mdbtools.dbengine.functions.Sum Maven / Gradle / Ivy
/*
* #%L
* Fork of MDB Tools (Java port).
* %%
* Copyright (C) 2008 - 2016 Open Microscopy Environment:
* - Board of Regents of the University of Wisconsin-Madison
* - Glencoe Software, Inc.
* - University of Dundee
* %%
* This program 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 2.1 of the
* License, or (at your option) any later version.
*
* This program 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 General Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
package mdbtools.dbengine.functions;
import java.sql.SQLException;
public class Sum implements Aggregate
{
private int sum = -1;
public void execute(Object column)
throws SQLException
{
if (column != null)
{
if (column instanceof Integer == false)
throw new RuntimeException("sum can only operate on integers");
int value = ((Integer)column).intValue();
if (sum == -1)
sum = value;
else
sum += value;
}
}
public Object getResult()
{
int result = sum;
sum = -1;
if (result == -1)
return null;
return new Integer(result);
}
}