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POUnderstanding inheritance of class variables
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  1. POUnderstanding inheritance of class variables
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    copied!<p>I'm building a <code>Challenge24Solver</code> class in Java. The logic itself works and finds the solutions as would be expected (with an arbitrary number of arguments). Anyway that part of the projects is works as I expect.</p> <p>The question comes from problems with the representation of the solutions. It's fair to say that I've completed this project in Python and decided to attempt in Java as a sort of introduction, which may be the problem, that I'm trying to do this too like Python.</p> <p>Here are some of my classes:</p> <pre><code>abstract class Operation { \\ Basic operation class static String token; abstract public double operate (double x, double y); } class AddOp extends Operation { static String token = "+"; public double operate (double x, double y) { return x+y; } } //other operation classes SubOp, MulOp, DivOp class Challenge24Step { // represents one step in a solution Operation operator; double x, y; //operands double value; //the value of the step (x operator y) public Challenge24Step (Operation operator, double x, double y) { this.operator = operator; // constructor code; } public String toString () { return String.format("%s %s %s = %s", this.x, this.operator.token, this.y, this.value); } } </code></pre> <p>The problem is that it still gets token from the Operation class: "null"</p> <p>I understand that this is probably because operator is declared as Operation, but I don't understand why it doesn't go through standard inheritance: instance, class, each superclass</p> <p>How would I rearrange the script so that the more specific operation classes' tokens are used?</p>
 

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