Package org.geotools.api.data
Interface FeatureReader<T extends FeatureType,F extends Feature>
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- All Superinterfaces:
AutoCloseable
,Closeable
- All Known Subinterfaces:
DelegatingFeatureReader<T,F>
,SimpleFeatureReader
- All Known Implementing Classes:
AssetsMappingReader
,CollectionFeatureReader
,CollectionReader
,CSVFeatureReader
,DefaultFeatureReader
,DelegateFeatureReader
,DelegateSimpleFeatureReader
,DiffFeatureReader
,EmptyFeatureReader
,EmptySimpleFeatureReader
,FCBuffer
,FIDFeatureReader
,FilteringFeatureReader
,FilteringSimpleFeatureReader
,ForceCoordinateSystemFeatureReader
,GeoJSONFeatureReader
,JDBCClosingFeatureReader
,JDBCFeatureReader
,JDBCInsertFeatureWriter
,JDBCJoiningFeatureReader
,JDBCJoiningFilteringFeatureReader
,JDBCUpdateFeatureWriter
,JDBCUpdateInsertFeatureWriter
,MaxFeatureReader
,MemoryFeatureReader
,MongoFeatureReader
,PreGeneralizedFeatureReader
,PropertyFeatureReader
,ReprojectFeatureReader
,ReTypeFeatureReader
,SortedFeatureReader
,VPFFeatureReader
,VPFFileFeatureReader
public interface FeatureReader<T extends FeatureType,F extends Feature> extends Closeable
The low-level interface for reading Features. Will use the underlying AttributeReader and the given FeatureType to create new Features.Typical use is as follows:
FeatureReader reader = null; try{ for( reader = data.getFeatureReader( filter ); reader.hasNext(); ){ f = reader.next(); ... } } catch (IOException problem){ ... } finally { if( reader != null ){ try { reader.close(); } catch( IOException eek){ } } }
Questions and Suggestions
- Q: Should FeatureReader provide access to the AttributeReaders it uses?
A: No, it looks like we will make a lazy Feature in order to cleanly allow for lazy parsing of attribtues. - Q:FeatureReader has a close method, but no open method?
A: This is by design allowing FeatureReader to encapsulate its InputStream or Rowset). Please assume that FeatureReaders are a single use proposition. - Q: All that exception handling is a pain! A: Yes it is, we have constructed semi-normal Java iterators to cut down on the pain. But you *do* still have to close 'em - this is IO after all.
- Q: Can we include skip(int) - SeanG A: The order of the contents is not "known" or predicatable to the end user, so skip( int ) would be useless. For random access (a higher order of abstraction then FeatureReader) please look at FeatureList.
- Author:
- Ian Schneider, Sean Geoghegan, Defence Science and Technology Organisation.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
close()
Release the underlying resources associated with this stream.T
getFeatureType()
Return the FeatureType this reader has been configured to create.boolean
hasNext()
Query whether this FeatureReader has another Feature.F
next()
Reads the next Feature in the FeatureReader.
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Method Detail
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getFeatureType
T getFeatureType()
Return the FeatureType this reader has been configured to create.- Returns:
- the FeatureType of the Features this FeatureReader will create.
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next
F next() throws IOException, IllegalArgumentException, NoSuchElementException
Reads the next Feature in the FeatureReader.- Returns:
- The next feature in the reader.
- Throws:
IOException
- If an error occurs reading the Feature.IllegalAttributeException
- If the attributes read do not comply with the FeatureType.NoSuchElementException
- If there are no more Features in the Reader.IllegalArgumentException
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hasNext
boolean hasNext() throws IOException
Query whether this FeatureReader has another Feature.- Returns:
- True if there are more Features to be read. In other words, true if calls to next would return a feature rather than throwing an exception.
- Throws:
IOException
- If an error occurs determining if there are more Features.
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close
void close() throws IOException
Release the underlying resources associated with this stream.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Throws:
IOException
- if an I/O error occurs
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