examples/Vlib/src/net/sf/tapestry/vlib/EntitySelectionModel.java

//
// Tapestry Web Application Framework
// Copyright (c) 2000-2002 by Howard Lewis Ship
//
// Howard Lewis Ship
// http://sf.net/projects/tapestry
// mailto:hship@users.sf.net
//
// This library is free software.
//
// You may 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 should be included with this distribution in
// the file LICENSE, as well as License.html. If the license is not
// included with this distribution, you may find a copy at the FSF web
// site at 'www.gnu.org' or 'www.fsf.org', or you may write to the
// Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139 USA.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied waranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//

package net.sf.tapestry.vlib;

import java.util.ArrayList;
import java.util.List;

import net.sf.tapestry.ApplicationRuntimeException;
import net.sf.tapestry.form.IPropertySelectionModel;

/**
 *  This class is used as a property selection model to select a primary key.
 *  We assume that the primary keys are integers, which makes it easy to
 *  translate between the various representations.
 *
 *  @version $Id$
 *  @author Howard Lewis Ship
 *
 **/

public class EntitySelectionModel implements IPropertySelectionModel
{
    private static class Entry
    {
        Integer primaryKey;
        String label;

        Entry(Integer primaryKey, String label)
        {
            this.primaryKey = primaryKey;
            this.label = label;
        }

    }

    private static final int LIST_SIZE = 20;

    private List entries = new ArrayList(LIST_SIZE);

    public void add(Integer key, String label)
    {
        Entry entry;

        entry = new Entry(key, label);
        entries.add(entry);
    }

    public int getOptionCount()
    {
        return entries.size();
    }

    private Entry get(int index)
    {
        return (Entry) entries.get(index);
    }

    public Object getOption(int index)
    {
        return get(index).primaryKey;
    }

    public String getLabel(int index)
    {
        return get(index).label;
    }

    public String getValue(int index)
    {
        Integer primaryKey;

        primaryKey = get(index).primaryKey;

        if (primaryKey == null)
            return "";

        return primaryKey.toString();
    }

    public Object translateValue(String value)
    {
        if (value.equals(""))
            return null;

        try
        {
            return new Integer(value);
        }
        catch (NumberFormatException e)
        {
            throw new ApplicationRuntimeException("Could not convert '" + value + "' to an Integer.", e);
        }
    }
}