org.geotools.data
Interface FeatureResults

All Known Implementing Classes:

DefaultFeatureResults

public interface FeatureResults

Highlevel API for Features from a specific Query.

The can opperate as as a kind of Prepaired Query. It is a Query that knows enough information to be rerun. We may wish to rename this class as QueryResults.

Differences from FeatureCollection:

• This API opperates as a source of FeatureReaders (rather than a source of iterators)
• As a Prepaired Query thise class allows other "results" to be asked against the same query. getBounds() is the most logical example, but we may be able to think of others. In Candidate "results" should all be reproduceable by streaming over the generated FeatureReader.

Ideas:

• Chris had the idea of a collection() method that would construct a FeatureCollection (by iterating through the FeartureReader once). This would be a nice transition piece to allow us to test against existing renderers. (we could add the method in deprecated form until the Renderers adapt to the new API).
• Ian had the idea of asynchronous error handling as provided by a High-Level version of FeatureReader. This class might be the place for such work? Something similar to jdbc getWarnings()?
• The idea of forcing a CoordinateSystem is also looking for a home, this may be the place for such work (although I recomend proving a a "hint" in the Query interface).

Version:

$Id: FeatureResults.java,v 1.4 2003/11/13 17:56:33 jive Exp $

Author:

Jody Garnett, Ray Gallagher, Rob Hranac, TOPP, Chris Holmes, TOPP

Method Summary

FeatureCollection	collection() Provides a stop-gap bridge to our existing Renderers.
com.vividsolutions.jts.geom.Envelope	getBounds() Returns the bounding box of this FeatureResults.
int	getCount() Returns the number of Features in this FeatureResults.
FeatureType	getSchema() Returns the FeatureType of this FeatureResuls.
FeatureReader	reader() Provides access to the Features, please note that FeatureReader is a blocking api.

Method Detail

getSchema

public FeatureType getSchema()
                      throws java.io.IOException

Returns the FeatureType of this FeatureResuls.

Returns:

A FeatureType for

Throws:

java.io.IOException - if their is a problem getting the FeatureType.

reader

public FeatureReader reader()
                     throws java.io.IOException

Provides access to the Features, please note that FeatureReader is a blocking api.

Returns:

A FeatureReader streaming over the FeatureResults

Throws:

java.io.IOException

getBounds

public com.vividsolutions.jts.geom.Envelope getBounds()
                                               throws java.io.IOException

Returns the bounding box of this FeatureResults.

This opperation may be expensive. Consider FeatureSource.getBounds( Query ) as an alternative.

This method is logically the same as:

 
 public Envelope getBounds() throws IOException {
     Envelope newBBox = new Envelope();
     Envelope internal;
     Feature feature;
 
     for (FeatureReader r = reader(); r.hasNext();) {
         feature = r.next();
         internal = feature.getDefaultGeometry().getEnvelopeInternal();
         newBBox.expandToInclude(internal);
     }
     return newBBox;  
 }
 
 

Returns:

Bounding box of this FeatureResults

Throws:

java.io.IOException

getCount

public int getCount()
             throws java.io.IOException

Returns the number of Features in this FeatureResults.

This opperation may be expensive. Consider FeatureSource.getCount( Query ) as an alternative.

This method is logically the same as:

 
 public int getCount() throws IOException {
     int count = 0;
     for (FeatureReader r = reader(); r.hasNext(); count++) {
         r.next();
     }
     return count;  
 }
 
 

Returns:

The number of Features in this FeatureResults.

Throws:

java.io.IOException - If there are problems getting the count

collection

public FeatureCollection collection()
                             throws java.io.IOException

Provides a stop-gap bridge to our existing Renderers.

This method is logically the same as:

 
 public FeatureCollection collection() throws IOException {
     FeatureCollection collection = FeatureCollections.newCollection()
     for (FeatureReader r = reader(); r.hasNext();) {
         collection.add( r.next() );
     }
     return collection;  
 }
 
 

Returns:

An In-Memory FeatureCollection for existing Renderers

Throws:

java.io.IOException - If any problems occur aquiring Features