casting - Passing a class ("Country.class") as an argument in Java

Question

I'm trying to make a method that takes an argument of Country.class, User.class etc, and returns argument.count().

All the possible classes that I would give to this method extend from Model and have the method count().

My code:

private static long <T> countModel(Model<T> clazz)
{
    // there is other important stuff here, which prevents me from
    // simply by-passing the method altogether.

    return clazz.count();
}

Called by:

renderArgs.put("countryCount", countModel(Country.class));

However this just doesn't work at all.

How do I do this, please?

Answer 1

I think you want to do

private long countModel(Class<? extends Model> clazz) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException
{
  Method countMethod =  clazz.getDeclaredMethod("count", null);
  return (Long) countMethod.invoke(null, null);
}

Hopefully something like this would work (my reflection skills are not really that good).