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POCreating a hashCode() Method - Java
 

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    <p>I'm having some trouble writing a <code>hashCode()</code> method for a class I created. This class is meant to be used inside a TreeSet, and as such, it implements Comparable. The class has the following variables:</p> <pre><code>public class Node implements Comparable&lt;Node&gt; { Matrix matrix; int[] coordinates= new int[2]; Node father; int depth; int cost; </code></pre> <p>Here's the implementation of the <code>compareTo()</code> method. I want the <code>TreeSet</code> to organize these Node structures by their cost, therefore, <code>compareTo()</code> returns the result of a simple subtraction.</p> <pre><code>public int compareTo(Node nodeToCompare) { return this.cost - nodeToCompare.cost; } </code></pre> <p>I also implemented an <code>equals()</code> method.</p> <pre><code>public boolean equals(Object objectToCompare) { if(objectToCompare== this) {return true;} if(objectToCompare== null || objectToCompare.getClass()!= this.getClass()) {return false;} Node objectNode= (Node) objectToCompare; return this.father.equals(objectNode.father) &amp;&amp; this.depth== objectNode.depth &amp;&amp; this.cost== objectNode.cost &amp;&amp; this.matrix.equals(objectNode.matrix) &amp;&amp; Arrays.equals(this.coordinates, objectNode.coordinates); } </code></pre> <p>Having said all of that, I have a few questions:</p> <ol> <li>Since I implemented a new <code>equals()</code> method, should I implement a new <code>hashCode()</code> method?</li> <li>How can I go about implementing a new hashCode <code>method()</code> with those variables? (Note that the variable matrix of the type Matrix has a <code>hashCode()</code> method implemented)</li> </ol> <p>That's all!</p>
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