java.lang.Object
java.util.AbstractMap<K,V>
org.datanucleus.store.types.wrappers.Map<K,V>
org.datanucleus.store.types.wrappers.backed.Map<K,V>
All Implemented Interfaces:
Serializable, Cloneable, Map<K,V>, SCO<Map<K,V>>, SCOContainer<Map<K,V>>, SCOMap<Map<K,V>,K,V>, BackedSCO

public class Map<K,V> extends Map<K,V> implements BackedSCO
A mutable second-class Map object. Uses a "delegate" as a local store for the Map. Uses a "backing store" (SetStore) to represent the datastore. The "delegate" is updated with the "backing store" information at necessary intervals.

Modes of Operation

The user can operate the map in 2 modes. The cached mode will use an internal cache of the elements (in the "delegate") reading them at the first opportunity and then using the cache thereafter. The non-cached mode will just go direct to the "backing store" each call.

Mutators

When the backing store is present any updates are passed direct to the datastore as well as to the "delegate". If the "backing store" isn't present the changes are made to the "delegate" only.

Accessors

When any accessor method is invoked, it typically checks whether the map has been loaded from its backing store and does this as necessary. Some methods (size(), containsKey()) just check if everything is loaded and use the delegate if possible, otherwise going direct to the datastore.
See Also:
  • Field Details

    • allowNulls

      protected transient boolean allowNulls
    • backingStore

      protected transient MapStore<K,V> backingStore
    • useCache

      protected transient boolean useCache
    • isCacheLoaded

      protected transient boolean isCacheLoaded
  • Constructor Details

    • Map

      public Map(DNStateManager sm, AbstractMemberMetaData mmd)
      Constructor, using StateManager of the "owner" and the field name.
      Parameters:
      sm - The owner StateManager
      mmd - Metadata for the member
  • Method Details

    • initialise

      public void initialise(Map newValue, Object oldValue)
      Description copied from interface: SCO
      Method to initialise the SCO for use, where replacing an old value with a new value such as when calling a setter field passing in a new value. Note that oldValue is marked as Object since for cases where the member type is Collection the newValue could be, for example, ArrayList, and the oldValue of type Collection (representing null).
      Specified by:
      initialise in interface SCO<K>
      Overrides:
      initialise in class Map<K,V>
      Parameters:
      newValue - New value (to wrap)
      oldValue - Old value (to use in deciding what needs deleting etc)
    • initialise

      public void initialise(Map m)
      Method to initialise the SCO from an existing value.
      Specified by:
      initialise in interface SCO<K>
      Overrides:
      initialise in class Map<K,V>
      Parameters:
      m - The object to set from
    • initialise

      public void initialise()
      Method to initialise the SCO for use.
      Specified by:
      initialise in interface SCO<K>
      Overrides:
      initialise in class Map<K,V>
    • getValue

      public Map getValue()
      Accessor for the unwrapped value that we are wrapping.
      Specified by:
      getValue in interface SCO<K>
      Overrides:
      getValue in class Map<K,V>
      Returns:
      The unwrapped value
    • load

      public void load()
      Method to effect the load of the data in the SCO. Used when the SCO supports lazy-loading to tell it to load all now.
      Specified by:
      load in interface SCOContainer<K>
      Overrides:
      load in class Map<K,V>
    • isLoaded

      public boolean isLoaded()
      Method to return if the SCO has its contents loaded. If the SCO doesn't support lazy loading will just return true.
      Specified by:
      isLoaded in interface BackedSCO
      Specified by:
      isLoaded in interface SCOContainer<K>
      Overrides:
      isLoaded in class Map<K,V>
      Returns:
      Whether it is loaded
    • loadFromStore

      protected void loadFromStore()
      Method to load all elements from the "backing store" where appropriate.
    • getBackingStore

      public Store getBackingStore()
      Specified by:
      getBackingStore in interface BackedSCO
    • updateEmbeddedKey

      public void updateEmbeddedKey(K key, int fieldNumber, Object newValue, boolean makeDirty)
      Method to update an embedded key in this map.
      Specified by:
      updateEmbeddedKey in interface SCOMap<Map<K,V>,K,V>
      Overrides:
      updateEmbeddedKey in class Map<K,V>
      Parameters:
      key - The key
      fieldNumber - Number of field in the key
      newValue - New value for this field
      makeDirty - Whether to make the SCO field dirty.
    • updateEmbeddedValue

      public void updateEmbeddedValue(V value, int fieldNumber, Object newValue, boolean makeDirty)
      Method to update an embedded value in this map.
      Specified by:
      updateEmbeddedValue in interface SCOMap<Map<K,V>,K,V>
      Overrides:
      updateEmbeddedValue in class Map<K,V>
      Parameters:
      value - The value
      fieldNumber - Number of field in the value
      newValue - New value for this field
      makeDirty - Whether to make the SCO field dirty.
    • unsetOwner

      public void unsetOwner()
      Method to unset the owner and field information.
      Specified by:
      unsetOwner in interface SCO<K>
      Overrides:
      unsetOwner in class Map<K,V>
    • clone

      public Object clone()
      Creates and returns a copy of this object.

      Mutable second-class Objects are required to provide a public clone method in order to allow for copying persistable objects. In contrast to Object.clone(), this method must not throw a CloneNotSupportedException.

      Specified by:
      clone in interface SCO<K>
      Overrides:
      clone in class Map<K,V>
      Returns:
      Clone of the object
    • containsKey

      public boolean containsKey(Object key)
      Utility to check if a key is contained in the Map.
      Specified by:
      containsKey in interface Map<K,V>
      Overrides:
      containsKey in class Map<K,V>
      Parameters:
      key - The key to check
      Returns:
      Whether it is contained
    • containsValue

      public boolean containsValue(Object value)
      Utility to check if a value is contained in the Map.
      Specified by:
      containsValue in interface Map<K,V>
      Overrides:
      containsValue in class Map<K,V>
      Parameters:
      value - The value to check
      Returns:
      Whether it is contained
    • entrySet

      public Set entrySet()
      Accessor for the set of entries in the Map.
      Specified by:
      entrySet in interface Map<K,V>
      Overrides:
      entrySet in class Map<K,V>
      Returns:
      Set of entries
    • equals

      public boolean equals(Object o)
      Method to check the equality of this map, and another.
      Specified by:
      equals in interface Map<K,V>
      Overrides:
      equals in class Map<K,V>
      Parameters:
      o - The map to compare against.
      Returns:
      Whether they are equal.
    • forEach

      public void forEach(BiConsumer<? super K,? super V> action)
      Specified by:
      forEach in interface Map<K,V>
      Overrides:
      forEach in class Map<K,V>
    • get

      public V get(Object key)
      Accessor for the value stored against a key.
      Specified by:
      get in interface Map<K,V>
      Overrides:
      get in class Map<K,V>
      Parameters:
      key - The key
      Returns:
      The value.
    • hashCode

      public int hashCode()
      Method to generate a hashcode for this Map.
      Specified by:
      hashCode in interface Map<K,V>
      Overrides:
      hashCode in class Map<K,V>
      Returns:
      The hashcode.
    • isEmpty

      public boolean isEmpty()
      Method to return if the Map is empty.
      Specified by:
      isEmpty in interface Map<K,V>
      Overrides:
      isEmpty in class Map<K,V>
      Returns:
      Whether it is empty.
    • keySet

      public Set keySet()
      Accessor for the set of keys in the Map.
      Specified by:
      keySet in interface Map<K,V>
      Overrides:
      keySet in class Map<K,V>
      Returns:
      Set of keys.
    • size

      public int size()
      Method to return the size of the Map.
      Specified by:
      size in interface Map<K,V>
      Overrides:
      size in class Map<K,V>
      Returns:
      The size
    • values

      public Collection values()
      Accessor for the set of values in the Map.
      Specified by:
      values in interface Map<K,V>
      Overrides:
      values in class Map<K,V>
      Returns:
      Set of values.
    • toString

      public String toString()
      Method to return a string form of this Map.
      Overrides:
      toString in class AbstractMap<K,V>
      Returns:
      String form of this Map.
    • clear

      public void clear()
      Method to clear the Map.
      Specified by:
      clear in interface Map<K,V>
      Overrides:
      clear in class Map<K,V>
    • put

      public V put(K key, V value)
      Method to add a value to the Map.
      Specified by:
      put in interface Map<K,V>
      Overrides:
      put in class Map<K,V>
      Parameters:
      key - The key for the value.
      value - The value
      Returns:
      The previous value against this key (if any).
    • putAll

      public void putAll(Map m)
      Method to add a Map of values to this map.
      Specified by:
      putAll in interface Map<K,V>
      Overrides:
      putAll in class Map<K,V>
      Parameters:
      m - The Map to add
    • remove

      public V remove(Object key)
      Method to remove a value from the Map.
      Specified by:
      remove in interface Map<K,V>
      Overrides:
      remove in class Map<K,V>
      Parameters:
      key - The key for the value.
      Returns:
      The value removed.
    • writeReplace

      protected Object writeReplace() throws ObjectStreamException
      The writeReplace method is called when ObjectOutputStream is preparing to write the object to the stream. The ObjectOutputStream checks whether the class defines the writeReplace method. If the method is defined, the writeReplace method is called to allow the object to designate its replacement in the stream. The object returned should be either of the same type as the object passed in or an object that when read and resolved will result in an object of a type that is compatible with all references to the object.
      Overrides:
      writeReplace in class Map<K,V>
      Returns:
      the replaced object
      Throws:
      ObjectStreamException - if an error occurs