Package org.eclipse.jgit.lib

Class ObjectIdOwnerMap<V extends ObjectIdOwnerMap.Entry>

  • Type Parameters:
    V - type of subclass of ObjectId that will be stored in the map.
    All Implemented Interfaces:
    Iterable<V>, ObjectIdSet
    public class ObjectIdOwnerMap<V extends ObjectIdOwnerMap.Entry>
extends Object
implements Iterable<V>, ObjectIdSet
    Fast, efficient map for ObjectId subclasses in only one map.

    To use this map type, applications must have their entry value type extend from ObjectIdOwnerMap.Entry, which itself extends from ObjectId.

    Object instances may only be stored in ONE ObjectIdOwnerMap. This restriction exists because the map stores internal map state within each object instance. If an instance is be placed in another ObjectIdOwnerMap it could corrupt one or both map's internal state.

    If an object instance must be in more than one map, applications may use ObjectIdOwnerMap for one of the maps, and ObjectIdSubclassMap for the other map(s). It is encouraged to use ObjectIdOwnerMap for the map that is accessed most often, as this implementation runs faster than the more general ObjectIdSubclassMap implementation.

    • Constructor Detail

      • ObjectIdOwnerMap

        public ObjectIdOwnerMap()
        Create an empty map.

    • Method Detail

      • clear

        public void clear()
        Remove all entries from this map.

      • get

        public V get​(AnyObjectId toFind)
        Lookup an existing mapping.
        Parameters:
        toFind - the object identifier to find.
        Returns:
        the instance mapped to toFind, or null if no mapping exists.

      • contains

        public boolean contains​(AnyObjectId toFind)
        Returns true if the objectId is contained within the collection.

        Returns true if this map contains the specified object.

        Specified by:
        contains in interface ObjectIdSet
        Parameters:
        toFind - the objectId to find
        Returns:
        whether the collection contains the objectId.

      • add

        public <Q extends V> void add​(Q newValue)
        Store an object for future lookup.

        An existing mapping for must not be in this map. Callers must first call get(AnyObjectId) to verify there is no current mapping prior to adding a new mapping, or use addIfAbsent(Entry).

        Parameters:
        newValue - the object to store.

      • addIfAbsent

        public <Q extends V> V addIfAbsent​(Q newValue)
        Store an object for future lookup.

        Stores newValue, but only if there is not already an object for the same object name. Callers can tell if the value is new by checking the return value with reference equality: 

         V obj = ...;
 boolean wasNew = map.addIfAbsent(obj) == obj;
        Parameters:
        newValue - the object to store.
        Returns:
        newValue if stored, or the prior value already stored and that would have been returned had the caller used get(newValue) first.

      • size

        public int size()
        Get number of objects in this map.
        Returns:
        number of objects in this map.

      • isEmpty

        public boolean isEmpty()
        Whether this map is empty
        Returns:
        true if size() is 0.