Package com.tangosol.util

Class SimpleMapEntry<K,V>

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.SimpleMapEntry<K,V>
All Implemented Interfaces:
InvocableMap.Entry<K,V>, MapTrigger.Entry<K,V>, QueryMap.Entry<K,V>, Serializable, Cloneable, Map.Entry<K,V>
Direct Known Subclasses:
AbstractKeyBasedMap.EntrySet.Entry, BinaryMap.Entry, InvocableMapHelper.SimpleEntry, SimpleElement.AttributeMap.Entry
public class SimpleMapEntry<K,V> extends Base implements MapTrigger.Entry<K,V>, Cloneable, Serializable
A map entry (key-value pair). The Map.entrySet method returns a collection-view of the map, whose elements are of this class. The only way to obtain a reference to a map entry is from the iterator of this collection-view. These Map.Entry objects are valid only for the duration of the iteration; more formally, the behavior of a map entry is undefined if the backing map has been modified after the entry was returned by the iterator, except through the iterator's own remove operation, or through the setValue operation on a map entry returned by the iterator.
Author:
cp 2002.02.07
See Also:

  • Field Details

    • NO_VALUE

      protected static final Object NO_VALUE
      Constant used to indicate that the original value does not exist.

    • m_oKey

      protected K m_oKey
      The key. This object reference will not change for the life of the Entry.

    • m_oValue

      protected V m_oValue
      The value. This object reference can change within the life of the Entry.

    • m_oOrigValue

      protected V m_oOrigValue
      The original value. This object reference will not change within the life of the Entry.

  • Constructor Details

    • SimpleMapEntry

      protected SimpleMapEntry()
      Default constructor.

    • SimpleMapEntry

      protected SimpleMapEntry(K key)
      Construct a SimpleMapEntry with just a key.
      Parameters:
      key - an object for the key

    • SimpleMapEntry

      public SimpleMapEntry(Map.Entry<K,V> entry)
      Copy constructor.
      Parameters:
      entry - an entry to copy from

    • SimpleMapEntry

      public SimpleMapEntry(K key, V value)
      Construct a SimpleMapEntry with a key and a value.
      Parameters:
      key - an object for the key
      value - an object for the value

    • SimpleMapEntry

      public SimpleMapEntry(K key, V value, V origValue)
      Construct a SimpleMapEntry with a key, value and original value.
      Parameters:
      key - an object for the key
      value - an object for the value
      origValue - an object for the original value
      Since:
      Coherence 3.6

  • Method Details

    • getKey

      public K getKey()
      Return the key corresponding to this entry. The resultant key does not necessarily exist within the containing Map, which is to say that InvocableMap.this.containsKey(getKey()) could return false. To test for the presence of this key within the Map, use InvocableMap.Entry.isPresent(), and to create the entry for the key, use InvocableMap.Entry.setValue(V).
      Specified by:
      getKey in interface InvocableMap.Entry<K,V>
      Specified by:
      getKey in interface Map.Entry<K,V>
      Returns:
      the key corresponding to this entry; may be null if the underlying Map supports null keys

    • getValue

      public V getValue()
      Returns the value corresponding to this entry. If the mapping has been removed from the backing map (by the iterator's remove operation), the results of this call are undefined.
      Specified by:
      getValue in interface InvocableMap.Entry<K,V>
      Specified by:
      getValue in interface Map.Entry<K,V>
      Returns:
      the value corresponding to this entry.

    • setValue

      public V setValue(V value)
      Replaces the value corresponding to this entry with the specified value (optional operation). (Writes through to the map.) The behavior of this call is undefined if the mapping has already been removed from the map (by the iterator's remove operation).
      Specified by:
      setValue in interface InvocableMap.Entry<K,V>
      Specified by:
      setValue in interface Map.Entry<K,V>
      Parameters:
      value - new value to be stored in this entry
      Returns:
      old value corresponding to the entry

    • getOriginalValue

      public V getOriginalValue()
      Determine the value that existed before the start of the mutating operation that is being evaluated by the trigger.
      Specified by:
      getOriginalValue in interface MapTrigger.Entry<K,V>
      Returns:
      the original value corresponding to this Entry; may be null if the value is null or if the Entry did not exist in the Map

    • isOriginalPresent

      public boolean isOriginalPresent()
      Determine whether or not the Entry existed before the start of the mutating operation that is being evaluated by the trigger.
      Specified by:
      isOriginalPresent in interface MapTrigger.Entry<K,V>
      Returns:
      true iff this Entry was existent in the containing Map

    • setValue

      public void setValue(V oValue, boolean fSynthetic)
      Store the value corresponding to this entry. If the entry does not exist, then the entry will be created by invoking this method, even with a null value (assuming the Map supports null values).

      Unlike the other form of setValue, this form does not return the previous value, and as a result may be significantly less expensive (in terms of cost of execution) for certain Map implementations.

      Specified by:
      setValue in interface InvocableMap.Entry<K,V>
      Parameters:
      oValue - the new value for this Entry
      fSynthetic - pass true only if the insertion into or modification of the Map should be treated as a synthetic event

    • update

      public <U> void update(ValueUpdater<V,U> updater, U value)
      Update the Entry's value. Calling this method is semantically equivalent to: 
         V target = entry.getValue();
   updater.update(target, value);
   entry.setValue(target, false);
      The benefit of using this method is that it may allow the Entry implementation to significantly optimize the operation, such as for purposes of delta updates and backup maintenance.
      Specified by:
      update in interface InvocableMap.Entry<K,V>
      Type Parameters:
      U - the class of the value
      Parameters:
      updater - a ValueUpdater used to modify the Entry's value
      value - the new value for this Entry

    • isPresent

      public boolean isPresent()
      Determine if this Entry exists in the Map. If the Entry is not present, it can be created by calling InvocableMap.Entry.setValue(Object) or InvocableMap.Entry.setValue(Object, boolean). If the Entry is present, it can be destroyed by calling InvocableMap.Entry.remove(boolean).
      Specified by:
      isPresent in interface InvocableMap.Entry<K,V>
      Returns:
      true iff this Entry is existent in the containing Map

    • isSynthetic

      public boolean isSynthetic()
      Determine if this Entry has been synthetically mutated. This method returns false if either a non-synthetic update was made or the entry has not been modified.
      Specified by:
      isSynthetic in interface InvocableMap.Entry<K,V>
      Returns:
      true if the Entry has been synthetically mutated

    • remove

      public void remove(boolean fSynthetic)
      Description copied from interface: InvocableMap.Entry
      Remove this Entry from the Map if it is present in the Map.

      This method supports both the operation corresponding to Map.remove(java.lang.Object) as well as synthetic operations such as eviction. If the containing Map does not differentiate between the two, then this method will always be identical to InvocableMap.this.remove(getKey()).

      Specified by:
      remove in interface InvocableMap.Entry<K,V>
      Parameters:
      fSynthetic - pass true only if the removal from the Map should be treated as a synthetic event
      Throws:
      UnsupportedOperationException - by default

    • extract

      public <T, E> E extract(ValueExtractor<T,E> extractor)
      Extract a value out of the Entry's key or value. Calling this method is semantically equivalent to extractor.extract(entry.getValue()), but this method may be significantly less expensive. For example, the resultant value may be obtained from a forward index, avoiding a potential object de-serialization.
      Specified by:
      extract in interface QueryMap.Entry<K,V>
      Type Parameters:
      T - the type of the value to extract from
      E - the type of value that will be extracted
      Parameters:
      extractor - a ValueExtractor to apply to the Entry's key or value
      Returns:
      the extracted value

    • equals

      public boolean equals(Object o)
      Compares the specified object with this entry for equality. Returns true if the given object is also a map entry and the two entries represent the same mapping. More formally, two entries e1 and e2 represent the same mapping if
           (e1.getKey()==null ?
      e2.getKey()==null : e1.getKey().equals(e2.getKey()))  &&
     (e1.getValue()==null ?
      e2.getValue()==null : e1.getValue().equals(e2.getValue()))
      This ensures that the equals method works properly across different implementations of the Map.Entry interface.
      Specified by:
      equals in interface Map.Entry<K,V>
      Overrides:
      equals in class Object
      Parameters:
      o - object to be compared for equality with this map entry
      Returns:
      true if the specified object is equal to this map entry

    • hashCode

      public int hashCode()
      Returns the hash code value for this map entry. The hash code of a map entry e is defined to be: 
           (e.getKey()==null   ? 0 : e.getKey().hashCode()) ^
     (e.getValue()==null ? 0 : e.getValue().hashCode())
      This ensures that e1.equals(e2) implies that e1.hashCode()==e2.hashCode() for any two Entries e1 and e2, as required by the general contract of Object.hashCode.
      Specified by:
      hashCode in interface Map.Entry<K,V>
      Overrides:
      hashCode in class Object
      Returns:
      the hash code value for this map entry.

    • toString

      public String toString()
      Render the map entry as a String.
      Overrides:
      toString in class Object
      Returns:
      the details about this entry

    • clone

      public Object clone()
      Clone the Entry.
      Overrides:
      clone in class Object
      Returns:
      a clone of this Entry