Java Playground - Quadratic Expression Solver (Julian Challenge Answer): Online Interpreter, Compiler & Editor

JAVA
java
/*Example:
input line for function: 3x^2 + 5x + 3
input line for argument: 2
Solution = 25
Note: You can input either integers or floating point
      numbers for your argument or coefficients
*/
import java.util.Scanner;
public class Program
{
    public static void main(String[] args) {
        try{
            Scanner input = new Scanner(System.in);
            StringBuilder fx = new StringBuilder(input.nextLine());
            System.out.println("f(x) = " + fx); 
            while (fx.toString().contains(" ") || fx.toString().contains("+")){
            if (fx.indexOf(" ") != -1)
                fx.deleteCharAt(fx.indexOf(" "));
            if (fx.indexOf("+") != -1)
                fx.deleteCharAt(fx.indexOf("+"));
            }
            double arg = input.nextDouble();
            String[] coefficients = fx.toString().split("x\\^2|x");
            if (coefficients.length != 3)
               throw new Exception("Invalid function");
            System.out.printf("Therefore, f(%.3f) = %.3f", arg, computeQuadratic(arg, coefficients));
        }
        catch(Exception ex){
OUTPUT