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    <p>By declaring the method</p> <pre><code>public static Formatter&lt;? extends AbstractItem&gt; create() </code></pre> <p>you are declaring that the caller of this method will never know the exact type of the <code>Formatter</code>; the caller will only know that it is some <code>Formatter&lt;X&gt;</code> where <code>X</code> is <code>AbstractItem</code> or a subclass of it. So you can’t pass any instance to the returned <code>Formatter</code> as you never know which <code>X</code> the formatter can handle.</p> <p>Suppressing the warning here is absolutely wrong, the compiler tells you the right thing: your code is unsafe. Given two subclasses of <code>AbstractItem</code>, <code>Foo</code> and <code>Bar</code> the factory could return a <code>Formatter&lt;Foo&gt;</code> and you could pass an instance of <code>Bar</code> to its <code>format</code> method.</p> <p>There’s the semantic problem that there is no indicator for what <code>Formatter</code> your factory will return and why. Either you make it a concrete factory returning a <code>Formatter&lt;X&gt;</code> where X is a concrete type instead of <code>? extends …</code> or you have to add a parameter to provide a hint to the factory, which kind of formatter is required, e.g.</p> <pre><code>public static &lt;T extends AbstractItem&gt; Formatter&lt;T&gt; create(Class&lt;T&gt; forItemType) </code></pre> <p>Or you turn it into</p> <pre><code>public static Formatter&lt;AbstractItem&gt; create() </code></pre> <p>specifying that the returned <code>Formatter</code> can handle <em>all</em> kinds of <code>AbstractItem</code>. Just remember that you still can pass any subclass of <code>AbstractItem</code> to a <code>Formatter&lt;AbstractItem&gt;</code> as every instance of a subclass of <code>AbstractItem</code> is still an instance of <code>AbstractItem</code> too, just like in the pre-Generics times.</p>
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    1. COThanks, that explanation makes sense.
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    2. COI forgot one other solution: the factory itself could have a type parameter as well so a `Factory<T>` can return a `Formatter<T>`
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