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POBeginner: Trying to have a class with an interface extend another class
 

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    <p>I have two classes, and I would like for my second class to acces private data from the first class.</p> <p>Normally I'd have:</p> <pre><code>public class GenericDictionary&lt;T&gt; implements GenericDictionary_interface&lt;T&gt; { public class Iterator&lt;T&gt; extends GenericDictionary&lt;T&gt; { </code></pre> <p>But I have an interface, I don't EXACTLY know how they work, sometimes they seem to not be necessary.</p> <pre><code>public class Iterator&lt;T&gt; implements Iterator_interface&lt;T&gt; { </code></pre> <p>How can I extend another class and have an interface ? Is the interface not needed ? should the interface of my <code>Iterator&lt;T&gt;</code> class be in the supper's interface ? If so ... how ?</p> <p><strong>P.S.</strong> please don't lecture me on why I'm doing what I'm doing (aka making my own stuff instead of using the ones in java.util.*)</p> <p><strong>EDIT:</strong> Even though I decided to go with inner classes, the answer to my question is the order of extends and implements, thank you.</p>
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    1. COAs I have already told you in your previous question: Iterator should NOT extend GenericDictionary. There is no *is-a* association between both. You're abusing inheritance. If you want to access private members of your dictionary from your iterator, implement it as an inner class, as the standard JDK classes do.
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    2. CO@JBNizet And as I probably already mentioned ... I have no idea how. The JDK is just too dense for me. Your comment is of little help. I understand this is maybe not OK, however I need, for example: `.capacity()`. I cannot procede without it. Since my first class already exists ... my only other option is to pass it as a parameter, but that just seems non-intuitive or at the very least: wrong.
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      1. USKalec
    3. CODo you know what inner classes are? If not, google for "Java tutorial inner class", and you'll find a tutorial. As I told you already: highlight HashMap in your IDE and choose "View Source". Then go to the `iterator()` method definition, and you'll find an example implementation. Passing the dictionary as a parameter to the constructor of your iterator is a much much better solution than yours, and is in fact what an inner class implicitely does. So you could do that if you don't want to use an inner class.
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