UUID Converter For Vaadin

Here is a class to convert a java.util.UUID object to String for use in Vaadin. Originally written by a team member at Vaadin, I modified their source code to output lowercase hexadecimal characters as required by the UUID spec.

I filed a feature request ticket with Vaadin to bundle such a class with Vaadin.

Source code…

import com.vaadin.data.util.converter.Converter;
import java.util.Locale;
import java.util.UUID;

/**
 * Modified by Basil Bourque to ensure output of hex string is in lowercase as required by the UUID spec. 2014-08.
 *
 * @author petter@vaadin.com
 */
public class UUIDToStringConverter implements Converter<String , UUID>
{
    private static final String NULL_STRING = "(none)";

    @Override
    public UUID convertToModel ( String value , Class<? extends UUID> targetType , Locale locale ) throws ConversionException
    {
        try {
            return value == null || value.isEmpty() || value.equals( NULL_STRING ) ? null : UUID.fromString( value );
        } catch ( IllegalArgumentException ex ) {
            throw new ConversionException( ex );
        }
    }

    @Override
    public String convertToPresentation ( UUID value , Class<? extends String> targetType , Locale locale ) throws ConversionException
    {
        return value == null ? NULL_STRING : value.toString().toLowerCase(); // The UUID spec *requires* hex-string output to be lowercase. Must tolerate uppercase for input.
    }

    @Override
    public Class<UUID> getModelType ()
    {
        return UUID.class;
    }

    @Override
    public Class<String> getPresentationType ()
    {
        return String.class;
    }
}

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