NullCondition.java :  » Workflow-Engines » osbl-1_0 » org » concern » library » generic » Java Open Source

package org.concern.library.generic;

import org.concern.controller.AbstractCondition;
import org.concern.controller.ConditionEvaluationException;
import ognl.Ognl;
import ognl.OgnlException;

/**
 * @author hengels
 * @version $Revision$
 */
public class NullCondition
    extends AbstractCondition
{
    String expression;

    public String getExpression() {
        return expression;
    }

    public void setExpression(String expression) {
        this.expression = expression;
    }

    public boolean eval(Object subject) throws ConditionEvaluationException {
        try {
            Object result = Ognl.getValue(expression, subject);
            return result == null;
        }
        catch (OgnlException e) {
            throw new ConditionEvaluationException(e.getMessage());
        }
    }
}