Interface FeatureCollection<T extends FeatureType,F extends Feature>
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- All Known Subinterfaces:
RandomFeatureAccess
,SimpleFeatureCollection
,XmlFeatureCollection
- All Known Implementing Classes:
AbstractFeatureCollection
,AdaptorFeatureCollection
,BaseFeatureCollection
,BaseSimpleFeatureCollection
,ClippedFeatureCollection
,ClippingFeatureCollection
,CollectionFeatureSource.SubCollection
,CompositeFeatureCollection
,ContentFeatureCollection
,DataFeatureCollection
,DecoratingFeatureCollection
,DecoratingSimpleFeatureCollection
,DefaultFeatureCollection
,DefaultFeatureResults
,EmptyFeatureCollection
,FilteringFeatureCollection
,FilteringSimpleFeatureCollection
,ForceCoordinateSystemFeatureResults
,GMLFeatureCollection
,IndexedFeatureResults
,ListFeatureCollection
,MappingFeatureCollection
,MaxFeaturesFeatureCollection
,MaxSimpleFeatureCollection
,MemoryFeatureCollection
,PagingFeatureCollection
,PreGeneralizedFeatureCollection
,ProcessingCollection
,ReprojectFeatureResults
,ReprojectingFeatureCollection
,ReTypingFeatureCollection
,SampleDataAccessFeatureCollection
,SimpleProcessingCollection
,SortedSimpleFeatureCollection
,SpatialIndexFeatureCollection
,SubFeatureCollection
,SubFeatureList
,TreeSetFeatureCollection
,WFSContentComplexFeatureCollection
public interface FeatureCollection<T extends FeatureType,F extends Feature>
Collection of features, often handled as a result set.Where possible FeatureCollection is method compatible with
Collection
.SimpleFeatureCollection house rules:
- Each iterator is considered a live connection which must be closed (see example below)
- Features are not specifically ordered within the SimpleFeatureCollection
- Two Feature instances cannot exist with the same
FeatureId
FeatureIterator close
FeatureCollection provides streaming access with the following restriction on the use of
FeatureIterator
: You must callFeatureIterator.close()
. This allows FeatureCollection to clean up any operating system resources used to access information.Example (safe) use:
And in Java 7:FeatureIterator iterator = featureCollection.features(); try { while( iterator.hasNext() ){ Feature feature = iterator.next(); System.out.println( feature.getID() ); } } finally { iterator.close(); }
try ( FeatureIterator iterator = featureCollection.features() ){ while( iterator.hasNext() ){ Feature feature = iterator.next(); System.out.println( feature.getID() ); } }
Handy Tip: Although many resource backed collections will choose to release resources at when the iterator has reached the end of its contents this is not something you should rely on.
FeatureCollection Implementation Tips
Auto close: Try and close up resources when you can detect that an Iterator is no longer in use.
Lazy Connect: FeatureCollection is used in two fashions, as a result set, where each iterator acts as a cursor over the content. Also as a predefined query which can be refined further. An example is using featureCollection.subCollection( Filter ) or featureCollection.sort( SortBy ) before listing features out of a FeatureCollection.
- Author:
- Ian Turton, CCG, Rob Hranac, VFNY, Ian Schneider, USDA-ARS, Jody Garnett, LISAsoft
- See Also:
org.geotools.Feature
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
accepts(FeatureVisitor visitor, ProgressListener progress)
Visit the contents of a feature collection.boolean
contains(Object o)
boolean
containsAll(Collection<?> o)
FeatureIterator<F>
features()
Obtain a FeatureIteratorof the Features within this FeatureCollection. ReferencedEnvelope
getBounds()
Get the total bounds of this collection which is calculated by doing a union of the bounds of each feature inside of itString
getID()
ID used when serializing to GMLT
getSchema()
The schema for the child feature members of this collection.boolean
isEmpty()
Returns true if this feature collection contains no features.int
size()
Please note this operation may be expensive when working with remote content.FeatureCollection<T,F>
sort(SortBy order)
Obtained sorted contents.FeatureCollection<T,F>
subCollection(Filter filter)
SimpleFeatureCollection "view" indicated by provided filter.Object[]
toArray()
<O> O[]
toArray(O[] a)
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Method Detail
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features
FeatureIterator<F> features()
Obtain a FeatureIteratorof the Features within this FeatureCollection. The implementation of FeatureIterator must adhere to the rules of fail-fast concurrent modification. In addition (to allow for resource backed collections) the
FeatureIterator.close()
method must be called.Example use:
FeatureIterator
iterator=collection.features(); try { while( iterator.hasNext() ){ Feature feature = iterator.next(); System.out.println( feature.getID() ); } } finally { iterator.close(); } 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.
- Returns:
- A FeatureIterator.
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getSchema
T getSchema()
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.
- Returns:
- FeatureType describing the "common" schema to all child features of this collection
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getID
String getID()
ID used when serializing to GML
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accepts
void accepts(FeatureVisitor visitor, ProgressListener progress) throws IOException
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.
- Parameters:
visitor
- Closure applied to each feature in turn.progress
- Used to report progress, may be used to interrupt the operation- Throws:
IOException
- Since:
- 2.5
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subCollection
FeatureCollection<T,F> subCollection(Filter filter)
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:
The above recommended use is agreement with the Collections API precident of List.subList( start, end ).collection.subCollection( filter ).clear();
The results of subCollection:
- are to be considered unordered
- may be an ordered FeatureList if requested when sortBy is indicated
- Returns:
- SimpleFeatureCollection identified as subset.
- See Also:
FeatureList
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sort
FeatureCollection<T,F> sort(SortBy order)
Obtained sorted contents.This method may not be supported by all implementations, consider the use of FeatureSource.features( Query ).
- Parameters:
order
- Sort order- Returns:
- FeatureCollection sorted in the indicated order
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getBounds
ReferencedEnvelope getBounds()
Get the total bounds of this collection which is calculated by doing a union of the bounds of each feature inside of it- Returns:
- An Envelope containing the total bounds of this collection.
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contains
boolean contains(Object o)
- See Also:
Collection.contains(Object)
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containsAll
boolean containsAll(Collection<?> o)
- See Also:
Collection.containsAll(Collection)
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isEmpty
boolean isEmpty()
Returns true if this feature collection contains no features.- Returns:
- true if this collection contains no features
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size
int size()
Please note this operation may be expensive when working with remote content.- See Also:
Collection.size()
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toArray
Object[] toArray()
- See Also:
Collection.toArray()
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toArray
<O> O[] toArray(O[] a)
- See Also:
Collection.toArray(Object[])
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