public class ProjectileSimulator {

    double x=0, y=0;             // Track (x,y) 
    double vx, vy;               // Velocity components
    double d;                    // Distance traveled


    public double run (double mass, double angle, double initialVelocity, double endTime, double timeInterval)
    {
        // Initialize values.
        double delT = timeInterval;               // Interval of time.
        double t = 0;                             // Current time.
        double g = 9.8;                           // 9.8 N - to be explained.
        double theta = Math.toRadians (angle);    // Convert degrees to radians.
        d = 0;
        x = 0;
        y = 0;
        
        // Initial vx = component of initialVelocity in x-direction.
        vx = initialVelocity * Math.cos (theta);
        // Initial vy = component of initialVelocity in y-direction.
        vy = initialVelocity * Math.sin (theta);

        while (t < endTime) {
            // Apply g to vy. Note: vx stays the same.
            vy = vy - g * delT;
            
            // Apply vx to x.
            double nextX = x + vx * delT;
            
            // Apply vy to y.
            double nextY = y + vy * delT;

            // Update total distance travelled.
            d = d + distance (x,y, nextX, nextY);

            // Set new (x,y)
            x = nextX;
            y = nextY;

            t = t + delT;
        }
        
        return d;
    }
    

    double distance (double x1, double y1, double x2, double y2)
    {
        return Math.sqrt ((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2));
    }
    

    public double getD ()
    {
        return d;
    }

    public double getX ()
    {
        return x;
    }
    

    public double getY ()
    {
        return y;
    }

}