Package org.geotools.util

Class DerivedSet<B,E>

Object

AbstractCollection<E>

AbstractSet<E>

DerivedSet<B,E>

Type Parameters:

B - The type of elements in the backing set.

E - The type of elements in this set.

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, Set<E>, CheckedCollection<E>

public abstract class DerivedSet<B,E>
extends AbstractSet<E>
implements CheckedCollection<E>, Serializable

A set whose values are derived from an other set. The values are derived only when requested, which make it possible to backup potentially large sets. Implementations need only to overrides baseToDerived(B) and derivedToBase(E) methods. This set do not supports null value, since null is used when no mapping from base to this exists. This class is serializable if the underlying base set is serializable too.

This class is not thread-safe. Synchronizations (if wanted) are user's reponsability.

Since:

2.0

Author:

Martin Desruisseaux (IRD)

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected Set<B>	base	The base set whose values are derived from.

Constructor Summary

Constructors

Constructor	Description
DerivedSet(Set<B> base, Class<E> derivedType)	Creates a new derived set from the specified base set.

Method Summary

Modifier and Type	Method	Description
boolean	add(E element)	Ensures that this set contains the specified element.
protected abstract E	baseToDerived(B element)	Transforms a value in the base set to a value in this set.
boolean	contains(Object element)	Returns true if this set contains the specified element.
protected abstract B	derivedToBase(E element)	Transforms a value in this set to a value in the base set.
Class<E>	getElementType()	Returns the derived element type.
boolean	isEmpty()	Returns true if this set contains no elements.
Iterator<E>	iterator()	Returns an iterator over the elements contained in this set.
boolean	remove(Object element)	Removes a single instance of the specified element from this set.
int	size()	Returns the number of elements in this set.

Methods inherited from class AbstractSet

equals, hashCode, removeAll

Methods inherited from class AbstractCollection

addAll, clear, containsAll, retainAll, toArray, toArray, toString

Methods inherited from class Object

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

Methods inherited from interface Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface Iterable

forEach

Methods inherited from interface Set

addAll, clear, containsAll, retainAll, spliterator, toArray, toArray

Field Detail

base

protected final Set<B> base

The base set whose values are derived from.

See Also:

baseToDerived(B), derivedToBase(E)

Constructor Detail

DerivedSet

public DerivedSet(Set<B> base,
                  Class<E> derivedType)

Creates a new derived set from the specified base set.

Parameters:

base - The base set.

derivedType - The type of elements in this derived set.

Since:

2.5

Method Detail

getElementType

public Class<E> getElementType()

Returns the derived element type.

Specified by:

getElementType in interface CheckedCollection<B>

Returns:

The element type.

Since:

2.5

baseToDerived

protected abstract E baseToDerived(B element)

Transforms a value in the base set to a value in this set. If there is no mapping in the derived set for the specified element, then this method returns null.

Parameters:

element - A value in the base set.

Returns:

The value that this view should contains instead of element, or null.

derivedToBase

protected abstract B derivedToBase(E element)

Transforms a value in this set to a value in the base set.

Parameters:

element - A value in this set.

Returns:

The value stored in the base set.

iterator

public Iterator<E> iterator()

Returns an iterator over the elements contained in this set. The iterator will invokes baseToDerived(B) for each element.

Specified by:

iterator in interface Collection<B>

Specified by:

iterator in interface Iterable<B>

Specified by:

iterator in interface Set<B>

Specified by:

iterator in class AbstractCollection<E>

Returns:

an iterator over the elements contained in this set.

size

public int size()

Returns the number of elements in this set. The default implementation counts the number of elements returned by the iterator.

Specified by:

size in interface Collection<B>

Specified by:

size in interface Set<B>

Specified by:

size in class AbstractCollection<E>

Returns:

the number of elements in this set.

isEmpty

public boolean isEmpty()

Returns true if this set contains no elements.

Specified by:

isEmpty in interface Collection<B>

Specified by:

isEmpty in interface Set<B>

Overrides:

isEmpty in class AbstractCollection<E>

Returns:

true if this set contains no elements.

contains

public boolean contains(Object element)

Returns true if this set contains the specified element. The default implementation invokes base.contains(derivedToBase(element)) .

Specified by:

contains in interface Collection<B>

Specified by:

contains in interface Set<B>

Overrides:

contains in class AbstractCollection<E>

Parameters:

element - object to be checked for containment in this set.

Returns:

true if this set contains the specified element.

add

public boolean add(E element)
            throws UnsupportedOperationException

Ensures that this set contains the specified element. The default implementation invokes base.add(derivedToBase(element)).

Specified by:

add in interface Collection<B>

Specified by:

add in interface Set<B>

Overrides:

add in class AbstractCollection<E>

Parameters:

element - element whose presence in this set is to be ensured.

Returns:

true if the set changed as a result of the call.

Throws:

UnsupportedOperationException - if the base set doesn't supports the add operation.

remove

public boolean remove(Object element)
               throws UnsupportedOperationException

Removes a single instance of the specified element from this set. The default implementation invokes base.remove(derivedToBase(element)) .

Specified by:

remove in interface Collection<B>

Specified by:

remove in interface Set<B>

Overrides:

remove in class AbstractCollection<E>

Parameters:

element - element to be removed from this set, if present.

Returns:

true if the set contained the specified element.

Throws:

UnsupportedOperationException - if the base set doesn't supports the remove operation.