Refactoring - ocp

Attention.md

• How can I use circle, square, triangle and any shape that comes in future to draw?
• How can I draw pictures that are composed from triangles, squares, or circles or any future shape?
• I want to make sure that always circles are drawn first, squares are second and triangles are third?

Canvas.java

class Canvas {
  public void draw(Circle c) {
    System.out.println("Canvas drawing a circle.");
  }
  public void draw(Square s) {
    System.out.println("Canvas drawing a square.");
  }
  public void draw(Triangle t) {
    System.out.println("Canvas drawing a triangle.");
  }
  public void draw(List<?> shapes) {
    // loop through each shape and draw
    System.out.println("Canvas drawing a picture here using the square, circle etc...");
  }
}

Circle.java

class Circle {
  public void draw() {
    System.out.println("Drawing Circle...");
  }
}

Square.java

class Square {
  public void draw() {
    System.out.println("Drawing square....");
  }
}

Triangle.java

class Triangle {
  public void draw() {
    System.out.println("Drawing triangle....");
  }
}