AbstractFeatureCollection (Geotools modules 21.0 API)

Object
- AbstractFeatureCollection

All Implemented Interfaces:

SimpleFeatureCollection, FeatureCollection<SimpleFeatureType,SimpleFeature>

Direct Known Subclasses:

ForceCoordinateSystemFeatureResults, ListFeatureCollection, MemoryFeatureCollection, ReprojectFeatureResults
```
public abstract class AbstractFeatureCollection
extends Object
implements SimpleFeatureCollection
```
Implement a feature collection just based on provision of an Iterator.
This implementation asks you to implement:
- openIterator()
- size()
- User interaction is provided by the public API for FeatureCollection:
  - features(): makes use of DelegateSimpleFeatureIterator (if needed) to wrap your iterator up as a SimpleFeatureIterator for public use.
  This is the origional implementation of FeatureCollection and is recommended when presenting Collection classes as a FeatureCollection.
Author:

Jody Garnett (LISAsoft)

Field Summary

Fields
Modifier and Type Field and Description

protected String id
id used when serialized to gml

protected SimpleFeatureType schema

Fields
Modifier and Type	Field and Description
`protected String`	`id` id used when serialized to gml
`protected SimpleFeatureType`	`schema`

Constructor Summary

Constructors
Modifier Constructor and Description

protected AbstractFeatureCollection(SimpleFeatureType memberType)

Constructors
Modifier	Constructor and Description
`protected`	`AbstractFeatureCollection(SimpleFeatureType memberType)`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`accepts(FeatureVisitor visitor, ProgressListener progress)` Visit the contents of a feature collection.
`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 SimpleFeatureIterator of the Features within this SimpleFeatureCollection.
`abstract ReferencedEnvelope`	`getBounds()` Subclasses need to override this.
`String`	`getID()` ID used when serializing to GML
`SimpleFeatureType`	`getSchema()` The schema for the child feature members of this collection.
`boolean`	`isEmpty()` Returns `true` if this feature collection contains no features.
`Iterator<SimpleFeature>`	`iterator()` Provides acess to `openIterator()` used to traverse collection contents.
`protected abstract Iterator<SimpleFeature>`	`openIterator()` Factory method used to open an iterator over collection contents for use by `iterator()` and `features()`.
`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.
`Object[]`	`toArray()` Array of all the elements.
`<O> O[]`	`toArray(O[] a)`

Methods inherited from class Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - id
```
protected String id
```
    id used when serialized to gml
  - schema
```
protected SimpleFeatureType schema
```
- Constructor Detail
  - AbstractFeatureCollection
```
protected AbstractFeatureCollection(SimpleFeatureType memberType)
```
- Method Detail
  - features
```
public SimpleFeatureIterator features()
```
    Description copied from interface: SimpleFeatureCollection
    Obtain a SimpleFeatureIterator of the Features within this SimpleFeatureCollection.
    The implementation of FeatureIterator must adhere to the rules of fail-fast concurrent modification. In addition (to allow for resource backed collections) the SimpleFeatureIterator.close() method must be called.
    Example use:
```
 SimpleFeatureIterator iterator=collection.features();
 try {
     while( iterator.hasNext()  ){
          SimpleFeature feature = iterator.next();
          System.out.println( feature.getID() );
     }
 }
 finally {
     iterator.close();
 }
 
```
    Specified by:
    
    features in interface SimpleFeatureCollection
    
    Specified by:
    
    features in interface FeatureCollection<SimpleFeatureType,SimpleFeature>
    
    Returns:
    
    A FeatureIterator.
  - openIterator
```
protected abstract Iterator<SimpleFeature> openIterator()
```
    Factory method used to open an iterator over collection contents for use by iterator() and features().
    If you return an instance of FeatureIterator some effort is taken to call the FeatureIterator.close() internally, however we cannot offer any assurance that client code using iterator() will perform the same check.
    
    Returns:
    
    Iterator over collection contents
  - 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()
  - 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)
  - iterator
```
public final Iterator<SimpleFeature> iterator()
```
    Provides acess to openIterator() used to traverse collection contents.
    You are asked to perform the following check when finished with the iterator:
```
 if( e instanceof FeatureIterator ){
    (FeatureIterator)iterator).close();
 }
```
    Returns:
    
    Iterator traversing collection contents
  - isEmpty
```
public boolean isEmpty()
```
    Description copied from interface: FeatureCollection
    
    Returns true if this feature collection contains no features.
    
    Specified by:
    
    isEmpty in interface FeatureCollection<SimpleFeatureType,SimpleFeature>
    
    Returns:
    
    true if this collection contains no elements.
  - 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 <O> O[] toArray(O[] a)
```
    Specified by:
    
    toArray in interface FeatureCollection<SimpleFeatureType,SimpleFeature>
    
    See Also:
    
    Collection.toArray(Object[])
  - accepts
```
public void accepts(FeatureVisitor visitor,
                    ProgressListener progress)
             throws IOException
```
    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
    
    Throws:
    
    IOException
  - 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>
  - 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.

Class AbstractFeatureCollection

Field Summary

Constructor Summary

Method Summary

Methods inherited from class Object

Field Detail

id

schema

Constructor Detail

AbstractFeatureCollection

Method Detail

features

openIterator

size

contains

containsAll

iterator

isEmpty

toArray

toArray

accepts

subCollection

sort

getID

getSchema

getBounds