These exercises are designed to support Lecture 7 Classes and Inheritance and Lecture 8 Unit Testing. Create a new folder in your work directory h:\work\at-m42 called lab2. Store the solutions to the exercise in separate groovy files labelled lab2-ex11.groovy, lab2-ex12.groovy, etc.

Put the following comment at the top of each script:

// Lab 1: Exercise n.m
// Student number: 0123456

Develop a class to represent a Point in a two dimensional space with an x and y property. Include in the class the method moveBy, which moves the point by the x and y displacements given as method parameters.

Build on the Point class developed in Exercise 1.1 to develop the class Line, defined by its start and end points. Include in the class the method moveBy, to displace the line by some given amount. Also, include the methods isHorizontal, isVertical to determine the nature of the line and length to determine the distance between the end points (you will need the Math.sqrt() method).

Build on the Point class developed in Exercise 1.1 to develop the class Rectangle, defined by the position of its upper left corner (a Point) its width and its height. its start and end points. Include in the class the methods moveBy, getArea and getPerimeter. Method moveBy displaces the rectangle by a given amount. Methods getArea and getPerimeter calculate the area and perimeter, respectively, of the rectangle.

A news agent maintains a list of customers, including their name. For each customer, the news agent has a list of newspapers to be delivered to their home. Develop a system to list each newspaper and the quantity required.

In the following listing, class Point represents a point in a two-dimensional space. Complete the hierarchy rooted in the interface Quadrilateral. A rectangle is defined by the position of the upper left corner, height and width.

class Point {
   void moveBy(Integer deltaX, Integer deltaY) { ... }
 
// ----- properrties ------------------------
 
   def x
   def y
}
 
interface Quadrilateral {
	Integer abstract getArea()
	Integer abstract getPerimeter()
	void moveBy(Integer deltaX, Integer deltaY)
}
 
class Rectangle implements Quadrilateral {
 
// ----- properrties ------------------------
 
   def upperLeft
   def width
   def height
}
 
class Square extends Rectangle {
}
 
def rect = new Rectangle(upperLeft : new Point(x : 0, y : 10), width : 10, height : 5)
rect.moveBy(2, 4)
 
println "rect: ${rect.getArea()}, ${rect.getPerimeter()}" // output: 50, 30
 
def sq = new Square(upperLeft : new Point(x : 0, y : 10), width : 10, height : 10)
println "sq: ${sq.getArea()}, ${sq.getPerimeter()}" // output: 100, 40

Extend the solution of Exercise 2.1 to ensure that the width and height properties of a square are always equal. Test using the following code fragment:

def sq = new Square(upperLeft : new Point(x : 0, y : 10), width : 10)
println "sq: ${sq.getArea()}, ${sq.getPerimeter()}" // output: 100, 40

You may need to copy some files from the Exercises for Lecture 8 and Case Study 3 before you begin.

1. Test that registering two Players with different id numbers to an empty Game results in two Players in the Game.
2. Test that an attempt to register a Player with the same id as one already registered results in no change to the number of Players in a Game.
3. Test that an attempt to register a Player with the same id as one already registered results in no change to the Player already registered.

The exercises are based on those given in Programming Groovy.

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