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POWhy can't I define a static method in a Java interface?
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  1. POWhy can't I define a static method in a Java interface?
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    copied!<p>Here's the example:</p> <pre><code>public interface IXMLizable&lt;T&gt; { static T newInstanceFromXML(Element e); Element toXMLElement(); } </code></pre> <p>Of course this won't work. But why not?</p> <p>One of the possible issues would be, what happens when you call:</p> <pre><code>IXMLizable.newInstanceFromXML(e); </code></pre> <p>In this case, I think it should just call an empty method (i.e. {}). All subclasses would be forced to implement the static method, so they'd all be fine when calling the static method. So why isn't this possible?</p> <p><strong>EDIT:</strong> I guess I'm looking for answer that's deeper than "because that's the way Java is". </p> <p>Is there a particular technological reason why static methods can't be overwritten? That is, why did the designers of Java decide to make instance methods overrideable but not static methods?</p> <p><strong>EDIT:</strong> The problem with my design is I'm trying to use interfaces to enforce a coding convention.</p> <p>That is, the goal of the interface is twofold:</p> <ol> <li><p>I want the IXMLizable interface to allow me to convert classes that implement it to XML elements (using polymorphism, works fine).</p></li> <li><p>If someone wants to make a new instance of a class that implements the IXMLizable interface, they will always know that there will be a newInstanceFromXML(Element e) static constructor.</p></li> </ol> <p>Is there any other way to ensure this, other than just putting a comment in the interface?</p> <p><strong>EDIT:</strong> <em>As of Java 8, static methods are now allowed in interfaces.</em></p>
 

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