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Free Java Reporting Library
/*
* JasperReports - Free Java Reporting Library.
* Copyright (C) 2001 - 2023 Cloud Software Group, Inc. All rights reserved.
* http://www.jaspersoft.com
*
* Unless you have purchased a commercial license agreement from Jaspersoft,
* the following license terms apply:
*
* This program is part of JasperReports.
*
* JasperReports 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, either version 3 of the License, or
* (at your option) any later version.
*
* JasperReports 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.
*
* You should have received a copy of the GNU Lesser General Public License
* along with JasperReports. If not, see .
*/
package net.sf.jasperreports.data;
import java.util.List;
import java.util.ListIterator;
import net.sf.jasperreports.engine.JRDataSource;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JRField;
import net.sf.jasperreports.engine.JRRuntimeException;
/**
* @author Lucian Chirita ([email protected])
*/
public class DataSourceCollection> implements JRDataSource
{
public static final String EXCEPTION_MESSAGE_KEY_METHOD_CALL_ERROR = "data.source.collection.method.call.error";
protected final boolean empty;
protected final ListIterator providerIterator;
protected D currentDataSource;
public DataSourceCollection(List dataSourceProviders) throws JRException
{
this.empty = dataSourceProviders.isEmpty();
this.providerIterator = dataSourceProviders.listIterator();
start();
}
protected final void start() throws JRException
{
if (providerIterator.hasNext())
{
DataSourceProvider provider = providerIterator.next();
this.currentDataSource = provider.getDataSource();
}
}
public D currentDataSource()
{
return currentDataSource;
}
@Override
public boolean next() throws JRException
{
if (empty)
{
return false;
}
if (currentDataSource != null && currentDataSource.next())
{
return true;
}
// go to the next data source that has records
while (providerIterator.hasNext())
{
DataSourceProvider provider = providerIterator.next();
currentDataSource = provider.getDataSource();
if (currentDataSource != null && currentDataSource.next())
{
return true;
}
}
return false;
}
@Override
public Object getFieldValue(JRField field) throws JRException
{
if (currentDataSource == null)
{
// should not happen
throw
new JRRuntimeException(
EXCEPTION_MESSAGE_KEY_METHOD_CALL_ERROR,
(Object[])null);
}
return currentDataSource.getFieldValue(field);
}
}