org.neo4j.graphdb
Interface ResourceIterable<T>

Type Parameters:

T - the type of values returned through the iterators

All Superinterfaces:

Iterable<T>

public interface ResourceIterable<T>
extends Iterable<T>

Iterable whose iterators have associated resources that need to be released. ResourceIterators obtained inside a transaction are always automatically released when the transaction is committed or rolled back. Outside a transaction, you must ensure that all returned ResourceIterators are either fully exhausted, or explicitly closed. Failure to ensure this may cause indefinitely blocking of write operations.

If you intend to exhaust the returned iterators, you can use conventional code as you would with a normal Iterable:

 ResourceIterable<Object> iterable;
 for ( Object item : iterable )
 {
     ...
 }
 

However, if your code might not exhaust the iterator, (run until Iterator.hasNext() returns false), ResourceIterator provides you with a ResourceIterator.close() method that should be invoked to free its resources, by using a finally-block, or try-with-resource.

 ResourceIterable<Object> iterable;
 ResourceIterator<Object> iterator = iterable.iterator();
 try
 {
     while ( iterator.hasNext() )
     {
         Object item = iterator.next();
         if ( ... )
         {
             return item; // iterator may not be exhausted.
         }
     }
 }
 finally
 {
     iterator.close();
 }
 

See Also:

ResourceIterator, Transaction

Method Summary

ResourceIterator<T>

iterator() Returns an iterator with associated resources that must be managed.

Method Detail

iterator

ResourceIterator<T> iterator()

Returns an iterator with associated resources that must be managed. Don't forget to either exhaust the returned iterator or call the close method on it.

Specified by:

iterator in interface Iterable<T>