder

public void setKeyOrder(List ordering)
Mandates an ordering to be imposed on the map keys. The effect of this call is to influence the order of the list returned by subsequent calls of getKnownKeys().

The supplied argument ordering is a list of objects; an object which appears earlier in this list is considered to be earlier in the list of MapGroup keys. Any which do not appear in this list will be ranked in an unspecified order at the end (their natural comparison order will be used if both objects implement Comparable).

Parameters:
ordering - a list of objects which may appear in this group's map keys

getKeyOrder

public List getKeyOrder()
Returns the list which defines ordering for any keys which crop up.

Returns:
current key ordering

removeKeys

public void removeKeys(Collection keys)
Removes all entries which have a key in a given collection for every map in this group.

Parameters:
keys - the set of key values whose entries must be removed

removeKey

public void removeKey(Object key)
Removes all entries with a given key for every map in this group.

Parameters:
key - the key whose entries must be removed

retainKeys

public void retainKeys(Collection keys)
Removes all entries except those with keys in a given collection for every map in this group.

Parameters:
keys - the keys whose entries must be retained

setKnownKeys

public void setKnownKeys(List keys)
Sets the list of known keys. This list, if not null, will be returned by subsequent calls of getKnownKeys().

Parameters:
keys - collection of keys

getKnownKeys

public List getKnownKeys()
Returns a list of all the keys which appear in any of the metadata sets. The order is determined by the most recent call of setKeyOrder(java.util.List). If it has never been called they will be returned in an arbitrary order. If setKnownKeys(java.util.List) has been called with a non-null argument, that list will be returned instead.

Returns:
the list of map keys

Copyright © 2004 CLRC: Central Laboratory of the Research Councils. All rights reserved.