public ClassAttributeValueExp() 
{
        /* Compatibility: we have an attr field that we must hold on to
           for serial compatibility, even though our parent has one too.  */
        super("Class");
        attr = "Class";
}

Basic Constructor.

 public ValueExp apply(ObjectName name) throws InvalidApplicationException, BadBinaryOpValueExpException, BadStringOperationException, BadAttributeValueExpException 
{
        // getAttribute(name);
        Object result = getValue(name);
        if  (result instanceof String) {
            return new StringValueExp((String)result);
        } else {
            throw new BadAttributeValueExpException(result);
        }
}

Applies the ClassAttributeValueExp on an MBean. Returns the name of the Java implementation class of the MBean.

 protected Object getValue(ObjectName name) 
{
        try {
            // Get the class of the object
            MBeanServer server = QueryEval.getMBeanServer();
            return server.getObjectInstance(name).getClassName();
        } catch (Exception re) {
            return null;
            /* In principle the MBean does exist because otherwise we
               wouldn't be evaluating the query on it.  But it could
               potentially have disappeared in between the time we
               discovered it and the time the query is evaluated.
               Also, the exception could be a SecurityException.
               Returning null from here will cause
               BadAttributeValueExpException, which will in turn cause
               this MBean to be omitted from the query result.  */
        }
}

 public String toString() 
{
        return attr;
}

Returns the string "Class" representing its value