Java Doc for AbstractResourceCollection.java in  » GIS » GeoTools-2.4.1 » org » geotools » feature » collection » Java Source Code / Java DocumentationJava Source Code and Java Documentation

This implementation is a port of java.util.Collection with support for the use of close( Iterator ). This will allow subclasses that make use of resources during iterator() to be uses safely.

Subclasses are reminded that they should construct their Iterator to return system resources once content has been exhuasted. While this class is safe, and we remind users, not all libraries that accept collections can be hacked.

How to Collectionify Resource Access

We need to do the same things as for use of AbstractCollection - namely:

• Read-Only: provide implementations for size and openIterator ( w/ hasNext() and next().) and finally closeIteartor( iterator )

• Modifiable collection Do all of the above and supply add( Object ) let that Iterator do remove()

Why not play with iterator()? Because we are keeping track of them for later purge()...

This implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.
Parameters:
  o - object to be checked for containment in this collection.

Note: If you return a ResourceIterator, the default implemntation of close( Iterator ) will know what to do.

 Iterator iterator = collection.iterator();
 try {
 for( Iterator i=collection.iterator(); i.hasNext();){
 Feature feature = (Feature) i.hasNext();
 System.out.println( feature.getID() );
 }
 }
 finally {
 collection.close( iterator );
 }
 

As an example if the iterator was working off a File then the inputstream should be closed.

Subclass must call super.close( close ) to allow the list of open iterators to be adjusted.

This implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.
Parameters:
  o - object to be checked for containment in this collection. true if this collection contains the specified element.

Parameters:
  c - collection to be checked for containment in this collection. true if this collection contains all of the elementsin the specified collection.
throws:
  NullPointerException - if the specified collection is null.
See Also:   AbstractResourceCollection.contains(Object)

Note: If you return a ResourceIterator, the default implemntation of close( Iterator ) will know what to do.

Please subclass to provide your own iterator for the the ResourceCollection, note iterator() is implemented to call open() and track the results in for later purge(). Iterator based on resource use

This method should be used with great caution, it is however available to allow the use of the ResourceCollection with algorthims that are unaware of the need to close iterators after use.

Example of using a normal Collections utility method:

 Collections.sort( collection );
 collection.purge(); 
 

Parameters:
  c - elements to be removed from this collection. true if this collection changed as a result of thecall.
throws:
  UnsupportedOperationException - if the removeAll methodis not supported by this collection.
throws:
  NullPointerException - if the specified collection is null.
See Also:   AbstractResourceCollection.remove(Object)
See Also:   AbstractResourceCollection.contains(Object)