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org.apache.axis.collections
Class SequencedHashMap  

java.lang.Object
  org.apache.axis.collections.SequencedHashMap

All Implemented Interfaces:

java.lang.Cloneable, java.io.Externalizable, java.util.Map, java.io.Serializable

Direct Known Subclasses:

LRUMap

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public class SequencedHashMap

extends java.lang.Object

implements java.util.Map, java.lang.Cloneable, java.io.Externalizable

A map of objects whose mapping entries are sequenced based on the order in which they were added. This data structure has fast O(1) search time, deletion time, and insertion time.

Although this map is sequenced, it cannot implement java.util.List because of incompatible interface definitions. The remove methods in List and Map have different return values (see: List.remove(Object)>List.remove(Object) 55 and Map.remove(Object)>Map.remove(Object) 55 ).

This class is not thread safe. When a thread safe implementation is required, use Collections.synchronizedMap(Map)>Collections.synchronizedMap(Map) 55 as it is documented, or use explicit synchronization controls.

Since:

Commons Collections 2.0

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Nested Class Summary
private static class	SequencedHashMap.Entry           java.util.Map.Entry that doubles as a node in the linked list of sequenced mappings.
private  class	SequencedHashMap.OrderedIterator

 

Field Summary
private  java.util.HashMap	entries           Map of keys to entries
private static int	ENTRY
private static int	KEY
private  long	modCount           Holds the number of modifications that have occurred to the map, excluding modifications made through a collection view's iterator (e.g.
private static int	REMOVED_MASK
private  SequencedHashMap.Entry	sentinel           Sentinel used to hold the head and tail of the list of entries.
private static long	serialVersionUID
private static int	VALUE

 

Constructor Summary

SequencedHashMap()           Construct a new sequenced hash map with default initial size and load factor.

SequencedHashMap(int initialSize)           Construct a new sequenced hash map with the specified initial size and default load factor.

SequencedHashMap(int initialSize, float loadFactor)           Construct a new sequenced hash map with the specified initial size and load factor.

SequencedHashMap(java.util.Map m)           Construct a new sequenced hash map and add all the elements in the specified map.

 

Method Summary
void	clear()           Implements Map.clear()>Map.clear() 55 .
java.lang.Object	clone()           Creates a shallow copy of this object, preserving the internal structure by copying only references.
boolean	containsKey(java.lang.Object key)           Implements Map.containsKey(Object)>Map.containsKey(Object) 55 .
boolean	containsValue(java.lang.Object value)           Implements Map.containsValue(Object)>Map.containsValue(Object) 55 .
private static SequencedHashMap.Entry	createSentinel()           Construct an empty sentinel used to hold the head (sentinel.next) and the tail (sentinel.prev) of the list.
java.util.Set	entrySet()           Implements Map.entrySet()>Map.entrySet() 55 .
boolean	equals(java.lang.Object obj)           Implements Map.equals(Object)>Map.equals(Object) 55 .
java.lang.Object	get(int index)           Gets the key at the specified index.
java.lang.Object	get(java.lang.Object o)           Implements Map.get(Object)>Map.get(Object) 55 .
private  java.util.Map.Entry	getEntry(int index)           Returns the Map.Entry at the specified index
java.util.Map.Entry	getFirst()           Return the entry for the "oldest" mapping.
java.lang.Object	getFirstKey()           Return the key for the "oldest" mapping.
java.lang.Object	getFirstValue()           Return the value for the "oldest" mapping.
java.util.Map.Entry	getLast()           Return the entry for the "newest" mapping.
java.lang.Object	getLastKey()           Return the key for the "newest" mapping.
java.lang.Object	getLastValue()           Return the value for the "newest" mapping.
java.lang.Object	getValue(int index)           Gets the value at the specified index.
int	hashCode()           Implements Map.hashCode()>Map.hashCode() 55 .
int	indexOf(java.lang.Object key)           Gets the index of the specified key.
private  void	insertEntry(SequencedHashMap.Entry entry)           Inserts a new internal entry to the tail of the linked list.
boolean	isEmpty()           Implements Map.isEmpty()>Map.isEmpty() 55 .
java.util.Iterator	iterator()           Gets an iterator over the keys.
java.util.Set	keySet()           Implements Map.keySet()>Map.keySet() 55 .
int	lastIndexOf(java.lang.Object key)           Gets the last index of the specified key.
java.lang.Object	put(java.lang.Object key, java.lang.Object value)           Implements Map.put(Object, Object)>Map.put(Object, Object) 55 .
void	putAll(java.util.Map t)           Adds all the mappings in the specified map to this map, replacing any mappings that already exist (as per Map.putAll(Map)>Map.putAll(Map) 55 ).
void	readExternal(java.io.ObjectInput in)           Deserializes this map from the given stream.
java.lang.Object	remove(int index)           Removes the element at the specified index.
java.lang.Object	remove(java.lang.Object key)           Implements Map.remove(Object)>Map.remove(Object) 55 .
private  void	removeEntry(SequencedHashMap.Entry entry)           Removes an internal entry from the linked list.
private  SequencedHashMap.Entry	removeImpl(java.lang.Object key)           Fully remove an entry from the map, returning the old entry or null if there was no such entry with the specified key.
java.util.List	sequence()           Returns a List view of the keys rather than a set view.
int	size()           Implements Map.size()>Map.size() 55 .
java.lang.String	toString()           Provides a string representation of the entries within the map.
java.util.Collection	values()           Implements Map.values()>Map.values() 55 .
void	writeExternal(java.io.ObjectOutput out)           Serializes this map to the given stream.

 

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

 

Field Detail

sentinel

private SequencedHashMap.Entry sentinel

Sentinel used to hold the head and tail of the list of entries.

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entries

private java.util.HashMap entries

Map of keys to entries

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modCount

private transient long modCount

Holds the number of modifications that have occurred to the map, excluding modifications made through a collection view's iterator (e.g. entrySet().iterator().remove()). This is used to create a fail-fast behavior with the iterators.

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KEY

private static final int KEY

See Also:

Constant Field Values

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VALUE

private static final int VALUE

See Also:

Constant Field Values

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ENTRY

private static final int ENTRY

See Also:

Constant Field Values

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REMOVED_MASK

private static final int REMOVED_MASK

See Also:

Constant Field Values

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serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

Constructor Detail

SequencedHashMap

public SequencedHashMap()

Construct a new sequenced hash map with default initial size and load factor.

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SequencedHashMap

public SequencedHashMap(int initialSize)

Construct a new sequenced hash map with the specified initial size and default load factor.

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SequencedHashMap

public SequencedHashMap(int initialSize,
                        float loadFactor)

Construct a new sequenced hash map with the specified initial size and load factor.

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SequencedHashMap

public SequencedHashMap(java.util.Map m)

Construct a new sequenced hash map and add all the elements in the specified map. The order in which the mappings in the specified map are added is defined by putAll(Map) 55 .

Method Detail

createSentinel

private static final SequencedHashMap.Entry createSentinel()

Construct an empty sentinel used to hold the head (sentinel.next) and the tail (sentinel.prev) of the list. The sentinal has a null key and value.

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removeEntry

private void removeEntry(SequencedHashMap.Entry entry)

Removes an internal entry from the linked list. This does not remove it from the underlying map.

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insertEntry

private void insertEntry(SequencedHashMap.Entry entry)

Inserts a new internal entry to the tail of the linked list. This does not add the entry to the underlying map.

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size

public int size()

Implements Map.size()>Map.size() 55 .

Specified by:

size in interface java.util.Map

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isEmpty

public boolean isEmpty()

Implements Map.isEmpty()>Map.isEmpty() 55 .

Specified by:

isEmpty in interface java.util.Map

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containsKey

public boolean containsKey(java.lang.Object key)

Implements Map.containsKey(Object)>Map.containsKey(Object) 55 .

Specified by:

containsKey in interface java.util.Map

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containsValue

public boolean containsValue(java.lang.Object value)

Implements Map.containsValue(Object)>Map.containsValue(Object) 55 .

Specified by:

containsValue in interface java.util.Map

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get

public java.lang.Object get(java.lang.Object o)

Implements Map.get(Object)>Map.get(Object) 55 .

Specified by:

get in interface java.util.Map

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getFirst

public java.util.Map.Entry getFirst()

Return the entry for the "oldest" mapping. That is, return the Map.Entry for the key-value pair that was first put into the map when compared to all the other pairings in the map. This behavior is equivalent to using entrySet().iterator().next(), but this method provides an optimized implementation.

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getFirstKey

public java.lang.Object getFirstKey()

Return the key for the "oldest" mapping. That is, return the key for the mapping that was first put into the map when compared to all the other objects in the map. This behavior is equivalent to using getFirst().getKey(), but this method provides a slightly optimized implementation.

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getFirstValue

public java.lang.Object getFirstValue()

Return the value for the "oldest" mapping. That is, return the value for the mapping that was first put into the map when compared to all the other objects in the map. This behavior is equivalent to using getFirst().getValue(), but this method provides a slightly optimized implementation.

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getLast

public java.util.Map.Entry getLast()

Return the entry for the "newest" mapping. That is, return the Map.Entry for the key-value pair that was first put into the map when compared to all the other pairings in the map. The behavior is equivalent to:

    Object obj = null;
    Iterator iter = entrySet().iterator();
    while(iter.hasNext()) {
      obj = iter.next();
    }
    return (Map.Entry)obj;
  

However, the implementation of this method ensures an O(1) lookup of the last key rather than O(n).

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getLastKey

public java.lang.Object getLastKey()

Return the key for the "newest" mapping. That is, return the key for the mapping that was last put into the map when compared to all the other objects in the map. This behavior is equivalent to using getLast().getKey(), but this method provides a slightly optimized implementation.

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getLastValue

public java.lang.Object getLastValue()

Return the value for the "newest" mapping. That is, return the value for the mapping that was last put into the map when compared to all the other objects in the map. This behavior is equivalent to using getLast().getValue(), but this method provides a slightly optimized implementation.

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put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Implements Map.put(Object, Object)>Map.put(Object, Object) 55 .

Specified by:

put in interface java.util.Map

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remove

public java.lang.Object remove(java.lang.Object key)

Implements Map.remove(Object)>Map.remove(Object) 55 .

Specified by:

remove in interface java.util.Map

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removeImpl

private SequencedHashMap.Entry removeImpl(java.lang.Object key)

Fully remove an entry from the map, returning the old entry or null if there was no such entry with the specified key.

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putAll

public void putAll(java.util.Map t)

Adds all the mappings in the specified map to this map, replacing any mappings that already exist (as per Map.putAll(Map)>Map.putAll(Map) 55 ). The order in which the entries are added is determined by the iterator returned from Map.entrySet()>Map.entrySet() 55 for the specified map.

Specified by:

putAll in interface java.util.Map

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clear

public void clear()

Implements Map.clear()>Map.clear() 55 .

Specified by:

clear in interface java.util.Map

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equals

public boolean equals(java.lang.Object obj)

Implements Map.equals(Object)>Map.equals(Object) 55 .

Specified by:

equals in interface java.util.Map

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hashCode

public int hashCode()

Implements Map.hashCode()>Map.hashCode() 55 .

Specified by:

hashCode in interface java.util.Map

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toString

public java.lang.String toString()

Provides a string representation of the entries within the map. The format of the returned string may change with different releases, so this method is suitable for debugging purposes only. If a specific format is required, use entrySet() 55 .iterator() 55 and iterate over the entries in the map formatting them as appropriate.

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keySet

public java.util.Set keySet()

Implements Map.keySet()>Map.keySet() 55 .

Specified by:

keySet in interface java.util.Map

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values

public java.util.Collection values()

Implements Map.values()>Map.values() 55 .

Specified by:

values in interface java.util.Map

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entrySet

public java.util.Set entrySet()

Implements Map.entrySet()>Map.entrySet() 55 .

Specified by:

entrySet in interface java.util.Map

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clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Creates a shallow copy of this object, preserving the internal structure by copying only references. The keys and values themselves are not clone()'d. The cloned object maintains the same sequence.

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getEntry

private java.util.Map.Entry getEntry(int index)

Returns the Map.Entry at the specified index

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get

public java.lang.Object get(int index)

Gets the key at the specified index.

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getValue

public java.lang.Object getValue(int index)

Gets the value at the specified index.

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indexOf

public int indexOf(java.lang.Object key)

Gets the index of the specified key.

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iterator

public java.util.Iterator iterator()

Gets an iterator over the keys.

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lastIndexOf

public int lastIndexOf(java.lang.Object key)

Gets the last index of the specified key.

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sequence

public java.util.List sequence()

Returns a List view of the keys rather than a set view. The returned list is unmodifiable. This is required because changes to the values of the list (using ListIterator.set(Object)>ListIterator.set(Object) 55 ) will effectively remove the value from the list and reinsert that value at the end of the list, which is an unexpected side effect of changing the value of a list. This occurs because changing the key, changes when the mapping is added to the map and thus where it appears in the list.

An alternative to this method is to use keySet() 55

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remove

public java.lang.Object remove(int index)

Removes the element at the specified index.

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readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Deserializes this map from the given stream.

Specified by:

readExternal in interface java.io.Externalizable

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writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Serializes this map to the given stream.

Specified by:

writeExternal in interface java.io.Externalizable

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> org >> apache >> axis >> [ collections overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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