/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2004-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.data.store;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.opengis.feature.simple.SimpleFeature;
/**
* This iterator is used to indicate that contents could not be aquired.
* <p>
* The normal Collection.iterator() method does not let us return an error
* (we always have to return an iterator). However Iterator.next() can
* be used to return an NoSuchElementException.
* </p>
* <p>
* So we are basically going to lie, we are going to pretend their is content
* *once*, and when they ask for it we are going to hit them with
* a NoSuchElementExcetion. This is a mean trick, but it does convey the idea
* of asking for content that is supposed to be there and failing to aquire it.
* </p>
* @author jgarnett
* @since 2.1.RC0
*
*
* @source $URL$
*/
public class NoContentIterator implements Iterator<SimpleFeature> {
Throwable origionalProblem;
public NoContentIterator( Throwable t ){
origionalProblem = t;
}
public boolean hasNext() {
return origionalProblem != null;
}
public SimpleFeature next() {
if( origionalProblem == null ){
// you only get the real error on the first offense
// (after that you are just silly)
//
throw new NoSuchElementException();
}
NoSuchElementException cantFind = new NoSuchElementException( "Could not aquire feature:" + origionalProblem );
cantFind.initCause( origionalProblem );
origionalProblem = null;
throw cantFind;
}
public void remove() {
if( origionalProblem == null ){
// user did not call next first
throw new UnsupportedOperationException();
}
// User did not call next first
throw new IllegalStateException();
}
}