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Free Java Reporting Library
/*
* JasperReports - Free Java Reporting Library.
* Copyright (C) 2001 - 2019 TIBCO Software 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.cache;
import java.io.ObjectStreamException;
import java.io.Serializable;
import net.sf.jasperreports.engine.JRConstants;
/**
* @author Lucian Chirita ([email protected])
*/
public class EmptyColumnValues implements ColumnValues, Serializable
{
private static final long serialVersionUID = JRConstants.SERIAL_VERSION_UID;
private static final EmptyColumnValues INSTANCE = new EmptyColumnValues();
public static EmptyColumnValues instance()
{
return INSTANCE;
}
private Object readResolve() throws ObjectStreamException
{
return INSTANCE;
}
@Override
public int size()
{
return 0;
}
@Override
public ColumnValuesIterator iterator()
{
return EmptyColumnValuesIterator.instance();
}
}
class EmptyColumnValuesIterator implements ColumnValuesIterator
{
private static final EmptyColumnValuesIterator INSTANCE = new EmptyColumnValuesIterator();
public static ColumnValuesIterator instance()
{
return INSTANCE;
}
@Override
public void moveFirst()
{
// NOP
}
@Override
public boolean next()
{
return false;
}
@Override
public Object get()
{
throw new IllegalStateException();
}
}