如何绘制用于函数调用的控制流图（调用图）？

Question

我已经看过很多CFG示例，但是它们都是过程内的。对于通常称为调用图的过程间CFG，我没有找到任何帮助。如何为以下代码绘制CFG？

public class AreaShape {

    public static void main() {
        Shape Obj = new Shape();
        int i = 0;

        while(i != 5) {
            System.out.println("You can enter 1 or 2 as your choice");
            System.out.println("Enter 1 to calculate the area of square");
            System.out.println("Enter 2 to calculate the area of rectangle");
            Scanner sc = new Scanner(System.in);
            i = sc.nextInt();
            switch (i)
            {
            case 1:
                System.out.println("Area of Square =" + Obj .area(5));
                break;
            case 2:
                System.out.println ("Area of ractangle: " + Obj .area(5,6));
                break;
            default: 
                System.out.println("Enter valid number");
                break;
            }
        }
    }
}

public class Shape {

    int area(int l) {
        int a = l*l;
        return a;
    }   

    int area(int l, int w) {
        int a = l*w;
        return a;      
    }
}