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POEncountering NullPointerException when trying to add polynoms
 

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  1. POEncountering NullPointerException when trying to add polynoms
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    <p>I need to add two polynomials, which is composed of two ints. For example, the coefficient and the exponent 3x^2 would be constructed using 3 and 2 as parameters. I am getting a NullPointerException but I can't figure out why. Any help would be appreciated!</p> <pre><code>public class Polynomial { private Node poly; public Polynomial() { } private Polynomial(Node p) { poly = p; } private class Term { int coefficient; int exponent; private Term(int coefficient, int exponent) { this.coefficient = coefficient; this.exponent = exponent; } } private class Node { private Term data; private Node next; private Node(Term data, Node next) { this.data = data; this.next = next; } } public void addTerm(int coeff, int exp) { Node pointer = poly; if (pointer.next == null) { poly.next = new Node(new Term(coeff, exp), null); } else { while (pointer.next != null) { if (pointer.next.data.exponent &lt; exp) { Node temp = new Node(new Term(coeff, exp), pointer.next.next); pointer.next = temp; return; } pointer = pointer.next; } pointer.next = new Node(new Term(coeff, exp), null); } } public Polynomial polyAdd(Polynomial p) { return new Polynomial(polyAdd(this.poly, p.poly)); } private Node polyAdd(Node p1, Node p2) { if (p1 == p2) { Term adding = new Term(p1.data.coefficient + p2.data.coefficient, p1.data.exponent); p1 = p1.next; p2 = p2.next; return new Node(adding, null); } if (p1.data.exponent &gt; p2.data.exponent) { p2 = p2.next; } if (p1.data.exponent &lt; p2.data.exponent) { p1 = p1.next; } if (p1.next != null &amp;&amp; p2.next != null) { return polyAdd(p1, p2); } return new Node(null, null); } } </code></pre> <p>import javax.swing.JOptionPane;</p> <p>/** * * @author Bill Kraynek */ public class Polynomials {</p> <pre><code>/** * @param args the command line arguments */ public static void main(String[] args) { Polynomial p1 = new Polynomial(); Polynomial p2 = new Polynomial(); Polynomial p0 = new Polynomial(); p1.addTerm(5, 2); p1.addTerm(4, 5); p1.addTerm(3, 3); p1.addTerm(1, 2); p1.addTerm(5, 6); p2.addTerm(3, 8); p2.addTerm(2, 5); p2.addTerm(1, 3); Polynomial p3 = p1.polyAdd(p2); JOptionPane.showMessageDialog(null, "p1 is " + p1 + "\np2 is " + p2 + "\np1+p2 is " + p3); // Polynomial p4 = p1.polyMultiply(p2); // JOptionPane.showMessageDialog(null, "p1 is " + p1 + "\np2 is " + p2 + "\np1*p2 is " + p4); // Polynomial p5 = p2.polyMultiply(p2); //JOptionPane.showMessageDialog(null, "p2 is " + p2 + "\np2*p2 is " + p5); // Polynomial p6 = p0.polyMultiply(p2); //JOptionPane.showMessageDialog(null, "p0 is " + p0 + "\n" + "p2 is " + p2 + "\np0*p2 is " + p6); Polynomial p7 = p0.polyAdd(p2); JOptionPane.showMessageDialog(null, "p0 is " + p0 + "\n" + "p2 is " + p2 + "\np0+p2 is " + p7); p1 = p1.polyAdd(p2); JOptionPane.showMessageDialog(null, "After p1 = p1+p2 p1 is " + p1); // p2 = p2.polyMultiply(p2); JOptionPane.showMessageDialog(null,"After p2 = p2*p2 p2 is " + p2); } </code></pre> <p>} some lines are // because i dont have the second method yet</p> <p><a href="http://users.cis.fiu.edu/~kraynek/COP3337-assignments/Spring-2012/AssignmentFive-Polynomials-Spring-2012.html" rel="nofollow">http://users.cis.fiu.edu/~kraynek/COP3337-assignments/Spring-2012/AssignmentFive-Polynomials-Spring-2012.html</a></p>
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    1. PO
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    1. This table or related slice is empty.
    1. PTQuestion
    1. USAyler Cruz
    1. USAyler Cruz
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
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      1. PTAnswer
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      1. POEncountering NullPointerException when trying to add polynoms
      1. This table or related slice is empty.
      1. VTApproveEditSuggestion
    1. COCan you provide the stack trace where you're getting the exception?
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      1. POEncountering NullPointerException when trying to add polynoms
      1. USLouis Wasserman
    2. COAlso, please add the [homework] tag on homework.
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      1. POEncountering NullPointerException when trying to add polynoms
      1. USLouis Wasserman
    3. COWe need to know what is actually happening and where your program is throwing and Exception or not compiling. I would also suggest including some kind of main method so that we can test it ourselves.
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      1. POEncountering NullPointerException when trying to add polynoms
      1. USAustin Heerwagen
 

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