<p>I inherited this gigantic legacy Java web app using Struts 1.2.4. I have a specific question regarding ActionForms. Some of them have only String properties (even for numbers), some of them use the seemingly appropriate types (Integer, Date, String, etc). What's the best practice here?</p>

<p>Also, it seems that if a property is of type Integer, and the value the user entered is not an integer value, Struts silently swallows this and just doesn't set the property. What's up with this?</p>

For Struts 1.2x, properties where the user enters or selects values on the HTML form and that are populated on the ActionForm instance automatically by the Struts HTML tags must be Strings or booleans. However, there's no reason why your ActionForm can't have getter methods that return the properties as more meaningful types for your application e.g. Date.