Package uk.ac.starlink.util
Class MapGroup
- java.lang.Object
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- uk.ac.starlink.util.MapGroup
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public class MapGroup extends java.lang.Object
Represents an ordered list ofMap
s 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.- Author:
- Mark Taylor (Starlink)
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Constructor Summary
Constructors Constructor Description MapGroup()
Constructs a new MapGroup.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
addMap(java.util.Map map)
Adds a new Map to the end of this group.java.util.List
getKeyOrder()
Returns the list which defines ordering for any keys which crop up.java.util.List
getKnownKeys()
Returns a list of all the keys which appear in any of the metadata sets.java.util.List
getMaps()
Returns an unmodifiable list of all the maps in this group.void
removeKey(java.lang.Object key)
Removes all entries with a given key for every map in this group.void
removeKeys(java.util.Collection keys)
Removes all entries which have a key in a given collection for every map in this group.void
retainKeys(java.util.Collection keys)
Removes all entries except those with keys in a given collection for every map in this group.void
setKeyOrder(java.util.List ordering)
Mandates an ordering to be imposed on the map keys.void
setKnownKeys(java.util.List keys)
Sets the list of known keys.int
size()
Returns the number of maps in this group.
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Method Detail
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addMap
public void addMap(java.util.Map map)
Adds a new Map to the end of this group.- Parameters:
map
- the map to add
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getMaps
public java.util.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
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size
public int size()
Returns the number of maps in this group.- Returns:
- map count
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setKeyOrder
public void setKeyOrder(java.util.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 ofgetKnownKeys()
.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
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getKeyOrder
public java.util.List getKeyOrder()
Returns the list which defines ordering for any keys which crop up.- Returns:
- current key ordering
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removeKeys
public void removeKeys(java.util.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
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removeKey
public void removeKey(java.lang.Object key)
Removes all entries with a given key for every map in this group.- Parameters:
key
- the key whose entries must be removed
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retainKeys
public void retainKeys(java.util.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
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setKnownKeys
public void setKnownKeys(java.util.List keys)
Sets the list of known keys. This list, if not null, will be returned by subsequent calls ofgetKnownKeys()
.- Parameters:
keys
- collection of keys
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getKnownKeys
public java.util.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 ofsetKeyOrder(java.util.List)
. If it has never been called they will be returned in an arbitrary order. IfsetKnownKeys(java.util.List)
has been called with a non-null argument, that list will be returned instead.- Returns:
- the list of map keys
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