L07 - Shapes Lab

In this lab, we'll work with Abstract Classes.

1. Start VS Code.
2. During the lecture we discussed the following classes:
   • Shape – an abstract class
   • Circle – a class that is derived from Shape
   • Ellipse – a class that is also derived from Shape
3. Using the Circle class a guide and the Ellipse slide, finish writing the Ellipse class
4. Using the Circle class as a guide, write a class called Rectangle:
   • extend the Shape class
   • define member variables of type double for the width and height
   • create one or more constructors, as appropriate
   • override the equals, toString, findArea, and findPerimeter methods
5. Create a new class with the name ShapeTest.
6. This is the body of the class ShapeTest:

public class ShapeTest {
    public static void main(String[] args) {
        Shape[] myShapes = new Shape[10]; 
        Circle myCircle = new Circle(10.0); 
        double expected = 314.16; 
        System.out.println("Circle Area: " + myCircle.findArea());

        myShapes[0] = new Circle(10.0); 
        expected = 314.16; 
        System.out.println("Circle in Shapes Array Area: " + myShapes[0].findArea());

        myShapes[1] = new Ellipse(5.0, 10.0);
        expected = 157.08;
        System.out.println("Ellipse in Shapes Array Area: " + myShapes[1].findArea());

        myShapes[2] = new Rectangle(5.0, 10.0); 
        expected = 50.0; 
        System.out.println("Rectangle in Shapes Array Area: " + myShapes[2].findArea());
    } 
}

When you run the tests, notice that Java knows what particular kind of object (Circle, Rectangle, or Ellipse) has been stored in the array of Shapes.