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copied!<p>Unfortunately Christoph's solution as written only works in very limited circumstances. [EDIT: as commented below I no longer remember my reasoning for this sentence and it is likely wrong: "Note that this will only work in abstract classes, first of all."] The next difficulty is that <code>g()</code> only works from DIRECT subclasses of <code>A</code>. We can fix that, though:</p> <pre><code>private Class<?> extractClassFromType(Type t) throws ClassCastException { if (t instanceof Class<?>) { return (Class<?>)t; } return (Class<?>)((ParameterizedType)t).getRawType(); } public Class<B> g() throws ClassCastException { Class<?> superClass = getClass(); // initial value Type superType; do { superType = superClass.getGenericSuperclass(); superClass = extractClassFromType(superType); } while (! (superClass.equals(A.class))); Type actualArg = ((ParameterizedType)superType).getActualTypeArguments()[0]; return (Class<B>)extractClassFromType(actualArg); } </code></pre> <p>This will work in many situations in practice, but not ALL the time. Consider:</p> <pre><code>public class Foo<U,T extends Collection<?>> extends A<T> {} (new Foo<String,List<Object>>() {}).g(); </code></pre> <p>This will throw a <code>ClassCastException</code>, because the type argument here isn't a <code>Class</code> or a <code>ParameterizedType</code> at all; it's the <code>TypeVariable</code> <code>T</code>. So now you would be stuck trying to figure out what type <code>T</code> was supposed to stand for, and so on down the rabbit hole.</p> <p>I think the only reasonable, general answer is something akin to Nicolas's initial answer -- in general, if your class needs to instantiate objects of some other class that is unknown at compile-time, users of your class need to pass that class literal (or, perhaps, a Factory) to your class explicitly and not rely solely on generics.</p>

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