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POHow can I require a generic parameter to be an enum that implements an interface?
 

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  1. POHow can I require a generic parameter to be an enum that implements an interface?
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    <p>I'm not 100% convinced that this is a good idea, but I bumped into some code today that's currently implemented as:</p> <pre><code>class MyWidget &lt;T extends Enum&lt;T&gt; &gt; { MyWidget(Map&lt;T, Integer&gt; valueMap) { mValueMap = valueMap; } Map&lt;T, Integer&gt; mValueMap; } </code></pre> <p>where <code>MyWidget</code> then offers methods that use <code>mValueMap</code> to convert the passed-in <code>Enum</code> to/from an <code>Integer</code>.</p> <p>What I was considering doing was trying to refactor this, so that I'd declare my enumeration:</p> <pre><code>interface MyInterface { public Integer getValue(); } enum MyEnum implements MyInterface { foo, bar; public Integer getValue() { return ordinal(); } } </code></pre> <p>And I'd then be able to rewrite <code>MyWidget</code> into something that looked vaguely like this:</p> <pre><code>public class MyWidget&lt;T extends Enum&lt;T&gt; extends MyInterface&gt; { ... } </code></pre> <p>and would then be able to call the <code>getValue()</code> method from <code>MyInterface</code> on <code>T</code>-type objects within <code>MyWidget</code>. The problem, of course, is that "<code>&lt;T extends Enum&lt;T&gt; extends MyInterface&gt;</code>" isn't valid syntax. Is there any way to pull this off?</p> <p>I don't want to just have <code>MyWidget&lt;T extends MyInterface&gt;</code>, because it's also important that T be an enumeration.</p> <p>Thanks in advance!</p>
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