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    <p>You shouldn't need subclasses that takes <code>LinkedList&lt;UserProfile&gt;</code> and <code>ArrayList&lt;UserProfile&gt;</code> to begin with. Working with <code>List&lt;UserProfile&gt;</code> is more than fine, it's recommended (see <em>Effective Java 2nd Edition, Item 52: Refer to objects by their interfaces</em>).</p> <p>Do keep in mind that <code>LinkedList&lt;E&gt; implements List&lt;E&gt;</code>, and <code>ArrayList&lt;E&gt; implements List&lt;E&gt;</code>, so if you take a <code>List&lt;E&gt;</code>, you can take both <code>LinkedList&lt;E&gt;</code> and <code>ArrayList&lt;E&gt;</code> already (and all other implementors of <code>List&lt;E&gt;</code> out there).</p> <hr> <h3>Regarding <code>clone()</code></h3> <p>It's well understood now that <code>clone()</code> is deeply broken in Java, and should not be used (see <em>Effective Java 2nd Edition, Item 11: Override clone judiciously</em>).</p> <p>From <a href="http://www.artima.com/intv/bloch13.html" rel="nofollow noreferrer">an interview with author Josh Bloch</a>:</p> <blockquote> <p>If you've read the item about cloning in my book, especially if you read between the lines, you will know that I think <code>clone</code> is deeply broken [...] There are very few things for which I use <code>Cloneable</code> anymore [...] It's a shame that <code>Cloneable</code> is broken, but it happens.</p> </blockquote> <h3>Related questions</h3> <ul> <li><a href="https://stackoverflow.com/questions/665860/deep-clone-utility-recomendation">Deep clone utility recomendation recomendation</a></li> <li><a href="https://stackoverflow.com/questions/715650/java-how-to-clone-arraylist-but-also-clone-its-items">Java: how to clone ArrayList but also clone its items?</a></li> <li><a href="https://stackoverflow.com/questions/2597965/why-people-are-so-afraid-of-using-clone-on-collection-and-jdk-classes">Why people are so afraid of using clone() (on collection and JDK classes) ?</a></li> <li><a href="https://stackoverflow.com/questions/2326758/how-to-properly-override-clone-method">How to properly override clone method?</a></li> <li><a href="https://stackoverflow.com/questions/1106102/clone-vs-copy-constructor-vs-factory-method">clone() vs copy constructor vs factory method??</a></li> </ul>
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    1. COSo, you're saying that if I pass a `LinkedList<>` or a `ArrayList<>` into `DBList` constructor (if the constructor takes `List<>` as argument) is enough to differentiate them? It's because they are basically the same, just the internal memory implementation is different?
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    2. CO@Nazgulled: why do you need to distinguish them? Is it not sufficient to just work on a `List<E>`, regardless of the implementation?
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    3. COI'll also need to do something similar but for `Map<K,V>` and then have a `TreeMap<K,V>` and a `HashMap<K,V>`. Should I just use `Map<K,V>` in this situation?
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