Polynomials not printing properly

I'm writing a program that is meant to take up to two user input polynomials (input in a user friendly format like "2x^2+3x-4"), store them into two doubly linked lists, and then allow the user to add the polynomials together and output the result. I have the program accepting the user input and parsing the polynomials, but during some testing where I was just having the program output the polynomials again, I found that it was outputting them incorrectly.

Here's my current class to create the nodes, sort them into their respective list, and a method to then print those lists:

package polynomialAdder; public class PolyList { private PolyNode head; public PolyList() { this.head = null; } public PolyList(String poly) { this.head = null; String[] component = poly.split("\\+\\-"); //split based on "+" and "-" operators for(String term : component) { term = term.trim(); int coe, exp; if(term.contains("x")) //check if given term has an exponent and set it as such, otherwise set exp to 0 and omit "x^" { String[] parts = term.split("x\\^?"); coe = Integer.parseInt(parts[0]); exp = (parts.length == 2) ? Integer.parseInt(parts[1]) : 1; } else { coe = Integer.parseInt(term); exp = 0; } insertionSort(new PolyNode(coe, exp)); } } private void insertionSort(PolyNode newNode) { if(head == null || newNode.exp > head.exp) //sets the new node as the head if the list is empty or if its exponent is higher than that of the head { newNode.next = head; head = newNode; } else //traverses through the list, adding coefficients together if they share an exponent { PolyNode current = head; while(current.next != null && current.next.exp >= newNode.exp) { if(current.next.exp == newNode.exp) { newNode.coe += current.next.coe; newNode.next = current.next.next; current.next.next.prev = newNode; current.next = newNode; } current = current.next; } newNode.next = current.next; current.next = newNode; } } public void print() { PolyNode current = head; StringBuilder result = new StringBuilder(); while(current != null) { result.append(current.coe).append("x^").append(current.exp); if(current.next != null && current.coe < 0) { result.append("-"); } else if(current.next != null && current.coe > 0) { result.append("+"); } current = current.next; } System.out.println(result); } }

And this is my current main method:

package polynomialAdder; import java.util.*; public class Main { public static void main(String[] args) { Scanner polyScan = new Scanner(System.in); System.out.println("Enter first polynomial. Please use ^ to indicate exponents"); String polyA = polyScan.nextLine(); PolyList poly1 = new PolyList(polyA); System.out.println("Enter second polynomial. Please use ^ to indicate exponents"); String polyB = polyScan.nextLine(); PolyList poly2 = new PolyList(polyB); polyScan.close(); poly1.print(); poly2.print(); } }

Node class:

package polynomialAdder; public class PolyNode { int coe; int exp; PolyNode next; PolyNode prev; PolyNode(int coe, int exp) { this.coe = coe; this.exp = exp; this.next = null; this.prev = null; } }

To be clear, the two calls of the print() method in main are not final. I was using them for testing to ensure that the lists were being populated properly.

The issue I'm having is that I'm getting incorrect outputs from the print() method.
If I put in "2x^2+3x-4" for example, the output I get is "2x^1", which I am noticing is tied to the else of my conditional operator, but I can't quite parse why it's giving me this output.