Class DoubleOrderedMap

java.lang.Object
java.util.AbstractMap
org.apache.commons.collections.DoubleOrderedMap
All Implemented Interfaces:
Map

public final class DoubleOrderedMap extends AbstractMap
Deprecated.
Replaced by TreeBidiMap in bidimap subpackage. Due to be removed in v4.0.
Red-Black tree-based implementation of Map. This class guarantees that the map will be in both ascending key order and ascending value order, sorted according to the natural order for the key's and value's classes.

This Map is intended for applications that need to be able to look up a key-value pairing by either key or value, and need to do so with equal efficiency.

While that goal could be accomplished by taking a pair of TreeMaps and redirecting requests to the appropriate TreeMap (e.g., containsKey would be directed to the TreeMap that maps values to keys, containsValue would be directed to the TreeMap that maps keys to values), there are problems with that implementation, particularly when trying to keep the two TreeMaps synchronized with each other. And if the data contained in the TreeMaps is large, the cost of redundant storage becomes significant. (See also the new DualTreeBidiMap and DualHashBidiMap implementations.)

This solution keeps the data properly synchronized and minimizes the data storage. The red-black algorithm is based on TreeMap's, but has been modified to simultaneously map a tree node by key and by value. This doubles the cost of put operations (but so does using two TreeMaps), and nearly doubles the cost of remove operations (there is a savings in that the lookup of the node to be removed only has to be performed once). And since only one node contains the key and value, storage is significantly less than that required by two TreeMaps.

There are some limitations placed on data kept in this Map. The biggest one is this:

When performing a put operation, neither the key nor the value may already exist in the Map. In the java.util Map implementations (HashMap, TreeMap), you can perform a put with an already mapped key, and neither cares about duplicate values at all ... but this implementation's put method with throw an IllegalArgumentException if either the key or the value is already in the Map.

Obviously, that same restriction (and consequence of failing to heed that restriction) applies to the putAll method.

The Map.Entry instances returned by the appropriate methods will not allow setValue() and will throw an UnsupportedOperationException on attempts to call that method.

New methods are added to take advantage of the fact that values are kept sorted independently of their keys:

Object getKeyForValue(Object value) is the opposite of get; it takes a value and returns its key, if any.

Object removeValue(Object value) finds and removes the specified value and returns the now un-used key.

Set entrySetByValue() returns the Map.Entry's in a Set whose iterator will iterate over the Map.Entry's in ascending order by their corresponding values.

Set keySetByValue() returns the keys in a Set whose iterator will iterate over the keys in ascending order by their corresponding values.

Collection valuesByValue() returns the values in a Collection whose iterator will iterate over the values in ascending order.

Since:
Commons Collections 2.0
Version:
$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
See Also:
  • Field Details

    • KEY

      private static final int KEY
      Deprecated.
      See Also:
    • VALUE

      private static final int VALUE
      Deprecated.
      See Also:
    • SUM_OF_INDICES

      private static final int SUM_OF_INDICES
      Deprecated.
      See Also:
    • FIRST_INDEX

      private static final int FIRST_INDEX
      Deprecated.
      See Also:
    • NUMBER_OF_INDICES

      private static final int NUMBER_OF_INDICES
      Deprecated.
      See Also:
    • dataName

      private static final String[] dataName
      Deprecated.
    • rootNode

      private DoubleOrderedMap.Node[] rootNode
      Deprecated.
    • nodeCount

      private int nodeCount
      Deprecated.
    • modifications

      private int modifications
      Deprecated.
    • setOfKeys

      private Set[] setOfKeys
      Deprecated.
    • setOfEntries

      private Set[] setOfEntries
      Deprecated.
    • collectionOfValues

      private Collection[] collectionOfValues
      Deprecated.
  • Constructor Details

    • DoubleOrderedMap

      public DoubleOrderedMap()
      Deprecated.
      Construct a new DoubleOrderedMap
    • DoubleOrderedMap

      Deprecated.
      Constructs a new DoubleOrderedMap from an existing Map, with keys and values sorted
      Parameters:
      map - the map whose mappings are to be placed in this map.
      Throws:
      ClassCastException - if the keys in the map are not Comparable, or are not mutually comparable; also if the values in the map are not Comparable, or are not mutually Comparable
      NullPointerException - if any key or value in the map is null
      IllegalArgumentException - if there are duplicate keys or duplicate values in the map
  • Method Details

    • getKeyForValue

      public Object getKeyForValue(Object value) throws ClassCastException, NullPointerException
      Deprecated.
      Returns the key to which this map maps the specified value. Returns null if the map contains no mapping for this value.
      Parameters:
      value - value whose associated key is to be returned.
      Returns:
      the key to which this map maps the specified value, or null if the map contains no mapping for this value.
      Throws:
      ClassCastException - if the value is of an inappropriate type for this map.
      NullPointerException - if the value is null
    • removeValue

      public Object removeValue(Object value)
      Deprecated.
      Removes the mapping for this value from this map if present
      Parameters:
      value - value whose mapping is to be removed from the map.
      Returns:
      previous key associated with specified value, or null if there was no mapping for value.
    • entrySetByValue

      public Set entrySetByValue()
      Deprecated.
      Returns a set view of the mappings contained in this map. Each element in the returned set is a Map.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, 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 does not support the add or addAll operations.

      The difference between this method and entrySet is that entrySet's iterator() method returns an iterator that iterates over the mappings in ascending order by key. This method's iterator method iterates over the mappings in ascending order by value.

      Returns:
      a set view of the mappings contained in this map.
    • keySetByValue

      public Set keySetByValue()
      Deprecated.
      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, 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 does not support the add or addAll operations.

      The difference between this method and keySet is that keySet's iterator() method returns an iterator that iterates over the keys in ascending order by key. This method's iterator method iterates over the keys in ascending order by value.

      Returns:
      a set view of the keys contained in this map.
    • valuesByValue

      public Collection valuesByValue()
      Deprecated.
      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, 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 does not support the add or addAll operations.

      The difference between this method and values is that values's iterator() method returns an iterator that iterates over the values in ascending order by key. This method's iterator method iterates over the values in ascending order by key.

      Returns:
      a collection view of the values contained in this map.
    • doRemove

      private Object doRemove(Comparable o, int index)
      Deprecated.
      common remove logic (remove by key or remove by value)
      Parameters:
      o - the key, or value, that we're looking for
      index - KEY or VALUE
      Returns:
      the key, if remove by value, or the value, if remove by key. null if the specified key or value could not be found
    • doGet

      private Object doGet(Comparable o, int index)
      Deprecated.
      common get logic, used to get by key or get by value
      Parameters:
      o - the key or value that we're looking for
      index - KEY or VALUE
      Returns:
      the key (if the value was mapped) or the value (if the key was mapped); null if we couldn't find the specified object
    • oppositeIndex

      private int oppositeIndex(int index)
      Deprecated.
      Get the opposite index of the specified index
      Parameters:
      index - KEY or VALUE
      Returns:
      VALUE (if KEY was specified), else KEY
    • lookup

      private DoubleOrderedMap.Node lookup(Comparable data, int index)
      Deprecated.
      do the actual lookup of a piece of data
      Parameters:
      data - the key or value to be looked up
      index - KEY or VALUE
      Returns:
      the desired Node, or null if there is no mapping of the specified data
    • compare

      private static int compare(Comparable o1, Comparable o2)
      Deprecated.
      Compare two objects
      Parameters:
      o1 - the first object
      o2 - the second object
      Returns:
      negative value if o1 invalid input: '<' o2; 0 if o1 == o2; positive value if o1 > o2
    • leastNode

      private static DoubleOrderedMap.Node leastNode(DoubleOrderedMap.Node node, int index)
      Deprecated.
      find the least node from a given node. very useful for starting a sorting iterator ...
      Parameters:
      node - the node from which we will start searching
      index - KEY or VALUE
      Returns:
      the smallest node, from the specified node, in the specified mapping
    • nextGreater

      private DoubleOrderedMap.Node nextGreater(DoubleOrderedMap.Node node, int index)
      Deprecated.
      get the next larger node from the specified node
      Parameters:
      node - the node to be searched from
      index - KEY or VALUE
      Returns:
      the specified node
    • copyColor

      private static void copyColor(DoubleOrderedMap.Node from, DoubleOrderedMap.Node to, int index)
      Deprecated.
      copy the color from one node to another, dealing with the fact that one or both nodes may, in fact, be null
      Parameters:
      from - the node whose color we're copying; may be null
      to - the node whose color we're changing; may be null
      index - KEY or VALUE
    • isRed

      private static boolean isRed(DoubleOrderedMap.Node node, int index)
      Deprecated.
      is the specified node red? if the node does not exist, no, it's black, thank you
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • isBlack

      private static boolean isBlack(DoubleOrderedMap.Node node, int index)
      Deprecated.
      is the specified black red? if the node does not exist, sure, it's black, thank you
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • makeRed

      private static void makeRed(DoubleOrderedMap.Node node, int index)
      Deprecated.
      force a node (if it exists) red
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • makeBlack

      private static void makeBlack(DoubleOrderedMap.Node node, int index)
      Deprecated.
      force a node (if it exists) black
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • getGrandParent

      private static DoubleOrderedMap.Node getGrandParent(DoubleOrderedMap.Node node, int index)
      Deprecated.
      get a node's grandparent. mind you, the node, its parent, or its grandparent may not exist. no problem
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • getParent

      private static DoubleOrderedMap.Node getParent(DoubleOrderedMap.Node node, int index)
      Deprecated.
      get a node's parent. mind you, the node, or its parent, may not exist. no problem
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • getRightChild

      private static DoubleOrderedMap.Node getRightChild(DoubleOrderedMap.Node node, int index)
      Deprecated.
      get a node's right child. mind you, the node may not exist. no problem
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • getLeftChild

      private static DoubleOrderedMap.Node getLeftChild(DoubleOrderedMap.Node node, int index)
      Deprecated.
      get a node's left child. mind you, the node may not exist. no problem
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • isLeftChild

      private static boolean isLeftChild(DoubleOrderedMap.Node node, int index)
      Deprecated.
      is this node its parent's left child? mind you, the node, or its parent, may not exist. no problem. if the node doesn't exist ... it's its non-existent parent's left child. If the node does exist but has no parent ... no, we're not the non-existent parent's left child. Otherwise (both the specified node AND its parent exist), check.
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • isRightChild

      private static boolean isRightChild(DoubleOrderedMap.Node node, int index)
      Deprecated.
      is this node its parent's right child? mind you, the node, or its parent, may not exist. no problem. if the node doesn't exist ... it's its non-existent parent's right child. If the node does exist but has no parent ... no, we're not the non-existent parent's right child. Otherwise (both the specified node AND its parent exist), check.
      Parameters:
      node - the node (may be null) in question
      index - KEY or VALUE
    • rotateLeft

      private void rotateLeft(DoubleOrderedMap.Node node, int index)
      Deprecated.
      do a rotate left. standard fare in the world of balanced trees
      Parameters:
      node - the node to be rotated
      index - KEY or VALUE
    • rotateRight

      private void rotateRight(DoubleOrderedMap.Node node, int index)
      Deprecated.
      do a rotate right. standard fare in the world of balanced trees
      Parameters:
      node - the node to be rotated
      index - KEY or VALUE
    • doRedBlackInsert

      private void doRedBlackInsert(DoubleOrderedMap.Node insertedNode, int index)
      Deprecated.
      complicated red-black insert stuff. Based on Sun's TreeMap implementation, though it's barely recognizable any more
      Parameters:
      insertedNode - the node to be inserted
      index - KEY or VALUE
    • doRedBlackDelete

      private void doRedBlackDelete(DoubleOrderedMap.Node deletedNode)
      Deprecated.
      complicated red-black delete stuff. Based on Sun's TreeMap implementation, though it's barely recognizable any more
      Parameters:
      deletedNode - the node to be deleted
    • doRedBlackDeleteFixup

      private void doRedBlackDeleteFixup(DoubleOrderedMap.Node replacementNode, int index)
      Deprecated.
      complicated red-black delete stuff. Based on Sun's TreeMap implementation, though it's barely recognizable any more. This rebalances the tree (somewhat, as red-black trees are not perfectly balanced -- perfect balancing takes longer)
      Parameters:
      replacementNode - the node being replaced
      index - KEY or VALUE
    • swapPosition

      private void swapPosition(DoubleOrderedMap.Node x, DoubleOrderedMap.Node y, int index)
      Deprecated.
      swap two nodes (except for their content), taking care of special cases where one is the other's parent ... hey, it happens.
      Parameters:
      x - one node
      y - another node
      index - KEY or VALUE
    • checkNonNullComparable

      private static void checkNonNullComparable(Object o, int index)
      Deprecated.
      check if an object is fit to be proper input ... has to be Comparable and non-null
      Parameters:
      o - the object being checked
      index - KEY or VALUE (used to put the right word in the exception message)
      Throws:
      NullPointerException - if o is null
      ClassCastException - if o is not Comparable
    • checkKey

      private static void checkKey(Object key)
      Deprecated.
      check a key for validity (non-null and implements Comparable)
      Parameters:
      key - the key to be checked
      Throws:
      NullPointerException - if key is null
      ClassCastException - if key is not Comparable
    • checkValue

      private static void checkValue(Object value)
      Deprecated.
      check a value for validity (non-null and implements Comparable)
      Parameters:
      value - the value to be checked
      Throws:
      NullPointerException - if value is null
      ClassCastException - if value is not Comparable
    • checkKeyAndValue

      private static void checkKeyAndValue(Object key, Object value)
      Deprecated.
      check a key and a value for validity (non-null and implements Comparable)
      Parameters:
      key - the key to be checked
      value - the value to be checked
      Throws:
      NullPointerException - if key or value is null
      ClassCastException - if key or value is not Comparable
    • modify

      private void modify()
      Deprecated.
      increment the modification count -- used to check for concurrent modification of the map through the map and through an Iterator from one of its Set or Collection views
    • grow

      private void grow()
      Deprecated.
      bump up the size and note that the map has changed
    • shrink

      private void shrink()
      Deprecated.
      decrement the size and note that the map has changed
    • insertValue

      private void insertValue(DoubleOrderedMap.Node newNode) throws IllegalArgumentException
      Deprecated.
      insert a node by its value
      Parameters:
      newNode - the node to be inserted
      Throws:
      IllegalArgumentException - if the node already exists in the value mapping
    • size

      public int size()
      Deprecated.
      Returns the number of key-value mappings in this map. If the map contains more than Integer.MAXVALUE elements, returns Integer.MAXVALUE.
      Specified by:
      size in interface Map
      Overrides:
      size in class AbstractMap
      Returns:
      the number of key-value mappings in this map.
    • containsKey

      public boolean containsKey(Object key) throws ClassCastException, NullPointerException
      Deprecated.
      Returns true if this map contains a mapping for the specified key.
      Specified by:
      containsKey in interface Map
      Overrides:
      containsKey in class AbstractMap
      Parameters:
      key - key whose presence in this map is to be tested.
      Returns:
      true if this map contains a mapping for the specified key.
      Throws:
      ClassCastException - if the key is of an inappropriate type for this map.
      NullPointerException - if the key is null
    • containsValue

      public boolean containsValue(Object value)
      Deprecated.
      Returns true if this map maps one or more keys to the specified value.
      Specified by:
      containsValue in interface Map
      Overrides:
      containsValue in class AbstractMap
      Parameters:
      value - value whose presence in this map is to be tested.
      Returns:
      true if this map maps one or more keys to the specified value.
    • get

      Deprecated.
      Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key.
      Specified by:
      get in interface Map
      Overrides:
      get in class AbstractMap
      Parameters:
      key - key whose associated value is to be returned.
      Returns:
      the value to which this map maps the specified key, or null if the map contains no mapping for this key.
      Throws:
      ClassCastException - if the key is of an inappropriate type for this map.
      NullPointerException - if the key is null
    • put

      Deprecated.
      Associates the specified value with the specified key in this map.
      Specified by:
      put in interface Map
      Overrides:
      put in class AbstractMap
      Parameters:
      key - key with which the specified value is to be associated.
      value - value to be associated with the specified key.
      Returns:
      null
      Throws:
      ClassCastException - if the class of the specified key or value prevents it from being stored in this map.
      NullPointerException - if the specified key or value is null
      IllegalArgumentException - if the key duplicates an existing key, or if the value duplicates an existing value
    • remove

      public Object remove(Object key)
      Deprecated.
      Removes the mapping for this key from this map if present
      Specified by:
      remove in interface Map
      Overrides:
      remove in class AbstractMap
      Parameters:
      key - key whose mapping is to be removed from the map.
      Returns:
      previous value associated with specified key, or null if there was no mapping for key.
    • clear

      public void clear()
      Deprecated.
      Removes all mappings from this map
      Specified by:
      clear in interface Map
      Overrides:
      clear in class AbstractMap
    • keySet

      public Set keySet()
      Deprecated.
      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, 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 does not support the add or addAll operations.
      Specified by:
      keySet in interface Map
      Overrides:
      keySet in class AbstractMap
      Returns:
      a set view of the keys contained in this map.
    • values

      public Collection values()
      Deprecated.
      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, 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 does not support the add or addAll operations.
      Specified by:
      values in interface Map
      Overrides:
      values in class AbstractMap
      Returns:
      a collection view of the values contained in this map.
    • entrySet

      public Set entrySet()
      Deprecated.
      Returns a set view of the mappings contained in this map. Each element in the returned set is a Map.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, 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 does not support the add or addAll operations. The setValue method is not supported on the Map Entry.

      Specified by:
      entrySet in interface Map
      Specified by:
      entrySet in class AbstractMap
      Returns:
      a set view of the mappings contained in this map.