Raible Designs

Saturday January 11, 2003

My First Attempt at ConvertUtils My first attempt at using ConvertUtils is turning out to be a painful one - most likely due to my own ignorance. Let's see if you can help me out. I have a Hibernate Bag, which is really a java.util.List on my User object. When I run the User object through XDoclet, I create a UserForm (extends ValidatorForm). The form has an ArrayList on for any instances of List or Set on the object (set through a custom struts_form.xdt template). So I created a ListConverter to convert a List object to an ArrayList. Sounds pretty simple right?! Here's my ListConverter.java:

public class ListConverter implements Converter {
    //~ Instance fields ========================================================

    protected Log log = LogFactory.getLog(ListConverter.class);

    //~ Methods ================================================================

    /**
     * Convert a List to an ArrayList
     *
     * @param type the class type to output
     * @param value the object to convert
     */
    public Object convert(Class type, Object value) {
        if (log.isDebugEnabled()) {
            log.debug("entering 'convert' method");
        }

        // for a null value, return null
        if (value == null) {
            return null;
        } else if (value instanceof Set && (type == Set.class)) {
            return new ArrayList((Set) value);
        } else if (value instanceof List && (type == List.class)) {
            return new ArrayList((List) value);
        } else {
            throw new ConversionException("Could not convert " + value
                                          + " to ArrayList!");
        }
    }
}

When I run BeanUtils.copyProperties(userForm, user), I get:

Could not convert cirrus.hibernate.collections.Bag@e2892b to ArrayList!

On another class, where I am trying to convert a List of Longs, I get:

Could not convert [-1, 1, 30129] to ArrayList!

I'm registering my custom converter in a static block of my BaseManager class. My *Manager classes do all the conversions, so this seems logical:

static {
    ConvertUtils.register(new StringConverter(), String.class);
    ConvertUtils.register(new LongConverter(), Long.class);
    ConvertUtils.register(new ListConverter(), ArrayList.class);
	
    if (log.isDebugEnabled()) {
        log.debug("Converters registered...");
    }
}

Since I'm in a major time crunch, I'll try simply making my getter/setters on my UserForm to be List. I'd like to use ConvertUtils though, so hopefully someone has a solution.

This brings me to a RANT and I think it's my first official one. My last three projects have always started small, and the goal has always been a prototype of functionality. A prototype that turns into a production system. All fricken three of them. All were supposed to take about 3 months to develop initially. The last two projects took at least 6 months. This one has a one month deadline, but the scope is a lot smaller than the previous two. But still, it's always the same scenario - the clients want a prototype, but turn it into a production system. Since it's a prototype, I tend to write "workarounds" for design patterns (see above) that I can't figure out. Is this good? It probably doesn't hurt since no one will ever look at my code - right?! When's the last time you looked at a co-workers code? (The more == the better). And the truth is, as long as it works - it's probably good enough. However, I as a developer, get heartburn when I think about maintaining the system that I created under the impression that it was a prototype. Maybe one of these days I'll figure out all the best practices to creating a robust web application, and then I'll know everything - so I won't have to write workarounds for my lack of knowledge. If you see some pigs flying, you can think to yourself - "Wow, Raible must've figured it all out" ;-) Posted in Java at Jan 11 2003, 04:04:43 PM MST 1 Comment