/*******************************************************************************
* Copyright (c) 2007 Oracle Corporation.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Oracle - initial API and implementation
*
********************************************************************************/
package org.eclipse.jst.jsf.common.metadata.query;
import java.util.Collections;
import java.util.List;
/**
* Abstract implementation of {@link IResultSet} that developers may subclass.
* Users should assume that the results are only valid at the time of the query. This may change in the future.
* <p><b>Provisional API - subject to change</b></p>
* @param <T>
*/
public abstract class AbstractResultSet<T> implements IResultSet<T> {
private List _results;
private boolean _isClosed = false;
public List<T> getResults() throws MetaDataException {
initIfNecessary();
return _results;
}
public final void close() throws MetaDataException {
doClose();
_isClosed = true;
_results = null;
}
/**
* Overridable method to close resultset. This is called by close()
* @throws MetaDataException
*/
protected void doClose() throws MetaDataException {
//subclasses to provide override
}
public final boolean isClosed() {
return _isClosed;
}
/**
* @return List of results. Null is tolerated.
*/
protected abstract List<T> getInternalResults();
private void initIfNecessary() throws MetaDataException {
if (_isClosed)
throw new MetaDataException("Attempt to access a closed resultset."); //$NON-NLS-1$
if (_results == null) {
List<T> checkNullResults = getInternalResults();
if (checkNullResults == null){
checkNullResults = Collections.EMPTY_LIST;
}
_results = Collections.unmodifiableList(checkNullResults);
}
}
}