com.tangosol.util.AbstractKeyBasedMap Maven / Gradle / Ivy
Show all versions of coherence Show documentation
/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.util;
import com.tangosol.net.cache.CacheEvent;
import java.util.AbstractCollection;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* AbstractKeyBasedMap is a base class for Map implementations. The primary
* difference between the {@link java.util.AbstractMap} abstract class and
* this abstract class is this: that AbstractMap requires a sub-class to
* provide an Entry Set implementation, while AbstractKeyBasedMap requires a
* read-only sub-class to implement only get() and iterateKeys(), and a
* read-write sub-class to additionally implement only put() and remove().
*
* Read-only implementations must implement {@link #iterateKeys()} and
* {@link #get(Object)}. Read/write implementations must additionally
* implement {@link #put(Object, Object)} and {@link #remove(Object)}. A
* number of the methods have implementations provided, but are extremely
* inefficient for Maps that contain large amounts of data, including
* {@link #clear()}, {@link #containsKey(Object)}, {@link #size()} (and by
* extension {@link #isEmpty()}). Furthermore, if any of a number of method
* implementations has any cost of returning an "old value", such as is done
* by the {@link #put} and {@link #remove(Object)} methods, then the
* {@link #putAll(java.util.Map)} and {@link #removeBlind(Object)}
* methods should also be implemented.
*
* @author 2005.07.13 cp
*/
public abstract class AbstractKeyBasedMap
extends Base
implements Map
{
// ----- Map interface --------------------------------------------------
/**
* Clear all key/value mappings.
*/
public void clear()
{
// this begs for sub-class optimization
for (Iterator iter = iterateKeys(); iter.hasNext(); )
{
iter.next();
iter.remove();
}
}
/**
* Returns true if this map contains a mapping for the specified
* key.
*
* @return true if this map contains a mapping for the specified
* key, false otherwise.
*/
public boolean containsKey(Object oKey)
{
// this begs for sub-class optimization
for (Iterator iter = iterateKeys(); iter.hasNext(); )
{
if (equals(oKey, iter.next()))
{
return true;
}
}
return false;
}
/**
* Returns true if this Map maps one or more keys to the
* specified value.
*
* @return true if this Map maps one or more keys to the
* specified value, false otherwise
*/
public boolean containsValue(Object oValue)
{
return values().contains(oValue);
}
/**
* Returns a set view of the mappings contained in this map. Each element
* in the returned set is an {@link Entry}. The set is backed by the
* map, so changes to the map are reflected in the set, and vice-versa.
* If the map is modified while an iteration over the set is in progress
* (except by the iterator's own remove operation, or by the
* setValue operation on a map entry returned by the iterator)
* the results of the iteration are undefined. The set supports element
* removal, which removes the corresponding mapping from the map, via the
* Iterator.remove, Set.remove, removeAll,
* retainAll and clear operations. It is not expected to
* support the add or addAll operations.
*
* @return a set view of the mappings contained in this map
*/
public Set> entrySet()
{
// no need to synchronize; it is acceptable that two threads would
// instantiate an entry set
Set> set = m_setEntries;
if (set == null)
{
m_setEntries = set = instantiateEntrySet();
}
return set;
}
/**
* Returns the value to which this map maps the specified key.
*
* @param oKey the key object
*
* @return the value to which this map maps the specified key,
* or null if the map contains no mapping for this key
*/
public abstract V get(Object oKey);
/**
* Returns true if this map contains no key-value mappings.
*
* @return true if this map contains no key-value mappings
*/
public boolean isEmpty()
{
return size() == 0;
}
/**
* Returns a set view of the keys contained in this map. The set is
* backed by the map, so changes to the map are reflected in the set, and
* vice-versa. If the map is modified while an iteration over the set is
* in progress (except through the iterator's own remove
* operation), the results of the iteration are undefined. The set
* supports element removal, which removes the corresponding mapping from
* the map, via the Iterator.remove, Set.remove,
* removeAll retainAll, and clear operations.
* It is not expected to support the add or addAll operations.
*
* @return a set view of the keys contained in this map
*/
public Set keySet()
{
// no need to synchronize; it is acceptable that two threads would
// instantiate a key set
Set set = m_setKeys;
if (set == null)
{
m_setKeys = set = instantiateKeySet();
}
return set;
}
/**
* Associates the specified value with the specified key in this map.
*
* @param oKey key with which the specified value is to be associated
* @param oValue value to be associated with the specified key
*
* @return previous value associated with specified key, or null
* if there was no mapping for key
*/
public V put(K oKey, V oValue)
{
throw new UnsupportedOperationException();
}
/**
* Copies all of the mappings from the specified map to this map. The
* effect of this call is equivalent to that of calling {@link #put}
* on this map once for each mapping in the passed map. The behavior of
* this operation is unspecified if the passed map is modified while the
* operation is in progress.
*
* @param map the Map containing the key/value pairings to put into this
* Map
*/
public void putAll(Map map)
{
for (Map.Entry entry : map.entrySet())
{
put(entry.getKey(), entry.getValue());
}
}
/**
* Removes the mapping for this key from this map if present.
* Expensive: updates both the underlying cache and the local cache.
*
* @param oKey key whose mapping is to be removed from the map
*
* @return previous value associated with specified key, or null
* if there was no mapping for key. A null return can
* also indicate that the map previously associated null
* with the specified key, if the implementation supports
* null values.
*/
public V remove(Object oKey)
{
throw new UnsupportedOperationException();
}
/**
* Returns the number of key-value mappings in this map.
*
* @return the number of key-value mappings in this map
*/
public int size()
{
// this begs for sub-class optimization
int c = 0;
for (Iterator iter = iterateKeys(); iter.hasNext(); )
{
iter.next();
++c;
}
return c;
}
/**
* Returns a collection view of the values contained in this map. The
* collection is backed by the map, so changes to the map are reflected in
* the collection, and vice-versa. If the map is modified while an
* iteration over the collection is in progress (except through the
* iterator's own remove operation), the results of the
* iteration are undefined. The collection supports element removal,
* which removes the corresponding mapping from the map, via the
* Iterator.remove, Collection.remove,
* removeAll, retainAll and clear operations.
* It is not expected to support the add or addAll operations.
*
* @return a Collection view of the values contained in this map
*/
public Collection values()
{
// no need to synchronize; it is acceptable that two threads would
// instantiate a key set
Collection coll = m_collValues;
if (coll == null)
{
m_collValues = coll = instantiateValues();
}
return coll;
}
// ----- CacheMap methods -----------------------------------------------
/**
* Get all the specified keys, if they are in the Map. For each key
* that is in the cache, that key and its corresponding value will be
* placed in the map that is returned by this method. The absence of
* a key in the returned map indicates that it was not in the cache,
* which may imply (for caches that can load behind the scenes) that
* the requested data could not be loaded.
*
* @param colKeys a collection of keys that may be in the named cache
*
* @return a Map of keys to values for the specified keys passed in
* colKeys
*/
public Map getAll(Collection colKeys)
{
Map map = new ListMap<>();
for (K key : colKeys)
{
V val = get(key);
if (val != null || containsKey(key))
{
map.put(key, val);
}
}
return map;
}
// ----- internal methods -----------------------------------------------
/**
* Create an iterator over the keys in this Map. The Iterator must
* support remove() if the Map supports removal.
*
* @return a new instance of an Iterator over the keys in this Map
*/
protected abstract Iterator iterateKeys();
/**
* Removes the mapping for this key from this map if present. This method
* exists to allow sub-classes to optimize remove functionality for
* situations in which the original value is not required.
*
* @param oKey key whose mapping is to be removed from the map
*
* @return true iff the Map changed as the result of this operation
*/
protected boolean removeBlind(Object oKey)
{
if (containsKey(oKey))
{
remove(oKey);
return true;
}
else
{
return false;
}
}
// ----- Object methods -------------------------------------------------
/**
* Compares the specified object with this map for equality. Returns
* true if the given object is also a map and the two maps
* represent the same mappings. More formally, two maps t1 and
* t2 represent the same mappings if
* t1.keySet().equals(t2.keySet()) and for every key k
* in t1.keySet(), (t1.get(k)==null ? t2.get(k)==null :
* t1.get(k).equals(t2.get(k))) . This ensures that the
* equals method works properly across different implementations
* of the map interface.
*
* @param o object to be compared for equality with this Map
*
* @return true if the specified object is equal to this Map
*/
public boolean equals(Object o)
{
if (o instanceof Map)
{
Map that = (Map) o;
if (this == that)
{
return true;
}
if (this.size() == that.size())
{
for (Entry entry : entrySet())
{
Object oKey = entry.getKey();
Object oThisValue = entry.getValue();
Object oThatValue;
try
{
oThatValue = that.get(oKey);
}
catch (ClassCastException e)
{
// to be compatible with java.util.AbstractMap
return false;
}
catch (NullPointerException e)
{
// to be compatible with java.util.AbstractMap
return false;
}
if (oThisValue == this || oThisValue == that)
{
// this could be infinite recursion
if (oThatValue != this && oThatValue != that)
{
// it is not safe to call equals(); it would
// likely lead to infinite recursion
return false;
}
}
else if (!equals(oThisValue, oThatValue)
|| oThatValue == null && !that.containsKey(oKey))
{
return false;
}
}
// size is identical and all entries match
return true;
}
}
return false;
}
/**
* Returns the hash code value for this Map. The hash code of a Map is
* defined to be the sum of the hash codes of each entry in the Map's
* entrySet() view. This ensures that t1.equals(t2)
* implies that t1.hashCode()==t2.hashCode() for any two maps
* t1 and t2, as required by the general contract of
* Object.hashCode.
*
* @return the hash code value for this Map
*/
public int hashCode()
{
int nHash = 0;
for (Entry entry : entrySet())
{
nHash += entry.hashCode();
}
return nHash;
}
/**
* Returns a string representation of this Map. The string representation
* consists of a list of key-value mappings in the order returned by the
* Map's entrySet view's iterator, enclosed in braces
* ("{}"). Adjacent mappings are separated by the characters
* ", " (comma and space). Each key-value mapping is rendered as
* the key followed by an equals sign ("=") followed by the
* associated value. Keys and values are converted to strings as by
* String.valueOf(Object).
*
* @return a String representation of this Map
*/
public String toString()
{
StringBuilder sb = new StringBuilder(100 + (size() << 3));
sb.append('{');
boolean fFirst = true;
for (Entry entry : entrySet())
{
if (fFirst)
{
fFirst = false;
}
else
{
sb.append(", ");
}
K key = entry.getKey();
V value = entry.getValue();
// as per AbstractMap, detect the condition in which case this
// map is used as a key and/or a value inside itself, which
// would result in infinite recursion
sb.append(key == this ? "(this Map)" : String.valueOf(key))
.append('=')
.append(value == this ? "(this Map)" : String.valueOf(value));
}
sb.append('}');
return sb.toString();
}
/**
* Returns a shallow copy of this AbstractKeyBasedMap instance;
* the keySet, entrySet and values collections are not cloned or copied
* to (shared by) the clone.
*
* @return a shallow copy of this map
*/
protected Object clone()
throws CloneNotSupportedException
{
AbstractKeyBasedMap that = (AbstractKeyBasedMap) super.clone();
that.m_setKeys = null;
that.m_setEntries = null;
that.m_collValues = null;
return that;
}
// ----- inner class: DeferredCacheEvent --------------------------------
/**
* A DeferredCacheEvent is a {@link CacheEvent} object that defers the loading
* of the {@link #getOldValue() old value}.
*
* This event has two predominant states; active and inactive. The event is
* active from incarnation and can transition to inactive (via {@link #deactivate()})
* but not vice-versa. Being active allows the getOldValue implementation
* to load the value from underlying map, thus all consumers of this
* event must ensure they call getOldValue prior to returning control when
* this event is dispatched.
*
* Once inactive the correct value may no longer be available in the map
* thus in this state a getOldValue will return either null or the cached old value.
*/
protected abstract static class DeferredCacheEvent
extends CacheEvent
{
// ----- constructors -----------------------------------------------
/**
* Constructs a new DeferredCacheEvent.
*
* @param map the ObservableMap
* @param nId this event's id, one of {@link #ENTRY_INSERTED},
* {@link #ENTRY_UPDATED} or {@link #ENTRY_DELETED}
* @param oKey the key into the map
* @param oValueOld the old value (for update and delete events)
* @param oValueNew the new value (for insert and update events)
* @param fSynthetic true iff the event is caused by the cache
* internal processing such as eviction or loading
*/
public DeferredCacheEvent(ObservableMap map, int nId, K oKey,
V oValueOld, V oValueNew, boolean fSynthetic)
{
super(map, nId, oKey,
oValueOld == null ? (V) NO_VALUE : oValueOld, oValueNew, fSynthetic);
}
// ----- helper methods ---------------------------------------------
/**
* {@inheritDoc}
*/
@Override
public V getOldValue()
{
// since m_oValueOld is not volatile we double read the volatile
// m_fActive to ensure the event was not deactivated whilst we were
// loading the old value
V oValueOld = m_oValueOld;
if (oValueOld == NO_VALUE && m_fActive)
{
oValueOld = readOldValue();
if (m_fActive)
{
return m_oValueOld = oValueOld;
}
}
return oValueOld == NO_VALUE ? null : oValueOld;
}
/**
* Perform a deferred read for the old value in a usage-specific way.
*
* @return the old value
*/
protected abstract V readOldValue();
/**
* Deactivate this DeferredCacheEvent instance. This is used to prevent
* future {@link #getOldValue()} calls using the underlying map *after*
* the event dispatching code returned and the content of the map had
* been changed to a new value.
*
* The contract between the DeferredCacheEvent and consumers of
* the event states that consumers must call {@code getOldValue} prior to
* returning from event dispatching logic.
*/
public void deactivate()
{
if (m_oValueOld == NO_VALUE)
{
m_oValueOld = null;
}
m_fActive = false;
}
/**
* Whether the DeferredCacheEvent is in an active or inactive state.
*/
protected volatile boolean m_fActive = true;
}
// ----- inner class: KeySet --------------------------------------------
/**
* Factory pattern: Create a Set that represents the keys in the Map
*
* @return a new instance of Set that represents the keys in the Map
*/
protected Set instantiateKeySet()
{
return new KeySet();
}
/**
* A set of keys backed by this map.
*/
protected class KeySet
extends AbstractSet
{
// ----- Set interface ------------------------------------------
/**
* Removes all of the elements from this set of Keys by clearing the
* underlying Map.
*/
public void clear()
{
AbstractKeyBasedMap.this.clear();
}
/**
* Returns true if this collection contains the specified
* element. More formally, returns true if and only if this
* collection contains at least one element e such that
* (o==null ? e==null : o.equals(e)).
*
* @param o object to be checked for containment in this collection
*
* @return true if this collection contains the specified
* element
*/
public boolean contains(Object o)
{
return AbstractKeyBasedMap.this.containsKey(o);
}
/**
* Returns true if this Set is empty.
*
* @return true if this Set is empty
*/
public boolean isEmpty()
{
return AbstractKeyBasedMap.this.isEmpty();
}
/**
* Returns an iterator over the elements contained in this collection.
*
* @return an iterator over the elements contained in this collection
*/
public Iterator iterator()
{
if (isEmpty())
{
return NullImplementation.getIterator();
}
return AbstractKeyBasedMap.this.iterateKeys();
}
/**
* Removes the specified element from this Set of keys if it is
* present by removing the associated key from the underlying
* Map.
*
* @param o object to be removed from this set, if present
*
* @return true if the set contained the specified element
*/
public boolean remove(Object o)
{
return AbstractKeyBasedMap.this.removeBlind(o);
}
/**
* Returns the number of elements in this collection.
*
* @return the number of elements in this collection
*/
public int size()
{
return AbstractKeyBasedMap.this.size();
}
}
// ----- inner class: EntrySet ------------------------------------------
/**
* Factory pattern: Create a Set that represents the entries in the Map.
*
* @return a new instance of Set that represents the entries in the Map
*/
protected Set> instantiateEntrySet()
{
return new EntrySet();
}
/**
* A set of entries backed by this map.
*/
public class EntrySet
extends AbstractSet>
{
// ----- Set interface ------------------------------------------
/**
* Removes all of the elements from this set of Keys by clearing the
* underlying Map.
*/
public void clear()
{
AbstractKeyBasedMap.this.clear();
}
/**
* Returns true if this collection contains the specified
* element. More formally, returns true if and only if this
* collection contains at least one element e such that
* (o==null ? e==null : o.equals(e)).
*
* @param o object to be checked for containment in this collection
*
* @return true if this collection contains the specified
* element
*/
public boolean contains(Object o)
{
if (o instanceof Map.Entry)
{
Map.Entry entry = (Map.Entry) o;
Object oKey = entry.getKey();
Object oValue = entry.getValue();
Map map = AbstractKeyBasedMap.this;
return Base.equals(oValue, map.get(oKey))
&& (oValue != null || map.containsKey(oKey));
}
return false;
}
/**
* Returns true if this Set is empty.
*
* @return true if this Set is empty
*/
public boolean isEmpty()
{
return AbstractKeyBasedMap.this.isEmpty();
}
/**
* Returns an iterator over the elements contained in this collection.
*
* @return an iterator over the elements contained in this collection
*/
public Iterator> iterator()
{
if (isEmpty())
{
return NullImplementation.getIterator();
}
return instantiateIterator();
}
/**
* Removes the specified element from this Set of entries if it is
* present by removing the associated entry from the underlying Map.
*
* @param o object to be removed from this set, if present
*
* @return true if the set contained the specified element
*/
public boolean remove(Object o)
{
if (contains(o))
{
AbstractKeyBasedMap.this.remove(((Map.Entry) o).getKey());
return true;
}
else
{
return false;
}
}
/**
* Returns the number of elements in this collection.
*
* @return the number of elements in this collection
*/
public int size()
{
return AbstractKeyBasedMap.this.size();
}
// ----- inner class: Entry -------------------------------------
/**
* Factory pattern. Create a Map Entry.
*
* @param oKey the Entry key (required)
* @param oValue the Entry value (optional; lazy loaded if necessary)
*
* @return a new instance of an Entry with the specified key and
* value (if one is provided)
*/
protected Map.Entry instantiateEntry(K oKey, V oValue)
{
return new Entry(oKey, oValue);
}
/**
* A Map Entry implementation that defers its value acquisition from
* the containing map (via {@link Map#get(Object)}) if the Entry is
* constructed with a null value.
*/
protected class Entry
extends SimpleMapEntry
{
/**
* Construct an Entry.
*
* @param oKey the Entry key
* @param oValue the Entry value (optional)
*/
public Entry(K oKey, V oValue)
{
super(oKey, oValue);
}
/**
* Returns the value corresponding to this entry.
*
* @return the value corresponding to this entry
*/
public V getValue()
{
V oValue = super.getValue();
if (oValue == null)
{
oValue = AbstractKeyBasedMap.this.get(getKey());
super.setValue(oValue);
}
return oValue;
}
/**
* Replaces the value corresponding to this entry with the
* specified value (optional operation). (Writes through
* to the map.)
*
* @param oValue new value to be stored in this entry
*
* @return old value corresponding to the entry
*/
public V setValue(V oValue)
{
V oValueOrig = AbstractKeyBasedMap.this.put(getKey(), oValue);
super.setValue(oValue);
return oValueOrig;
}
/**
* 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.
*
* @return the hash code value for this map entry.
*/
public int hashCode()
{
K oKey = getKey();
V oValue = getValue();
AbstractKeyBasedMap map = AbstractKeyBasedMap.this;
return (oKey == null || oKey == map ? 0 : oKey .hashCode()) ^
(oValue == null || oValue == map ? 0 : oValue.hashCode());
}
}
// ----- inner class: Entry Set Iterator ------------------------
/**
* Factory pattern.
*
* @return a new instance of an Iterator over the EntrySet
*/
protected Iterator> instantiateIterator()
{
return new EntrySetIterator();
}
/**
* An Iterator over the EntrySet that is backed by the Map.
*/
protected class EntrySetIterator
implements Iterator>
{
// ----- Iterator interface -----------------------------
/**
* Returns true if the iteration has more elements. (In
* other words, returns true if next would
* return an element rather than throwing an exception.)
*
* @return true if the iterator has more elements
*/
public boolean hasNext()
{
return m_iterKeys.hasNext();
}
/**
* Returns the next element in the iteration.
*
* @return the next element in the iteration
*
* @exception NoSuchElementException iteration has no more elements
*/
public Map.Entry next()
{
return instantiateEntry(m_iterKeys.next(), /*value*/ null);
}
/**
* Removes from the underlying collection the last element
* returned by the iterator. This method can be called only once
* per call to next. The behavior of an iterator is
* unspecified if the underlying collection is modified while the
* iteration is in progress in any way other than by calling this
* method.
*
* @exception IllegalStateException if the next method
* has not yet been called, or the remove
* method has already been called after the last call
* to the next method
*/
public void remove()
{
m_iterKeys.remove();
}
// ----- data members -----------------------------------
/**
* Key iterator.
*/
protected Iterator m_iterKeys = AbstractKeyBasedMap.this.iterateKeys();
}
}
// ----- inner class: ValuesCollection ----------------------------------
/**
* Factory pattern: Instantiate the values Collection.
*
* @return a new instance of Collection that represents this Map's values
*/
protected Collection instantiateValues()
{
return new ValuesCollection();
}
/**
* A Collection of values backed by this map.
*/
protected class ValuesCollection
extends AbstractCollection
{
// ----- Set interface ------------------------------------------
/**
* Removes all of the elements from this Collection by clearing the
* underlying Map.
*/
public void clear()
{
AbstractKeyBasedMap.this.clear();
}
/**
* Returns true if this collection contains the specified
* element. More formally, returns true if and only if this
* collection contains at least one element e such that
* (o==null ? e==null : o.equals(e)).
*
* @param o object to be checked for containment in this collection
*
* @return true if this collection contains the specified
* element
*/
public boolean contains(Object o)
{
// this is hardly optimal, and sub-classes that have better
// means to implement this should do so
if (o == null)
{
for (Iterator iter = iterator(); iter.hasNext(); )
{
if (iter.next() == null)
{
return true;
}
}
}
else
{
for (Iterator iter = iterator(); iter.hasNext(); )
{
if (Base.equals(o, iter.next()))
{
return true;
}
}
}
return false;
}
/**
* Returns true if this Set is empty.
*
* @return true if this Set is empty
*/
public boolean isEmpty()
{
return AbstractKeyBasedMap.this.isEmpty();
}
/**
* Returns an iterator over the elements contained in this collection.
*
* @return an iterator over the elements contained in this collection
*/
public Iterator iterator()
{
if (isEmpty())
{
return NullImplementation.getIterator();
}
return instantiateIterator();
}
/**
* Removes the specified element from this Collection of values if it
* is present by removing the associated key/value mapping from the
* underlying Map.
*
* @param o object to be removed from this Collection, if present
*
* @return true if the Collection contained the specified element
*/
public boolean remove(Object o)
{
// this is hardly optimal, and sub-classes that have better
// means to implement this should do so
if (o == null)
{
for (Iterator iter = iterator(); iter.hasNext(); )
{
if (iter.next() == null)
{
iter.remove();
return true;
}
}
}
else
{
for (Iterator iter = iterator(); iter.hasNext(); )
{
if (Base.equals(o, iter.next()))
{
iter.remove();
return true;
}
}
}
return false;
}
/**
* Returns the number of elements in this collection.
*
* @return the number of elements in this collection
*/
public int size()
{
return AbstractKeyBasedMap.this.size();
}
// ----- inner class: Values Collection Iterator ----------------
/**
* Factory pattern: Create a values Iterator.
*
* @return a new instance of an Iterator over the values Collection
*/
protected Iterator instantiateIterator()
{
return new ValuesIterator();
}
/**
* An Iterator over the values Collection that is backed by the
* AbstractKeyBasedMap.
*/
protected class ValuesIterator
implements Iterator
{
// ----- Iterator interface -----------------------------
/**
* Returns true if the iteration has more elements. (In
* other words, returns true if next would
* return an element rather than throwing an exception.)
*
* @return true if the iterator has more elements
*/
public boolean hasNext()
{
return m_iterKeys.hasNext();
}
/**
* Returns the next element in the iteration.
*
* @return the next element in the iteration
*
* @exception NoSuchElementException iteration has no more elements
*/
public V next()
{
return AbstractKeyBasedMap.this.get(m_iterKeys.next());
}
/**
* Removes from the underlying collection the last element
* returned by the iterator. This method can be called only once
* per call to next. The behavior of an iterator is
* unspecified if the underlying collection is modified while the
* iteration is in progress in any way other than by calling this
* method.
*
* @exception IllegalStateException if the next method
* has not yet been called, or the remove
* method has already been called after the last call
* to the next method
*/
public void remove()
{
m_iterKeys.remove();
}
// ----- data members -----------------------------------
/**
* A key iterator.
*/
protected Iterator m_iterKeys = AbstractKeyBasedMap.this.iterateKeys();
}
}
// ----- data fields ----------------------------------------------------
/**
* The key Set for this Map; lazily instantiated.
*/
private transient Set m_setKeys;
/**
* The entry Set for this Map; lazily instantiated.
*/
private transient Set> m_setEntries;
/**
* The values Collection for this Map; lazily instantiated.
*/
private transient Collection m_collValues;
/**
* Constant to indicate the old value in a DeferredCacheEvent has not been
* populated.
*/
private static final Object NO_VALUE = new Object();
}