Thread: Quadratuc Read Method

I have to write a read method for a quadratic class where a quadratic is entered in the form ax^2 + bx + c. The description for the class is this:

Add a read method that asks the user for an equation in standard format and set the three instance variables correctly. (So if the user types 3x^2 - x, you set the instance variables to 3, -1, and 0). This will require string processing you have done before. Display the actual equation entered as is and properly labeled as expected output.

I was able to do the ax^2 part by using string manipulation and if else statements. But I am not sure how to do the bx and c parts of the equation because of the sign that could be in front of bx and c. Here is how I did the ax^2 part of the method.

 
public void read()
{
    Scanner keyboard = new Scanner(System.in);
    System.out.println("Please enter a quadratic equation in standard format.");
    String formula = keyboard.next();
    String a = formula.substring(0, formula.indexOf("x^2"));
    int a2 = Integer.parseInt(a);
    if (a2 == 0)
    {
        System.out.println("a = 0");
    }
    else if (a2 == 1)
    {
        System.out.println("a = 1");
    }
    else
    {
        System.out.println("a = " + a2);
    }
 }

Feel free to make edits and write new code for the method.
Any help would be greatly appreciated.

It could be any various combination of things it could be ax^2-c, bx+c, ax^2-bx+c, ax^2. It's supposed to work for all the different possibilities. But the only signs will be + and - . But a,b, and c will always be whole integers. And the number represented by a will always be with x^2 and so on. Also if the equation was x+3, a must be set equal to 0, b would be set equal to 1 and c would be 0.

Yes that is the case it seems. But I am unsure of how to do that.

A <expr> would be made up of either ax^2, bx, or c. a, b, and c are represented by integers in the actual equation. A <sign>would be represented by a plus or minus. Nothing separates an <expr> from a <sign>. The user inputs an equation such as this example: 3x^2-16x+8

Yes the next character would be an x in the cases of a and b, but not for c. I'm getting there though.