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POHelp with abstract class in Java with private variable of type List<E>
 

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  1. POHelp with abstract class in Java with private variable of type List<E>
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    <p>It's been two years since I last coded something in Java so my coding skills are bit rusty.</p> <p>I need to save data (an user profile) in different data structures, <code>ArrayList</code> and <code>LinkedList</code>, and they both come from <code>List</code>. I want to avoid code duplication where I can and I also want to follow good Java practices.</p> <p>For that, I'm trying to create an abstract class where the private variables will be of type <code>List&lt;E&gt;</code> and then create 2 sub-classes depending on the type of variable.</p> <p>Thing is, I don't know if I'm doing this correctly, you can take a look at my code:</p> <p><strong>Class: DBList</strong></p> <pre><code>import java.util.List; public abstract class DBList { private List&lt;UserProfile&gt; listName; private List&lt;UserProfile&gt; listSSN; public List&lt;UserProfile&gt; getListName() { return this.listName; } public List&lt;UserProfile&gt; getListSSN() { return this.listSSN; } public void setListName(List&lt;UserProfile&gt; listName) { this.listName = listName; } public void setListSSN(List&lt;UserProfile&gt; listSSN) { this.listSSN = listSSN; } } </code></pre> <p><strong>Class: DBListArray</strong></p> <pre><code>import java.util.ArrayList; public class DBListArray extends DBList { public DBListArray() { super.setListName(new ArrayList&lt;UserProfile&gt;()); super.setListSSN(new ArrayList&lt;UserProfile&gt;()); } public DBListArray(ArrayList&lt;UserProfile&gt; listName, ArrayList&lt;UserProfile&gt; listSSN) { super.setListName(listName); super.setListSSN(listSSN); } public DBListArray(DBListArray dbListArray) { super.setListName(dbListArray.getListName()); super.setListSSN(dbListArray.getListSSN()); } } </code></pre> <p><strong>Class: DBListLinked</strong></p> <pre><code>import java.util.LinkedList; public class DBListLinked extends DBList { public DBListLinked() { super.setListName(new LinkedList&lt;UserProfile&gt;()); super.setListSSN(new LinkedList&lt;UserProfile&gt;()); } public DBListLinked(LinkedList&lt;UserProfile&gt; listName, LinkedList&lt;UserProfile&gt; listSSN) { super.setListName(listName); super.setListSSN(listSSN); } public DBListLinked(DBListLinked dbListLinked) { super.setListName(dbListLinked.getListName()); super.setListSSN(dbListLinked.getListSSN()); } } </code></pre> <p><strong>1)</strong> Does any of this make any sense? What am I doing wrong? Do you have any recommendations?</p> <p><strong>2)</strong> It would make more sense for me to have the constructors in <code>DBList</code> and calling them (with <code>super()</code>) in the subclasses but I can't do that because I can't initialize a variable with <code>new List&lt;E&gt;()</code>.</p> <p><strong>3)</strong> I was thought to do deep copies whenever possible and for that I always override the <code>clone()</code> method of my classes and code it accordingly. But those classes never had any lists, sets or maps on them, they only had strings, ints, floats. How do I do deep copies in this situation?</p>
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