org.geotools.feature.collection
Class AbstractFeatureCollection

Object
  AbstractFeatureCollection

All Implemented Interfaces:

SimpleFeatureCollection, FeatureCollection<SimpleFeatureType,SimpleFeature>

Direct Known Subclasses:

ForceCoordinateSystemFeatureResults, ListFeatureCollection, MemoryFeatureCollection, ReprojectFeatureResults, SubFeatureCollection

public abstract class AbstractFeatureCollection
extends Object
implements SimpleFeatureCollection

Implement a feature collection just based on provision of iterator.

Author:

Jody Garnett (Refractions Research Inc)

Field Summary

protected String	id id used when serialized to gml
protected List<CollectionListener>	listeners listeners
protected Set	open Set of open resource iterators
protected SimpleFeatureType	schema

Constructor Summary

protected

AbstractFeatureCollection(SimpleFeatureType memberType)

Method Summary

void	accepts(FeatureVisitor visitor, ProgressListener progress) Visit the contents of a feature collection.
boolean	add(SimpleFeature o) Implement to support modification.
boolean	addAll(Collection<? extends SimpleFeature> c) Adds all of the elements in the specified collection to this collection (optional operation).
boolean	addAll(FeatureCollection<? extends SimpleFeatureType,? extends SimpleFeature> c)
void	addListener(CollectionListener listener) Adds a listener for collection events.
void	clear() Removes all of the elements from this collection (optional operation).
void	close(FeatureIterator<SimpleFeature> close) Clean up after any resources associated with this FeatureIterator in a manner similar to JDO collections.
void	close(Iterator close) Clean up after any resources associated with this iteartor in a manner similar to JDO collections.
protected abstract void	closeIterator(Iterator<SimpleFeature> close) Please override to cleanup after your own iterators, and any used resources.
boolean	contains(Object o) Returns true if this collection contains the specified element.
boolean	containsAll(Collection<?> c) Returns true if this collection contains all of the elements in the specified collection.
SimpleFeatureIterator	features() Obtain a FeatureIterator of the Features within this collection.
abstract ReferencedEnvelope	getBounds() Subclasses need to override this.
String	getID() ID used when serializing to GML
Set	getOpenIterators() Returns the set of open iterators.
SimpleFeatureType	getSchema() The schema for the child feature members of this collection.
boolean	isEmpty()
Iterator<SimpleFeature>	iterator() Please implement!
protected abstract Iterator<SimpleFeature>	openIterator() Open a resource based Iterator, we will call close( iterator ).
void	purge() Close any outstanding resources released by this resources.
boolean	remove(Object o) Removes a single instance of the specified element from this collection, if it is present (optional operation).
boolean	removeAll(Collection<?> c) Removes from this collection all of its elements that are contained in the specified collection (optional operation).
void	removeListener(CollectionListener listener) Removes a listener for collection events.
boolean	retainAll(Collection<?> c) Retains only the elements in this collection that are contained in the specified collection (optional operation).
abstract int	size() Returns the number of elements in this collection.
SimpleFeatureCollection	sort(SortBy order) Obtained sorted contents.
SimpleFeatureCollection	subCollection(Filter filter) SimpleFeatureCollection "view" indicated by provided filter.
SimpleFeatureCollection	subList(Filter filter)
Object[]	toArray() Array of all the elements.
<T> T[]	toArray(T[] a)

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

listeners

protected List<CollectionListener> listeners

listeners

id

protected String id

id used when serialized to gml

schema

protected SimpleFeatureType schema

open

protected final Set open

Set of open resource iterators

Constructor Detail

AbstractFeatureCollection

protected AbstractFeatureCollection(SimpleFeatureType memberType)

Method Detail

features

public SimpleFeatureIterator features()

Description copied from interface: FeatureCollection

Obtain a FeatureIterator of the Features within this collection.

The implementation of Collection must adhere to the rules of fail-fast concurrent modification. In addition (to allow for resource backed collections, the close( Iterator ) method must be called.

This is almost equivalent to:

• a Type-Safe call to: getAttribute(getFeatureType().getAttributeType(0).getName()).iterator();.
• A Java 5:Iterator<Feature>

Example (safe) use:

 FeatureIterator iterator=collection.features();
 try {
     while( iterator.hasNext()  ){
          Feature feature = iterator.next();
          System.out.println( feature.getID() );
     }
 }
 finally {
     collection.close( iterator );
 }
 

GML Note: The contents of this iterator are considered to be defined by featureMember tags (and/or the single allowed FeatureMembers tag). Please see getFeatureType for more details.

Specified by:

features in interface SimpleFeatureCollection

Specified by:

features in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Returns:

A FeatureIterator.

close

public final void close(Iterator close)

Clean up after any resources associated with this iteartor in a manner similar to JDO collections.

Example (safe) use:

 Iterator iterator = collection.iterator();
 try {
     for( Iterator i=collection.iterator(); i.hasNext();){
          Feature feature = (Feature) i.hasNext();
          System.out.println( feature.getID() );
     }
 }
 finally {
     collection.close( iterator );
 }
 

Specified by:

close in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

close -

close

public void close(FeatureIterator<SimpleFeature> close)

Description copied from interface: FeatureCollection

Clean up after any resources associated with this FeatureIterator in a manner similar to JDO collections.

Example (safe) use:

 Iterator iterator = collection.iterator();
 try {
     for( Iterator i=collection.iterator(); i.hasNext();){
          Feature feature = i.hasNext();
          System.out.println( feature.getID() );
     }
 }
 finally {
     collection.close( iterator );
 }
 

Specified by:

close in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

openIterator

protected abstract Iterator<SimpleFeature> openIterator()

Open a resource based Iterator, we will call close( iterator ).

Please subclass to provide your own iterator for the the ResourceCollection, note iterator() is implemented to call open() and track the results in for later purge().

Returns:

Iterator based on resource use

closeIterator

protected abstract void closeIterator(Iterator<SimpleFeature> close)

Please override to cleanup after your own iterators, and any used resources.

As an example if the iterator was working off a File then the inputstream should be closed.

Subclass must call super.close( close ) to allow the list of open iterators to be adjusted.

Parameters:

close - Iterator, will not be null

purge

public void purge()

Close any outstanding resources released by this resources.

This method should be used with great caution, it is however available to allow the use of the ResourceCollection with algorthims that are unaware of the need to close iterators after use.

Example of using a normal Collections utility method:

 Collections.sort( collection );
 collection.purge(); 
 

Specified by:

purge in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

size

public abstract int size()

Returns the number of elements in this collection.

Specified by:

size in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Returns:

Number of items, or Interger.MAX_VALUE

See Also:

Collection.size()

add

public boolean add(SimpleFeature o)

Implement to support modification.

Specified by:

add in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

o - element whose presence in this collection is to be ensured.

Returns:

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

Throws:

UnsupportedOperationException - if the add method is not supported by this collection.

NullPointerException - if this collection does not permit null elements, and the specified element is null.

ClassCastException - if the class of the specified element prevents it from being added to this collection.

IllegalArgumentException - if some aspect of this element prevents it from being added to this collection.

See Also:

Collection.add(Object)

addAll

public boolean addAll(Collection<? extends SimpleFeature> c)

Adds all of the elements in the specified collection to this collection (optional operation).

Specified by:

addAll in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

c - collection whose elements are to be added to this collection.

Returns:

true if this collection changed as a result of the call.

Throws:

UnsupportedOperationException - if this collection does not support the addAll method.

NullPointerException - if the specified collection is null.

See Also:

#add(Object)

addAll

public boolean addAll(FeatureCollection<? extends SimpleFeatureType,? extends SimpleFeature> c)

Specified by:

addAll in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

See Also:

FeatureCollection.addAll(Collection)

clear

public void clear()

Removes all of the elements from this collection (optional operation).

Specified by:

clear in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Throws:

UnsupportedOperationException - if the clear method is not supported by this collection.

See Also:

Collection.clear()

contains

public boolean contains(Object o)

Returns true if this collection contains the specified element. .

This implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.

Specified by:

contains in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

o - object to be checked for containment in this collection.

Returns:

true if this collection contains the specified element.

See Also:

Collection.contains(Object)

containsAll

public boolean containsAll(Collection<?> c)

Returns true if this collection contains all of the elements in the specified collection.

Specified by:

containsAll in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

c - collection to be checked for containment in this collection.

Returns:

true if this collection contains all of the elements in the specified collection.

Throws:

NullPointerException - if the specified collection is null.

See Also:

contains(Object)

getOpenIterators

public final Set getOpenIterators()

Returns the set of open iterators.

Contents are a mix of Iterator and SimpleFeatureIterator

iterator

public final Iterator<SimpleFeature> iterator()

Please implement!

Note: If you return a ResourceIterator, the default implemntation of close( Iterator ) will know what to do.

Specified by:

iterator in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Returns:

Iterator

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Returns:

true if this collection contains no elements.

See Also:

Collection.isEmpty()

remove

public boolean remove(Object o)

Removes a single instance of the specified element from this collection, if it is present (optional operation).

Specified by:

remove in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

o - element to be removed from this collection, if present.

Returns:

true if the collection contained the specified element.

Throws:

UnsupportedOperationException - if the remove method is not supported by this collection.

See Also:

Collection.remove(Object)

removeAll

public final boolean removeAll(Collection<?> c)

Removes from this collection all of its elements that are contained in the specified collection (optional operation).

Specified by:

removeAll in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

c - elements to be removed from this collection.

Returns:

true if this collection changed as a result of the call.

Throws:

UnsupportedOperationException - if the removeAll method is not supported by this collection.

NullPointerException - if the specified collection is null.

See Also:

remove(Object), contains(Object)

retainAll

public final boolean retainAll(Collection<?> c)

Retains only the elements in this collection that are contained in the specified collection (optional operation).

Specified by:

retainAll in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

c - elements to be retained in this collection.

Returns:

true if this collection changed as a result of the call.

Throws:

UnsupportedOperationException - if the retainAll method is not supported by this Collection.

NullPointerException - if the specified collection is null.

See Also:

remove(Object), contains(Object)

toArray

public Object[] toArray()

Array of all the elements.

Specified by:

toArray in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Returns:

an array containing all of the elements in this collection.

See Also:

Collection.toArray()

toArray

public <T> T[] toArray(T[] a)

Specified by:

toArray in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

See Also:

Collection.toArray(Object[])

accepts

public void accepts(FeatureVisitor visitor,
                    ProgressListener progress)

Description copied from interface: FeatureCollection

Visit the contents of a feature collection.

The order of traversal is dependent on the FeatureCollection implementation; some collections are able to make efficient use of an internal index in order to quickly visit features located in the same region.

Specified by:

accepts in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

visitor - Closure applied to each feature in turn.

progress - Used to report progress, may be used to interrupt the operation

subList

public SimpleFeatureCollection subList(Filter filter)

subCollection

public SimpleFeatureCollection subCollection(Filter filter)

Description copied from interface: FeatureCollection

SimpleFeatureCollection "view" indicated by provided filter.

The contents of the returned SimpleFeatureCollection are determined by applying the provider Filter to the entire contents of this FeatureCollection. The result is "live" and modifications will be shared.

This method is used cut down on the number of filter based methods required for a useful SimpleFeatureCollection construct. The FeatureCollections returned really should be considered as a temporary "view" used to control the range of a removeAll, or modify operation.

Example Use:

 collection.subCollection( filter ).clear();
 

The above recommended use is agreement with the Collections API precident of List.subList( start, end ).

The results of subCollection:

• are to be considered unordered
• may be an ordered FeatureList if requested when sortBy is indicated

Specified by:

subCollection in interface SimpleFeatureCollection

Specified by:

subCollection in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Returns:

SimpleFeatureCollection identified as subset.

See Also:

FeatureList

sort

public SimpleFeatureCollection sort(SortBy order)

Description copied from interface: FeatureCollection

Obtained sorted contents.

This method may not be supported by all implementations, consider the use of FeatureSource.features( Query ).

Specified by:

sort in interface SimpleFeatureCollection

Specified by:

sort in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

order - Sort order

Returns:

FeatureCollection sorted in the indicated order

getID

public String getID()

Description copied from interface: FeatureCollection

ID used when serializing to GML

Specified by:

getID in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

addListener

public final void addListener(CollectionListener listener)
                       throws NullPointerException

Description copied from interface: FeatureCollection

Adds a listener for collection events.

When this collection is backed by live data the event notification will follow the guidelines outlined by FeatureListner.

Specified by:

addListener in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

listener - The listener to add

Throws:

NullPointerException - If the listener is null.

removeListener

public final void removeListener(CollectionListener listener)
                          throws NullPointerException

Description copied from interface: FeatureCollection

Removes a listener for collection events.

Specified by:

removeListener in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Parameters:

listener - The listener to remove

Throws:

NullPointerException - If the listener is null.

getSchema

public SimpleFeatureType getSchema()

Description copied from interface: FeatureCollection

The schema for the child feature members of this collection.

Represents the most general FeatureType in common to all the features in this collection.

• For a collection backed by a shapefiles (or database tables) the FeatureType returned by getSchema() will complete describe each and every child in the collection.
• For mixed content FeatureCollections you will need to check the FeatureType of each Feature as it is retrived from the collection
• The degenerate case returns the "_Feature" FeatureType, where the only thing known is that the contents are Features.

Specified by:

getSchema in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Returns:

FeatureType describing the "common" schema to all child features of this collection

getBounds

public abstract ReferencedEnvelope getBounds()

Subclasses need to override this.

Specified by:

getBounds in interface FeatureCollection<SimpleFeatureType,SimpleFeature>

Returns:

An Envelope containing the total bounds of this collection.