Description
Introduction
This assignment tests your understanding of basic inheritance in Java.
You are asked to write a number of Java classes to model basic shapes:
Shape, Rectangle, Square and Diamond. Rectangle and Diamond are the
subclasses of Shape, and Square is the subclass of Rectangle
You are also required to write JavaDoc for all non-private classes and non-private class
members.
Implementation
The Shape class:
Methods
Shape()
Constructor, create an empty shape. A shape is typically a 2D array of pixels (boolean values).
String toString()
Return a drawing of the shape as a String. Each pixel should be represented by the character *
and each empty space should be represented by the space character. Newlines are represented by newline
character \n.
int getArea()
Return the area, i.e., the number of pixels in the shape.
Shape intersect(Shape s)
Return a new Shape object representing the intersection of this Shape object and s.
Shape union(Shape s)
Return a new Shape object representing the union of this Shape object and s.
The Rectangle class, a subclass of the Shape class:
Methods
Rectangle(int width, int height)
Constructor, create a rectangle with the specific width and height. For example, if
width = 5 and height = 3, a drawing of this shape will look like this:
*****
*****
*****
Shape
Rectangle Diamond
Square
The Diamond class, a subclass of the Shape class:
Methods
Diamond(int size)
Constructor, create a diamond shape with the specific size. For example, if size = 3, a
drawing of this shape will look like this (the empty area is represented by space characters
and each newline is represented by the newline character \n.):
*
***
*****
***
*
The Square class, a subclass of the Rectangle class:
Methods
Square(int size)
Constructor, create a square with the specific size. For example, if size = 3, a drawing of
this shape will look like this:
***
***
***
Grading
Your classes will be tested with a number of client programs. For example:
// ShapeTester.java
public class ShapeTester {
public static void main(String [] args) {
Square s = new Square(3);
System.out.println(s);
System.out.println(“Area is ” + s.getArea());
Diamond d = new Diamond(3);
System.out.println(d);
System.out.println(“Area is ” + d.getArea());
Shape union = s.union(d);
System.out.println(union);
System.out.println(“Area is ” + union.getArea());
Shape intersect = s.intersect(d);
System.out.println(intersect);
System.out.println(“Area is ” + intersect.getArea());
}
}
Return of toString():
Notice that there is no newline
character after the drawing
The following output is expected:
***
***
***
Area is 9
*
***
*****
***
*
Area is 13
***
****
*****
***
*
Area is 16
*
**
***
Area is 6
Notice that there is no empty line after the drawing.
– 80% marks are given to the correctness of your program by the Moodle evaluation system.
➢ You will see your marks immediately right after the evaluation.
➢ You can re-submit the assignment before the deadline. We only consider the latest
submission for final grading.
➢ Output format is critical to the evaluation. Make sure there are space characters and
newlines in proper locations in the program output.
➢ You are not recommended to declare any static variable in your program as a static
variable will keep data across test cases and make you difficult to debug.
➢ Normally, we will not release any test case. However, if you failed to pass a certain
test case, the expected output shown on the screen will give you some hints to debug
the your program.
– 20% marks are given to your JavaDoc and will be given manually after the due date. A
complete JavaDoc includes documentation of every classes, member fields and methods that
are not private.
– Economy is valuable in coding: the easiest way to ensure a bug-free line of code is not to
write the line of code at all.
Submission:
Please submit the following files to Moodle and evaluate. Late submission is not allowed.
Shape.java
Rectangle.java
Diamond.java
Square.java
If you got all the marks from the evaluation system (80% of the assignment), the grading report
would look like this.
