//Polygon.java MrG 2013.0208
import java.util.ArrayList;
public class Polygon
{
private ArrayList<Point> vertices;
public Polygon()
{
vertices = new ArrayList<Point>();
}
public void add(Point p)
{
vertices.add(p);
}
public String toString()
{
return "" + vertices;
}
public double getArea()
{
int stop=vertices.size();
double sum=0;
for(int i=0; i<stop;i++)
{
sum+=vertices.get(i).getX()*vertices.get((i+1)%stop).getY();
sum-=vertices.get((i+1)%stop).getX()*vertices.get(i).getY();
}
return sum/2;
}
}