Tracy marlatt branch

plan-for-extension-exercise/src/planForExtensionExercise/AreaCalculator.java

@@ -1,27 +1,24 @@
 package planForExtensionExercise;
 
 public class AreaCalculator {
-    public static double calculateArea(Object[] shapes) {
-        double area = 0.0;
-
-        if (shapes == null) {
-            return area;
-        }
-
-        for (Object shape : shapes) {
-            if (shape == null) {
-                continue;
-            }
-            else if (shape instanceof Circle) {
-                Circle circle = (Circle)shape;
-                area += Math.PI * circle.getRadius() * circle.getRadius();
-            }
-            else if (shape instanceof Rectangle) {
-                Rectangle rectangle = (Rectangle)shape;
-                area += rectangle.getHeight() * rectangle.getWidth();
-            }
-        }
-
-        return area;
-    }
+
+	// Calculates the aggregate area for an array of Shapes
+	public static double calculateArea(Shape[] shapes) {
+
+		double area = 0.0;
+
+		if (shapes == null) {
+			return area;
+		}
+
+		for (Shape shape : shapes) {
+			if (shape == null) {
+				continue;
+			}
+			else {
+				area += shape.getArea();
+			}
+		}
+		return area;
+	}
 }

plan-for-extension-exercise/src/planForExtensionExercise/Circle.java

@@ -1,13 +1,20 @@
 package planForExtensionExercise;
 
-public class Circle {
-    private double radius;
-
-    public Circle(double radius) {
-        this.radius = radius;
-    }
-
-    public double getRadius() {
-        return this.radius;
-    }
+public class Circle extends Shape {
+
+	private double radius;
+
+	public Circle(double radius) {
+		this.radius = radius;
+	}
+
+	// Computes its own area
+	public double getArea() {
+		return (Math.PI * this.radius * this.radius);
+	}
+
+	//Computes its own circumference
+	public double getPerimeter() {
+		return (2 * Math.PI * this.radius);
+	}
 }

plan-for-extension-exercise/src/planForExtensionExercise/Main.java

@@ -2,16 +2,20 @@
 
 public class Main {
 
-    public static void main(String[] args) {
-        Circle circle = new Circle(25);
-        Rectangle rectangle = new Rectangle(10, 20);
-        Rectangle square = new Rectangle(10, 10);
-
-        Object[] shapes = { circle, rectangle, square };
-
-        double totalArea = AreaCalculator.calculateArea(shapes);
-
-        System.out.println("The total area is " + totalArea + ".");
-    }
+	public static void main(String[] args) {
 
+		Circle circle = new Circle(25);
+		Rectangle rectangle = new Rectangle(10, 20);
+		Rectangle square = new Rectangle(10, 10);
+		Triangle triangle = new Triangle(3,4,5);
+
+		Shape[] shapes = { circle, rectangle, square, triangle };
+
+		double totalArea = AreaCalculator.calculateArea(shapes);
+		System.out.println("The total area is " + totalArea + ".");
+
+		double totalPerimeter = PerimeterCalculator.calculatePerimeter(shapes);
+		System.out.println("The total perimeter is " + totalPerimeter + ".");
+
+	}
 }

plan-for-extension-exercise/src/planForExtensionExercise/PerimeterCalculator.java

@@ -0,0 +1,24 @@
+package planForExtensionExercise;
+
+public class PerimeterCalculator {
+
+	// Calculates the aggregate perimeter for an array of shapes
+	public static double calculatePerimeter(Shape[] shapes) {
+
+		double perimeter = 0.0;
+
+		if (shapes == null) {
+			return perimeter;
+		}
+
+		for (Shape shape : shapes) {
+			if (shape == null) {
+				continue;
+			}
+			else {
+				perimeter += shape.getPerimeter();
+			}
+		}
+		return perimeter;
+	}
+}

plan-for-extension-exercise/src/planForExtensionExercise/Rectangle.java

@@ -1,19 +1,22 @@
 package planForExtensionExercise;
 
-public class Rectangle {
-    private double height;
-    private double width;
-
-    public Rectangle(double height, double width) {
-        this.height = height;
-        this.width = width;
-    }
-
-    public double getHeight() {
-        return this.height;
-    }
-
-    public double getWidth() {
-        return this.width;
-    }
+public class Rectangle extends Shape {
+
+	private double height;
+	private double width;
+
+	public Rectangle(double height, double width) {
+		this.height = height;
+		this.width = width;
+	}
+
+	// Computes its own area
+	public double getArea() {
+		return (this.height * this.width);
+	}
+
+	// Computes its own perimeter
+	public double getPerimeter() {
+		return (2*this.height + 2*this.width);
+	}
 }

plan-for-extension-exercise/src/planForExtensionExercise/Shape.java

@@ -0,0 +1,9 @@
+package planForExtensionExercise;
+
+public abstract class Shape {
+
+	// Subclasses implement the following methods
+	abstract double getArea();
+	abstract double getPerimeter();
+
+}

plan-for-extension-exercise/src/planForExtensionExercise/Triangle.java

@@ -0,0 +1,24 @@
+package planForExtensionExercise;
+
+public class Triangle extends Shape {
+
+	//Triangle may be scalene
+	private double side1, side2, side3;
+
+	public Triangle(double side1, double side2, double side3) {
+		this.side1 = side1;
+		this.side2 = side2;
+		this.side3 = side3;
+	}
+
+	// Computes its own area - using Heron's Formula
+	public double getArea() {
+		double s = 0.5 * getPerimeter();
+		return (Math.sqrt(s * (s-this.side1) * (s-this.side2) * (s-this.side3)));
+	}
+
+	//Computes its own perimeter
+	public double getPerimeter() {
+		return (this.side1 + this.side2 + this.side3);
+	}
+}