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    <p>Java supports covariant return types, so that's one option. Take advantage of the fact that both <code>A</code> and <code>B</code> are derived from <code>Object</code>:</p> <pre><code>public interface I { Object getSelf(); // or I, see below } public class A implements I { A getSelf() { return this; } } public class B implements I { B getSelf() { return this; } } </code></pre> <p>The point is that both <code>A.getSelf()</code> and <code>B.getSelf()</code> are legitimate overrides of <code>I.getSelf()</code>, even though their return type is different. That's because every <code>A</code> can be treated <em>like</em> an <code>Object</code>, and so the return type is <em>compatible</em> with that of the base function. (This is called "covariance".)</p> <p>In fact, since <code>A</code> and <code>B</code> are also known to derive from <code>I</code>, you can replace <code>Object</code> by <code>I</code> for the same reasons.</p> <p>Covariance is generally a Good Thing: Someone who has an interface object of type <code>I</code> can call <code>getSelf()</code> and get another interface, and that's all she needs to know. On the other hand, someone who already knows he has an <code>A</code> object can call <code>getSelf()</code> and will actually get another <code>A</code> object back. The additional information can be used to get a more specific derived type, but someone who lacks that information still gets everything that's prescribed by the interface base class:</p> <pre><code>I x = new A(); A y = new A(); I a = x.foo(); // generic A b = y.foo(); // we have more information, but b also "is-an" I A c = (A)x.foo(); // "cheating" (we know the actual type) </code></pre>
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    1. POHow can I refer to the class type a interface is implementing in Java?
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    1. USKerrek SB
    1. USKerrek SB
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    1. COI think this is the solution I was looking for. Although this does not seems better or clearer to me than using templates, this is an alternative. Thanks!
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      1. USLeonardo Raele
    2. CO@LeonardoRaele - it is exactly the solution that you dismissed when you said *"I cann't use an 'I'"* :-)
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      1. USStephen C
    3. CO@StephenC: Indeed - this isn't as much a "solution" as it is an explanation of why your initial idea is correct: The language was designed with this behaviour in mind!
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