Charge.java in programe

Charge.java

public class Charge

{

    private double rx, ry;  

    private double q;       

    public Charge(double x0, double y0, double q0)

 {

        rx = x0;

        ry = y0;

        q  = q0;

    }

    public double potentialAt(double x, double y)

    {

        double k = 8.99e09;

        double dx = x - rx;

        double dy = y - ry;

        return k * q / Math.sqrt(dx*dx + dy*dy);

    }

    public String toString()

   {

        return q + " at " + "(" + rx + ", " + ry + ")";

    }

    public static void main(String[] args)

   {

        double x = Double.parseDouble(args[0]);

        double y = Double.parseDouble(args[1]);

        Charge c1 = new Charge(.51, .63, 21.3);

        Charge c2 = new Charge(.13, .94, 81.9);

        System.out.println(c1);

        System.out.println(c2);

        double v1 = c1.potentialAt(x, y);

        double v2 = c2.potentialAt(x, y);

        StdOut.println(v1+v2);

    }

}