Package org.apache.commons.collections4.multiset

Class AbstractMultiSet<E>

java.lang.Object

java.util.AbstractCollection<E>

org.apache.commons.collections4.multiset.AbstractMultiSet<E>

Type Parameters:

E - the type held in the multiset

All Implemented Interfaces:

Iterable<E>, Collection<E>, MultiSet<E>

Direct Known Subclasses:

AbstractMapMultiSet

public abstract class AbstractMultiSet<E>
extends AbstractCollection<E>
implements MultiSet<E>

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

Since:

4.1

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	AbstractMultiSet.AbstractEntry<E>	Inner class AbstractEntry.
protected static class	AbstractMultiSet.EntrySet<E>	Inner class EntrySet.
protected static class	AbstractMultiSet.UniqueSet<E>	Inner class UniqueSet.

Nested classes/interfaces inherited from interface org.apache.commons.collections4.MultiSet

MultiSet.Entry<E>

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractMultiSet()	Constructor needed for subclass serialisation.

Method Summary

Modifier and Type	Method	Description
boolean	add(E object)	Adds one copy of the specified object to the MultiSet.
int	add(E object, int occurrences)	Adds a number of occurrences of the specified object to the MultiSet.
void	clear()	Clears the multiset removing all elements from the entrySet.
boolean	contains(Object object)	Determines if the multiset contains the given element.
protected Set<MultiSet.Entry<E>>	createEntrySet()	Create a new view for the set of entries in this multiset.
protected abstract Iterator<MultiSet.Entry<E>>	createEntrySetIterator()	Creates an entry set iterator.
protected Set<E>	createUniqueSet()	Create a new view for the set of unique elements in this multiset.
protected Iterator<E>	createUniqueSetIterator()	Creates a unique set iterator.
protected void	doReadObject(ObjectInputStream in)	Read the multiset in using a custom routine.
protected void	doWriteObject(ObjectOutputStream out)	Write the multiset out using a custom routine.
Set<MultiSet.Entry<E>>	entrySet()	Returns an unmodifiable view of the entries of this multiset.
boolean	equals(Object object)	Compares this MultiSet to another object.
int	getCount(Object object)	Returns the number of occurrence of the given element in this multiset by iterating over its entrySet.
int	hashCode()	Gets a hash code for the MultiSet compatible with the definition of equals.
Iterator<E>	iterator()	Gets an iterator over the multiset elements.
boolean	remove(Object object)	Removes one occurrence of the given object from the MultiSet.
int	remove(Object object, int occurrences)	Removes a number of occurrences of the specified object from the MultiSet.
boolean	removeAll(Collection<?> coll)	Remove all occurrences of all elements from this MultiSet represented in the given collection.
int	setCount(E object, int count)	Sets the number of occurrences of the specified object in the MultiSet to the given count.
int	size()	Returns the number of elements in this multiset.
String	toString()	Implement a toString() method suitable for debugging.
protected abstract int	uniqueElements()	Returns the number of unique elements in this multiset.
Set<E>	uniqueSet()	Returns a view of the unique elements of this multiset.

Methods inherited from class java.util.AbstractCollection

addAll, containsAll, isEmpty, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

addAll, isEmpty, parallelStream, removeIf, spliterator, stream, toArray, toArray, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface org.apache.commons.collections4.MultiSet

containsAll, retainAll

Constructor Detail

AbstractMultiSet

protected AbstractMultiSet()

Constructor needed for subclass serialisation.

Method Detail

size

public int size()

Returns the number of elements in this multiset.

Specified by:

size in interface Collection<E>

Specified by:

size in interface MultiSet<E>

Specified by:

size in class AbstractCollection<E>

Returns:

current size of the multiset

getCount

public int getCount(Object object)

Returns the number of occurrence of the given element in this multiset by iterating over its entrySet.

Specified by:

getCount in interface MultiSet<E>

Parameters:

object - the object to search for

Returns:

the number of occurrences of the object, zero if not found

setCount

public int setCount(E object,
                    int count)

Description copied from interface: MultiSet

Sets the number of occurrences of the specified object in the MultiSet to the given count.

If the provided count is zero, the object will be removed from the MultiSet.uniqueSet().

Specified by:

setCount in interface MultiSet<E>

Parameters:

object - the object to update

count - the number of occurrences of the object

Returns:

the number of occurrences of the object before this operation, zero if the object was not contained in the multiset

contains

public boolean contains(Object object)

Determines if the multiset contains the given element.

Specified by:

contains in interface Collection<E>

Overrides:

contains in class AbstractCollection<E>

Parameters:

object - the object to search for

Returns:

true if the multiset contains the given element

iterator

public Iterator<E> iterator()

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

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface MultiSet<E>

Specified by:

iterator in class AbstractCollection<E>

Returns:

the iterator

add

public boolean add(E object)

Description copied from interface: MultiSet

Adds one copy of the specified object to the MultiSet.

If the object is already in the MultiSet.uniqueSet() then increment its count as reported by MultiSet.getCount(Object). Otherwise add it to the MultiSet.uniqueSet() and report its count as 1.

Specified by:

add in interface Collection<E>

Specified by:

add in interface MultiSet<E>

Overrides:

add in class AbstractCollection<E>

Parameters:

object - the object to add

Returns:

true always, as the size of the MultiSet is increased in any case

add

public int add(E object,
               int occurrences)

Description copied from interface: MultiSet

Adds a number of occurrences of the specified object to the MultiSet.

If the object is already in the MultiSet.uniqueSet() then increment its count as reported by MultiSet.getCount(Object). Otherwise add it to the MultiSet.uniqueSet() and report its count as occurrences.

Specified by:

add in interface MultiSet<E>

Parameters:

object - the object to add

occurrences - the number of occurrences to add, may be zero, in which case no change is made to the multiset

Returns:

the number of occurrences of the object in the multiset before this operation; possibly zero

clear

public void clear()

Clears the multiset removing all elements from the entrySet.

Specified by:

clear in interface Collection<E>

Overrides:

clear in class AbstractCollection<E>

remove

public boolean remove(Object object)

Description copied from interface: MultiSet

Removes one occurrence of the given object from the MultiSet.

If the number of occurrences after this operations is reduced to zero, the object will be removed from the MultiSet.uniqueSet().

Specified by:

remove in interface Collection<E>

Specified by:

remove in interface MultiSet<E>

Overrides:

remove in class AbstractCollection<E>

Parameters:

object - the object to remove

Returns:

true if this call changed the collection

remove

public int remove(Object object,
                  int occurrences)

Description copied from interface: MultiSet

Removes a number of occurrences of the specified object from the MultiSet.

If the number of occurrences to remove is greater than the actual number of occurrences in the multiset, the object will be removed from the multiset.

Specified by:

remove in interface MultiSet<E>

Parameters:

object - the object to remove

occurrences - the number of occurrences to remove, may be zero, in which case no change is made to the multiset

Returns:

the number of occurrences of the object in the multiset before the operation; possibly zero

removeAll

public boolean removeAll(Collection<?> coll)

Description copied from interface: MultiSet

Remove all occurrences of all elements from this MultiSet represented in the given collection.

Specified by:

removeAll in interface Collection<E>

Specified by:

removeAll in interface MultiSet<E>

Overrides:

removeAll in class AbstractCollection<E>

Parameters:

coll - the collection of elements to remove

Returns:

true if this call changed the multiset

uniqueSet

public Set<E> uniqueSet()

Returns a view of the unique elements of this multiset.

Specified by:

uniqueSet in interface MultiSet<E>

Returns:

the set of unique elements in this multiset

createUniqueSet

protected Set<E> createUniqueSet()

Create a new view for the set of unique elements in this multiset.

Returns:

a view of the set of unique elements

createUniqueSetIterator

protected Iterator<E> createUniqueSetIterator()

Creates a unique set iterator. Subclasses can override this to return iterators with different properties.

Returns:

the uniqueSet iterator

entrySet

public Set<MultiSet.Entry<E>> entrySet()

Returns an unmodifiable view of the entries of this multiset.

Specified by:

entrySet in interface MultiSet<E>

Returns:

the set of entries in this multiset

createEntrySet

protected Set<MultiSet.Entry<E>> createEntrySet()

Create a new view for the set of entries in this multiset.

Returns:

a view of the set of entries

uniqueElements

protected abstract int uniqueElements()

Returns the number of unique elements in this multiset.

Returns:

the number of unique elements

createEntrySetIterator

protected abstract Iterator<MultiSet.Entry<E>> createEntrySetIterator()

Creates an entry set iterator. Subclasses can override this to return iterators with different properties.

Returns:

the entrySet iterator

doWriteObject

protected void doWriteObject(ObjectOutputStream out)
                      throws IOException

Write the multiset out using a custom routine.

Parameters:

out - the output stream

Throws:

IOException - any of the usual I/O related exceptions

doReadObject

protected void doReadObject(ObjectInputStream in)
                     throws IOException,
                            ClassNotFoundException

Read the multiset in using a custom routine.

Parameters:

in - the input stream

Throws:

IOException - any of the usual I/O related exceptions

ClassNotFoundException - if the stream contains an object which class can not be loaded

ClassCastException - if the stream does not contain the correct objects

equals

public boolean equals(Object object)

Description copied from interface: MultiSet

Compares this MultiSet to another object.

This MultiSet equals another object if it is also a MultiSet that contains the same number of occurrences of the same elements.

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface MultiSet<E>

Overrides:

equals in class Object

Parameters:

object - the object to compare to

Returns:

true if equal

hashCode

public int hashCode()

Description copied from interface: MultiSet

Gets a hash code for the MultiSet 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).

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface MultiSet<E>

Overrides:

hashCode in class Object

Returns:

the hash code of the MultiSet

toString

public String toString()

Implement a toString() method suitable for debugging.

Overrides:

toString in class AbstractCollection<E>

Returns:

a debugging toString