public abstract class

AbstractMapBag

extends Object
implements Bag
java.lang.Object
   ↳ org.apache.commons.collections.bag.AbstractMapBag
Known Direct Subclasses

Class Overview

Abstract implementation of the Bag interface to simplify the creation of subclass implementations.

Subclasses specify a Map implementation to use as the internal storage. The map will be used to map bag elements to a number; the number represents the number of occurrences of that element in the bag.

Summary

Nested Classes
class AbstractMapBag.MutableInteger Mutable integer class for storing the data. 
Protected Constructors
AbstractMapBag()
Constructor needed for subclass serialisation.
AbstractMapBag(Map map)
Constructor that assigns the specified Map as the backing store.
Public Methods
boolean add(Object object, int nCopies)
Adds a new element to the bag, incrementing its count in the map.
boolean add(Object object)
Adds a new element to the bag, incrementing its count in the underlying map.
boolean addAll(Collection coll)
Invokes add(Object) for each element in the given collection.
void clear()
Clears the bag by clearing the underlying map.
boolean contains(Object object)
Determines if the bag contains the given element by checking if the underlying map contains the element as a key.
boolean containsAll(Collection coll)
Determines if the bag contains the given elements.
boolean equals(Object object)
Compares this Bag to another.
int getCount(Object object)
Returns the number of occurrence of the given element in this bag by looking up its count in the underlying map.
int hashCode()
Gets a hash code for the Bag compatible with the definition of equals.
boolean isEmpty()
Returns true if the underlying map is empty.
Iterator iterator()
Gets an iterator over the bag elements.
boolean remove(Object object, int nCopies)
Removes a specified number of copies of an object from the bag.
boolean remove(Object object)
Removes all copies of the specified object from the bag.
boolean removeAll(Collection coll)
Removes objects from the bag according to their count in the specified collection.
boolean retainAll(Collection coll)
Remove any members of the bag that are not in the given bag, respecting cardinality.
int size()
Returns the number of elements in this bag.
Object[] toArray()
Returns an array of all of this bag's elements.
Object[] toArray(Object[] array)
Returns an array of all of this bag's elements.
String toString()
Implement a toString() method suitable for debugging.
Set uniqueSet()
Returns an unmodifiable view of the underlying map's key set.
Protected Methods
void doReadObject(Map map, ObjectInputStream in)
Read the map in using a custom routine.
void doWriteObject(ObjectOutputStream out)
Write the map out using a custom routine.
Map getMap()
Utility method for implementations to access the map that backs this bag.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.lang.Iterable
From interface java.util.Collection
From interface org.apache.commons.collections.Bag

Protected Constructors

protected AbstractMapBag ()

Constructor needed for subclass serialisation.

protected AbstractMapBag (Map map)

Constructor that assigns the specified Map as the backing store. The map must be empty and non-null.

Parameters
map the map to assign

Public Methods

public boolean add (Object object, int nCopies)

Adds a new element to the bag, incrementing its count in the map.

Parameters
object the object to search for
nCopies the number of copies to add
Returns
  • true if the object was not already in the uniqueSet

public boolean add (Object object)

Adds a new element to the bag, incrementing its count in the underlying map.

Parameters
object the object to add
Returns
  • true if the object was not already in the uniqueSet

public boolean addAll (Collection coll)

Invokes add(Object) for each element in the given collection.

Parameters
coll the collection to add
Returns
  • true if this call changed the bag

public void clear ()

Clears the bag by clearing the underlying map.

public boolean contains (Object object)

Determines if the bag contains the given element by checking if the underlying map contains the element as a key.

Parameters
object the object to search for
Returns
  • true if the bag contains the given element

public boolean containsAll (Collection coll)

Determines if the bag contains the given elements.

Parameters
coll the collection to check against
Returns
  • true if the Bag contains all the collection

public boolean equals (Object object)

Compares this Bag to another. This Bag equals another Bag if it contains the same number of occurrences of the same elements.

Parameters
object the Bag to compare to
Returns
  • true if equal

public int getCount (Object object)

Returns the number of occurrence of the given element in this bag by looking up its count in the underlying map.

Parameters
object the object to search for
Returns
  • the number of occurrences of the object, zero if not found

public int hashCode ()

Gets a hash code for the Bag compatible with the definition of equals. The hash code is defined as the sum total of a hash code for each element. The per element hash code is defined as (e==null ? 0 : e.hashCode()) ^ noOccurances). This hash code is compatible with the Set interface.

Returns
  • the hash code of the Bag

public boolean isEmpty ()

Returns true if the underlying map is empty.

Returns
  • true if bag is empty

public Iterator iterator ()

Gets an iterator over the bag elements. Elements present in the Bag more than once will be returned repeatedly.

Returns
  • the iterator

public boolean remove (Object object, int nCopies)

Removes a specified number of copies of an object from the bag.

Parameters
object the object to remove
nCopies the number of copies to remove
Returns
  • true if the bag changed

public boolean remove (Object object)

Removes all copies of the specified object from the bag.

Parameters
object the object to remove
Returns
  • true if the bag changed

public boolean removeAll (Collection coll)

Removes objects from the bag according to their count in the specified collection.

Parameters
coll the collection to use
Returns
  • true if the bag changed

public boolean retainAll (Collection coll)

Remove any members of the bag that are not in the given bag, respecting cardinality.

Parameters
coll the collection to retain
Returns
  • true if this call changed the collection

public int size ()

Returns the number of elements in this bag.

Returns
  • current size of the bag

public Object[] toArray ()

Returns an array of all of this bag's elements.

Returns
  • an array of all of this bag's elements

public Object[] toArray (Object[] array)

Returns an array of all of this bag's elements.

Parameters
array the array to populate
Returns
  • an array of all of this bag's elements

public String toString ()

Implement a toString() method suitable for debugging.

Returns
  • a debugging toString

public Set uniqueSet ()

Returns an unmodifiable view of the underlying map's key set.

Returns
  • the set of unique elements in this bag

Protected Methods

protected void doReadObject (Map map, ObjectInputStream in)

Read the map in using a custom routine.

Parameters
map the map to use
in the input stream
Throws
IOException
ClassNotFoundException
IOException

protected void doWriteObject (ObjectOutputStream out)

Write the map out using a custom routine.

Parameters
out the output stream
Throws
IOException

protected Map getMap ()

Utility method for implementations to access the map that backs this bag. Not intended for interactive use outside of subclasses.

Returns
  • the map being used by the Bag