Programming 3

Base project

Download the base Eclipse project for this assignment, which already contains some classes and unit tests. Import it as a Java project in Eclipse.

Coordinate

This class represents a two-dimensional coordinate. Three constants are defined in it:

• NOT_VALID : indicates an invalid numeric value for the components of a coordinate.
• MAX_VALUE : maximum positive value that the component of a coordinate can take (32767.9999).
• MIN_VALUE : negative minimum value that the component of a coordinate can take (-32767.9999).

Three constructors are available for Coordinate: the default constructor, the copy constructor and an overloaded constructor. The default constructor assigns invalid values to the coordinate components. The overloaded constructor allows constructing coordinates with given initial values, as long as they are within the range of maximum and minimum values allowed. If not, this constructor will throw the unchecked exception IllegalArgumentException.

There is also a pair of getters to get the coordinate component values, the toString() method to get a string representation of it and the equals() method that will return true when both coordinate components being compared are equal. In addition, we have the following two methods to operate on coordinates:

• sum(Coordinate) : it returns a new coordinate resulting from adding two other coordinates:

Coordinate c1, c2;
...
Coordinate c3 = c1.sum(c2);

• subtract(Coordinate) : works in the same way as the previous method, but returns a coordinate resulting from subtracting two other coordinates.

Both operations may produce coordinates with out-of-range values. In those cases they will throw the unchecked exception ArithmeticException.

Form2D

This abstract class is the root of the class hierarchy by which we model two-dimensional figures. As you can tell from a quick glance at the UML diagram, the figures in our model have a position in the plane, specified by a Coordinate object; this property has its respective getter. In addition, these figures can be moved (move()), scaled (scale()) and cloned (clone()).

Constructors:

• Form2D() : creates a figure with an invalid position.
• Form2D(Coordinate) : creates a figure with the given position.
• Form2D(Form2D) : copy constructor.

Methods:

• getPosition() : getter to get the position of a figure.
• move(Coordinate) : moves a figure to the position given by the argument and returns the old position of the figure. If the argument is null it does not change the position and simply returns the current position.
• equals(Object) : returns true if the compared figures have equal positions.
• toString() : returns a string representing the figure with the following format:

(<x>,<y>)

where <x> and <y> are the components of the figure’s position. For example, for a figure at position (-30.4, 27.1):

(-30.4,27.1)

• clone() : abstract method to be implemented by subclasses of Form2D that returns a copy of the figure.
• clone(Coordinate) : returns a copy of the figure, translated to the position specified by the argument.
• scale(double) : abstract method to be implemented by subclasses of Form2D to scale the dimensions of a figure. The scaling percentage is specified by the argument, with respect to the current dimensions of the figure and can have any positive value greater than zero. For example, a value of 100 indicates keeping the dimensions of the figure unchanged. A value of 50 would indicate halving the dimensions and a value of 200 would indicate doubling the dimensions of the figure. This operation does not alter the position of a figure. It throws IllegalArgumentException if the specified percentage is negative or zero.

Circle

Subclass of Form2D that models a circle. The centre of the circle corresponds to the position of the figure (in Form2D) and its radius is specified by the radius attribute, which cannot be negative.

Constructors:

• Circle() : creates a circle of radius zero and no defined centre.
• Circle(Circle) : copy constructor
• Circle(Coordinate, double) : creates a circle with the centre and radius given as arguments. It throws IllegalArgumentException if the given radius is negative.

Methods:

• getRadius() : getter for radius.
• scale(double) : implements the scale() method of Form2D. A circle is scaled by modifying its radius by the percentage indicated by the argument (see Form2D.scale() for details).
• clone() : returns a copy of this circle.
• toString() : returns a string representing the state of the Circle object, in this format:

(<x>,<y>),radius=<r>

where <x> and <y> are the components of the figure’s position, and <r> is its radius value. For example, for a circle at position (-30.4, 27.1) with radius 3.5:

(-30.4,27.1),radius=3.5

• equals(Object) : returns true if the object passed as an argument is a circle and has the same centre and radius as this circle.

AbstractPolygon

This abstract class inherits from the Form2D class and is the base class for all the polygons modelled in our application. The polygons in our model have, in addition to the attributes inherited from Form2D, an angle indicating the rotation of the polygon; this property has its respective getter. Moreover, these figures can be rotated (rotate()). Note that although this class is abstract it does not define new abstract methods, but inherits the abstract methods of Form2D and does not implement them.

Constructors:

• AbstractPolygon() : Creates a polygon with a rotation angle of 0 and undefined position.
• AbstractPolygon(Coordinate,double) : Creates a polygon with the given position and rotation angle. It throws the exception IllegalArgumentException if the given angle is not in the range [0.0,360.0).
• AbstractPolygon(AbstractPolygon) : Copy constructor.

Methods:

• getAngle(): getter to get the rotation angle of a polygon.
• equals(Object): returns true if the polygons compared have equal positions and angles.
• toString(): returns a string representation of the polygon, in this format:

(<x>,<y>),angle=<angle>

where <x> and <y> are the components of the polygon’s position and <angle> its angle of rotation. For example, for a figure that is at position (-30.4, 27.1) and whose angle of rotation is 45.0°:

(-30.4,27.1),angle=45.0

• rotate(double): rotates a polygon by the number of degrees given as an argument, whose value must be in the range (-360.0,360.0). Otherwise the method throws an IllegalArgumentException. The rotation is performed by adding the angle received as an argument to the polygon’s angle. Note that the resulting rotation angle must be in the interval [0.0,360.0); so if, for example, the angle of the polygon is 45.0° and the rotation received as an argument is -90.0°, the resulting angle must be 315.0°.

Rectangle

Constructors:

• Rectangle() : creates a rectangle with a rotation angle, length and width equal to zero, and undefined position.
• Rectangle(Rectangle) : copy constructor
• Rectangle(Coordinate, double, double, double) : creates a rectangle with the position specified by the first argument, the rotation angle provided as second argument, and the length and width specified in the third and fourth arguments, respectively. The position of the rectangle is that of its upper left vertex. It throws IllegalArgumentException if the specified length or width is negative.

Methods:

• getLength() and getWidth() : getters for the length and width, respectively.
• scale(double) : implements the scale() method of Form2D. A rectangle is scaled by modifying its length and width in the proportion indicated by the argument (see Form2D.scale() for details).
• clone() : returns a copy of this rectangle.
• toString() : returns a string representing the state of the rectangle object, in this format:

(<x>,<y>),angle=<a>,length=<l>,width=<w>

where <x> and <y> are the position components of the figure, <a> is its roration angle, and <l> and <w> are the value of its length and width, respectively. For example, for a rectangle at position (-30.4, 27.1), with length 2.5 width 7.0 and angle 45.0°:

(-30.4,27.1),angle=45.0,length=2.5,width=7.0

• equals(Object) : returns true if the object passed as argument is a rectangle and has the same position, angle, length and width as this rectangle.

Square

Constructors:

• Square() : creates a square with a side equal to zero, a rotation angle equal to zero and an undefined position.
• Square(Square) : copy constructor
• Square(Coordinate, double, double) : creates a square with the position indicated by the first argument, the rotation angle indicated in the second argument and the side indicated as the last argument. The position of the square is that of its upper left vertex. It throws IllegalArgumentException if the indicated side is negative.

Methods:

• getSide(): getter for the side.
• scale(double) : implements the scale() method of Form2D. A square is scaled by modifying its side in the proportion indicated by the argument (see Form2D.scale() for details).
• clone() : returns a copy of this square.
• toString() : returns a string that represents the state of the square object, with this format:

(<x>,<y>),angle=<a>,side=<s>

where <x> and <y> are the components of the position of the figure, <a> is its angle of rotation and <s> is the value of its side. For example, for a square that is in position (-30.4, 27.1), with side 2.5 and angle 45.0°:

(-30.4,27.1),angle=45.0,side=2.5

• equals(Object) : returns true if the object passed as an argument is a square and has the same position, rotation angle and side as this square.

Canvas

Canvas represents a canvas containing two-dimensional geometric figures. A canvas has a title and dimensions (whose default value is DEFAULT_SIZE), specified by the width and height attributes. The canvas contains a list of figures of type Form2D.

Constructors:

• Canvas() : creates a canvas without figures, with default dimensions and title "default canvas".
• Canvas(Canvas) : copy constructor
• Canvas(String, double, double) creates an empty canvas with the title (first argument) and the width and height specified by the second and third arguments, respectively. It throws IllegalArgumentException if the specified width or height is negative.

Methods:

• addForm(Form2D) : adds a figure to the canvas. It does not check whether the position of the figure is inside the canvas or not.
• clone() : returns a copy of this canvas.
• getWidth() and getHeight() : getters for the width and height of the canvas, respectively.
• getNumForms() : returns the number of figures that have been added to the canvas.
• getForm(int) : returns the n-th figure added to the canvas, starting at one. It throws IndexOutOfBoundsException if the given index is not between 1 and the total number of figures added to the canvas.
• removeForm(int) : removes the figure added at n-th position to the canvas, starting at one. It throws IndexOutOfBoundsException if the given index is not between 1 and the total number of figures added to the canvas.
• toString() : returns a string with the title and dimensions of the canvas, the number of figures it contains, and then a line for each figure added to the canvas. For example, if we have a canvas with the title “Prog3”, of width 1024 and height 768, with two circles and a rectangle, this method will return a string like this:

Prog3 (1024.0,768.0) with 3 forms

Form2DFactory

Factory class whose responsibility is to create figures of the Form2D hierarchy.

• createForm2D(String) : creates and returns the requested figure using the default constructor of its class. The method parameter shall contain the name of the figure class to create (Circle, Square or Rectangle). It throws IllegalArgumentException if the name of the figure is not Circle, Square or Rectangle.