org.geotools.feature.collection
Class AbstractFeatureList

java.lang.Object
  extended byorg.geotools.feature.collection.AbstractResourceCollection
      extended byorg.geotools.feature.collection.AbstractResourceList
          extended byorg.geotools.feature.collection.AbstractFeatureList
All Implemented Interfaces:
java.util.Collection, Feature, FeatureCollection, FeatureList, FeatureResults, java.util.List, ResourceCollection, ResourceList

public abstract class AbstractFeatureList
extends AbstractResourceList
implements FeatureList


Nested Class Summary
 
Nested classes inherited from class org.geotools.feature.Feature
Feature.NULL
 
Field Summary
 
Fields inherited from class org.geotools.feature.collection.AbstractResourceList
modCount
 
Fields inherited from class org.geotools.feature.collection.AbstractResourceCollection
open
 
Constructor Summary
protected AbstractFeatureList(FeatureCollection collection)
          Feature methods will be delegated to provided state
protected AbstractFeatureList(FeatureState state)
          Feature methods will be delegated to provided state
 
Method Summary
 void accepts(FeatureVisitor visitor)
           
 void addListener(CollectionListener listener)
          Adds a listener for collection events.
 void close(FeatureIterator close)
          Clean up any resources assocaited with this iterator in a manner similar to JDO collections.
 FeatureCollection collection()
          Convert this set of results to a FeatureCollection.
 FeatureIterator features()
          Obtain a FeatureIterator of the Features within this collection.
 java.lang.Object getAttribute(int index)
          Gets an attribute by the given zero-based index.
 java.lang.Object getAttribute(java.lang.String xPath)
          Gets an attribute for this feature at the location specified by xPath.
 java.lang.Object[] getAttributes(java.lang.Object[] attributes)
          Copy all the attributes of this Feature into the given array.
 com.vividsolutions.jts.geom.Envelope getBounds()
          Returns the bounding box of this FeatureResults.
 int getCount()
          Returns the number of Features in this FeatureResults.
 com.vividsolutions.jts.geom.Geometry getDefaultGeometry()
          Gets the default geometry for this feature.
 FeatureType getFeatureType()
          Gets a reference to the type of this feature collection.
 java.lang.String getID()
          Gets the unique feature ID for this feature.
 int getNumberOfAttributes()
          Get the number of attributes this feature has.
 FeatureCollection getParent()
          Gets the feature collection this feature is stored in.
 FeatureType getSchema()
          The schema for the child features of this collection.
 FeatureReader reader()
          Provides access to the Features, please note that FeatureReader is a blocking api.
 void removeListener(CollectionListener listener)
          Removes a listener for collection events.
 void setAttribute(int position, java.lang.Object val)
          Sets an attribute by the given zero-based index.
 void setAttribute(java.lang.String xPath, java.lang.Object attribute)
          Sets a single attribute for this feature, passed as a complex object.
 void setDefaultGeometry(com.vividsolutions.jts.geom.Geometry geometry)
          Sets the default geometry for this feature.
 void setParent(FeatureCollection collection)
          Sets the parent collection this feature is stored in, if it is not already set.
 FeatureList sort(SortBy order)
          collection.subCollection( myFilter ).sort( {"foo","bar"} ); collection.subCollection( myFilter ).sort( "bar" ).sort("foo")
 FeatureCollection subCollection(Filter filter)
          FeatureCollection "view" indicated by provided filter.
 FeatureList subList(Filter filter)
          Similar to subCollection, explicitly constructs a ordered List.
 
Methods inherited from class org.geotools.feature.collection.AbstractResourceList
add, add, addAll, clear, closeIterator, equals, get, hashCode, indexOf, lastIndexOf, listIterator, listIterator, openIterator, openIterator, remove, removeRange, set, subList
 
Methods inherited from class org.geotools.feature.collection.AbstractResourceCollection
addAll, close, contains, containsAll, isEmpty, iterator, purge, remove, removeAll, retainAll, size, toArray, toArray, toString
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface java.util.List
add, add, addAll, addAll, clear, contains, containsAll, equals, get, hashCode, indexOf, isEmpty, iterator, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, retainAll, set, size, subList, toArray, toArray
 
Methods inherited from interface org.geotools.feature.FeatureCollection
accepts, close
 
Methods inherited from interface org.geotools.data.collection.ResourceCollection
iterator, purge
 

Constructor Detail

AbstractFeatureList

protected AbstractFeatureList(FeatureState state)
Feature methods will be delegated to provided state


AbstractFeatureList

protected AbstractFeatureList(FeatureCollection collection)
Feature methods will be delegated to provided state

Method Detail

getParent

public FeatureCollection getParent()
Description copied from interface: Feature
Gets the feature collection this feature is stored in.

Specified by:
getParent in interface Feature
Returns:
The collection that is the parent of this feature.

setParent

public void setParent(FeatureCollection collection)
Description copied from interface: Feature
Sets the parent collection this feature is stored in, if it is not already set. If it is set then this method does nothing.

Specified by:
setParent in interface Feature
Parameters:
collection - the collection to be set as parent.

getFeatureType

public FeatureType getFeatureType()
Description copied from interface: FeatureCollection
Gets a reference to the type of this feature collection.

There are several limitations on the use of FeatureType with respect to a FeatureCollection.

GML 3.x: all FeatureCollections decend from gml:AbstractFeatureCollectionType:

The contents defined in this manner is returned the collection iterator() method.

GML 3.x: gml:AbstractFeatureCollectionType decends from gml:BoundedFeatureType:

The value of the boundedBy attribute should be derived from the contents of the collection.

Implementation Notes

There is a difference between getFeatureType() and getSchema(), getSchema is named for historical reasons and reprensets the LCD FeatureType that best represents the contents of this collection.

Specified by:
getFeatureType in interface FeatureCollection
Returns:
A reference to this collections type

getID

public java.lang.String getID()
Description copied from interface: Feature
Gets the unique feature ID for this feature.

Specified by:
getID in interface Feature
Returns:
Unique identifier for this feature.

getAttributes

public java.lang.Object[] getAttributes(java.lang.Object[] attributes)
Description copied from interface: Feature
Copy all the attributes of this Feature into the given array. If the argument array is null, a new one will be created. Gets all attributes from this feature, returned as a complex object array. This array comes with no metadata, so to interpret this collection the caller class should ask for the schema as well. This array may have multiple entries for each AttributeType depending on the AttributeType's multiplicity.

Specified by:
getAttributes in interface Feature
Parameters:
attributes - An array to copy attributes into. May be null.
Returns:
The array passed in, or a new one if null.

getAttribute

public java.lang.Object getAttribute(java.lang.String xPath)
Description copied from interface: Feature
Gets an attribute for this feature at the location specified by xPath. Due to the complex nature of xpath, a List of all valid values will be returned when an attribute is requested. These values can range from complete Feature Collections to single primative attribute values. When a particular instance of the Attribute is requested, then the Object will be returned. Simply put, in the general case we are assuming the existance of multiplicity, so specify which instance you want or you get them all. Example of getting a list: ./road returns the List of road attribute instances Example of getting an Object: ./road[0] returns the first road

Specified by:
getAttribute in interface Feature
Parameters:
xPath - XPath representation of attribute location.
Returns:
A List of copies of the requested attribute, null if the requested xpath is not found, or NULL_ATTRIBUTE.

getAttribute

public java.lang.Object getAttribute(int index)
Description copied from interface: Feature
Gets an attribute by the given zero-based index. This index is based on the values within the Feature as opposed to the AttributeType declaration. To get the values for the 5th attributeType, use the schema to determine the xPath and class the getAttribute(xPath) method.

Specified by:
getAttribute in interface Feature
Parameters:
index - The requested index. Must be 0 <= idx < getNumberOfAttributes().
Returns:
A copy of the requested attribute, or NULL_ATTRIBUTE.
See Also:
Feature.getAttribute(String)

setAttribute

public void setAttribute(int position,
                         java.lang.Object val)
                  throws IllegalAttributeException,
                         java.lang.ArrayIndexOutOfBoundsException
Description copied from interface: Feature
Sets an attribute by the given zero-based index. This index is based on the values within the Feature as opposed to the AttributeType declaration. To get the values for the 5th attributeType, use the schema to determine the xPath and class the setAttribute(xPath,val) method.

Specified by:
setAttribute in interface Feature
Parameters:
position - The requested index. Must be 0 <= idx < getNumberOfAttributes()
val - An object representing the attribute being set
Throws:
java.lang.ArrayIndexOutOfBoundsException - if an invalid position is given
IllegalAttributeException - if the passed in val does not validate against the AttributeType at that position.
See Also:
Feature.setAttribute(String, Object)

getNumberOfAttributes

public int getNumberOfAttributes()
Description copied from interface: Feature
Get the number of attributes this feature has. This is NOT simply a convenience method for calling getFeatureType().getNumberOfAttributes(). This is the same as calling getAttributes(null).length. This represents the number of actual attribute values in the feature, and may differ from the number of AttributeTypes defined in the FeatureType based on the multiplicity of the AttributeTypes.

Specified by:
getNumberOfAttributes in interface Feature
Returns:
The total number of attributes this Feature contains.

setAttribute

public void setAttribute(java.lang.String xPath,
                         java.lang.Object attribute)
                  throws IllegalAttributeException
Description copied from interface: Feature
Sets a single attribute for this feature, passed as a complex object. If the attribute does not exist or the object does not conform to the internal schema, an exception is thrown. Checking this is, of course, left to the feature to do internally. Well behaved features should always fully check the passed attributes against thire schema before adding them. NOTE: The xPath may contain instance information about multiplicity, for example: ./road[3] which is the third road attribute in this feature.

Specified by:
setAttribute in interface Feature
Parameters:
xPath - XPath representation of attribute location.
attribute - Feature attribute to set.
Throws:
IllegalAttributeException - If the attribute is illegal for the path specified.

getDefaultGeometry

public com.vividsolutions.jts.geom.Geometry getDefaultGeometry()
Description copied from interface: Feature
Gets the default geometry for this feature.

This method will return null if no DefaultGeometry has been defined by the schema.

Specified by:
getDefaultGeometry in interface Feature
Returns:
Default geometry for this feature, or null

setDefaultGeometry

public void setDefaultGeometry(com.vividsolutions.jts.geom.Geometry geometry)
                        throws IllegalAttributeException
Description copied from interface: Feature
Sets the default geometry for this feature.

Specified by:
setDefaultGeometry in interface Feature
Parameters:
geometry - The geometry to set.
Throws:
IllegalAttributeException - If the AttributeType is not a geometry, or is invalid for some other reason.

getBounds

public com.vividsolutions.jts.geom.Envelope getBounds()
Description copied from interface: FeatureResults
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;  
 }
 
 

Specified by:
getBounds in interface FeatureResults
Returns:
Bounding box of this FeatureResults, or an empty Envelope

addListener

public void addListener(CollectionListener listener)
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
Parameters:
listener - The listener to add

removeListener

public void removeListener(CollectionListener listener)
                    throws java.lang.NullPointerException
Description copied from interface: FeatureCollection
Removes a listener for collection events.

Specified by:
removeListener in interface FeatureCollection
Parameters:
listener - The listener to remove
Throws:
java.lang.NullPointerException - If the listener is null.

features

public FeatureIterator 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:

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 FeatureCollection
Returns:
A FeatureIterator.

close

public void close(FeatureIterator close)
Description copied from interface: FeatureCollection
Clean up any resources assocaited with this iterator in a manner similar to JDO collections.

You must be sure to allow null values, this is because in a try/finally block client code may not be sure if they have actualy succeed in assign a value to an iterator they wish to ensure is closed. By permiting null as an api we prevent a null check in lots of finally statements.

Note: Because of FeatureReader using an interator internally, there is only one implementation of this method that makes any sense:


 public void close( FeatureIterator iterator) {
     if( iterator != null ) iterator.close();
 }
 

Specified by:
close in interface FeatureCollection

getSchema

public FeatureType getSchema()
Description copied from interface: FeatureCollection
The schema for the child features of this collection.

There is a difference between getFeatureType() and getSchema()represents the LCD FeatureType that best represents the contents of this collection.

The method getSchema() is named for compatability with the geotools 2.0 API. In the Geotools 2.2 time frame we should be able to replace this method with a careful check of getFeatureType() and its attributes.

Specified by:
getSchema in interface FeatureCollection
Returns:
FeatureType describing the "common" schema to all child features of this collection

accepts

public void accepts(FeatureVisitor visitor)
             throws java.io.IOException
Throws:
java.io.IOException

subList

public FeatureList subList(Filter filter)
Description copied from interface: FeatureList
Similar to subCollection, explicitly constructs a ordered List.

The list will be ordered:

Specified by:
subList in interface FeatureList
Parameters:
filter -
Returns:
FeatureList based on features selected by filter

subCollection

public FeatureCollection subCollection(Filter filter)
Description copied from interface: FeatureCollection
FeatureCollection "view" indicated by provided filter.

The contents of the returned FeatureCollection are determined by applying the provider Fitler 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 FeatureCollection construct. The FeatureCollections returned really should be considered as a temporary "view" used to control the range of a removeAll, or modify opperation.

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:

Specified by:
subCollection in interface FeatureCollection
Parameters:
filter -
Returns:
FeatureCollection identified as subset.
See Also:
FeatureList

sort

public FeatureList sort(SortBy order)
Description copied from interface: FeatureCollection
collection.subCollection( myFilter ).sort( {"foo","bar"} ); collection.subCollection( myFilter ).sort( "bar" ).sort("foo")

Specified by:
sort in interface FeatureCollection
Parameters:
order -
Returns:

reader

public FeatureReader reader()
                     throws java.io.IOException
Description copied from interface: FeatureResults
Provides access to the Features, please note that FeatureReader is a blocking api.

Specified by:
reader in interface FeatureResults
Returns:
A FeatureReader streaming over the FeatureResults
Throws:
java.io.IOException - DOCUMENT ME!

getCount

public int getCount()
             throws java.io.IOException
Description copied from interface: FeatureResults
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;  
 }
 
 

Specified by:
getCount in interface FeatureResults
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
Description copied from interface: FeatureResults
Convert this set of results to a FeatureCollection.

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;  
 }
 

Specified by:
collection in interface FeatureResults
Returns:
DOCUMENT ME!
Throws:
java.io.IOException - If any problems occur aquiring Features


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