SENG2200 Assignment 1 Solution

1. Objectives
This assignment aims to build the understanding of Java programming in topics of class, inheritance, interface and circular doubly-linked data structure. A successful outcome should be able to demonstrate a solution of the assignment tasks with correct Java implementation and report.

2. Problem Statement
You are to write a program for a Stock and Station Agent based in Denman, NSW. Your program will be used to compare different land parcels for their value and how appropriate they are for particular types of agriculture as well as soil conservation and possible pasture improvement.
Unfortunately, this firm, while willing to trust your programming expertise, finds software development very confronting, and so does not trust things like standard libraries for data structures.
public interface ComparePoly {
boolean ComesBefore(Object o); // true if this < param }




2.1 Written Report
As you design, write and test your solution, you are to keep track of and report (max. 3 pages) on the following:
1. Keep track of how much time you spend designing, coding and correcting errors, and how many errors you need to correct.
2. Keep a log of what proportion of your errors come from design errors and what proportion from coding/implementation errors.
3. Given what we have covered in Topic 3 (Inheritance), how could you treat Rectangles and Squares as special cases of this assignment?

2.2 Point Class
Design and write a Point class. The Point class simply has two double-precision floating point values for x and y coordinate values. It has a method that will calculate the distance of the point from the origin. Your Point class should also contain a toString( ) method which will allow the conversion of a Point object into a String of the form (x , y) – include the open and close parentheses and the comma in the String. Note that toString() method (throughout this assignment) should return a string rather than print it out. The x and y values will appear in the string formatted according to the 4.2f specification. The string returned will be used for the output of your results.

2.3 Polygon Class
Design and write a Polygon class which contains a sequence of Point objects representing the ordered vertices of the polygon. Your Polygon class should contain a toString( ) method which will allow the conversion of a Polygon object into a String of the form
[point0point1…pointn-2]: area
For the area values, the format to be used is 6.2f. This will be used for output of your results. The Polygon class has a method that will calculate the area of the polygon, given by the formula in Section 3.
You will also need a method to return the distance from the origin of the pointi vertex which is closest to the origin. Polygon will implement a ComparePoly interface as per the above, and the Polygon comparison specification given below.
For any two polygons, if their area difference is within 0.1% of the smaller polygon, then they are assumed to have equal area. In these cases of equal areas, the polygon with the lower minimum vertex distance from the origin, takes precedence (comes first in your list – Section 2.4).

2.4 Data Structure
You are required to implement a circular doubly-linked list data structure with the class name of MyPolygons, using a single sentinel node to mark the start/finish of what will become a container for Polygon objects. The MyPolygons class must provide distinct methods to
• prepend items into the start of the list (current item will be the new first in list),
• append items into the end of the list (current item will be the new first in list),
• insert before a specified (current) item,
• step to the next item (making it the current item),
• reset the current item variable to the start of your list, and,
• take (then remove) an item from the head of the list.


2.5 Required Processing
• Read polygon specifications (until end of file, from standard input) and place them into an instance of your container, in input order.
• Output for your assignment is a complete print of both your lists, ie: the polygons in input order, and then the polygons in sorted order, listing the area of each polygon in each case, as per the Polygon specification of toString( )given above.


2.6 Input and Output
All input (coming from standard input) of polygons will be from a user-defined text file. That is, your program should be able to read polygons from a text file. A sample test file is as follows (you should create one for self-testing before submission):

P 6 4 0 4 8 7 8 7 3 9 0 7 1
P 3 4.1 0.0 4.0 8.2 7.3 8.4
P 5 4.0 0 4 8.1 7.2 8 7 3 9 0


All output is to the standard output. A sample output of the above input is as follows:
Unsorted list
[(4.00 , 0.00)(4.00 , 8.00)(7.00 , 8.00)(7.00 , 3.00)(9.00 , 0.00)(7.00 , 1.00)]: 24.50
[(4.10 , 0.00)(4.00 , 8.20)(7.30 , 8.40)]: 13.54
[(4.00 , 0.00)(4.00 , 8.10)(7.20 , 8.00)(7.00 , 3.00)(9.00 , 0.00)]: 27.66
Sorted list
[(4.10 , 0.00)(4.00 , 8.20)(7.30 , 8.40)]: 13.54
[(4.00 , 0.00)(4.00 , 8.00)(7.00 , 8.00)(7.00 , 3.00)(9.00 , 0.00)(7.00 , 1.00)]: 24.50
[(4.00 , 0.00)(4.00 , 8.10)(7.20 , 8.00)(7.00 , 3.00)(9.00 , 0.00)]: 27.66




3. Polygon Area Calculation
The area of a polygon, specified on the Cartesian plane by its vertices, is given as follows:
𝐴 𝑥 𝑥 𝑦 𝑦

Note: that for a seven-sided figure, such as the one shown, 𝑛 8, because the last point describing the polygon is equal to the first (it is always the same Cartesian point).

• https://rechneronline.de/pi/simple‐polygon.php

4. Programming Language

I will double-check this and issue an update when confirmed next week, but I believe this to be Java 11.0 (LTS).



5. Submission
Submission is through the Assignments tab for SENG2200 on Canvas under the entry
Assignment 1. If you submit more than once then only the latest will be graded. Every submission should be ONE ZIP file (not a .rar, or .7z, or etc) named c9999999.zip (where c9999999 is your student number) containing:
• Report (PDF file): addresses the tasks in Section 2.1.
• Program source files.
Programming is in Java, as per section above. Place all your files in the submission root.

Name your startup class A1.java (capital-A number-1), that is, the marker will compile your program with the command: javac A1.java
…and to run your program with the command: java A1 test.dat
…within a Command Prompt window.





Dan and Nan
v1.0 (20220-02-25)


Appendix I - Marking Criteria
This guide is to provide an overview of Assignment 1 marking criteria. It briefly shows the mark distribution. This guide is subject to adjustment without notice.

Program Correctness
• ComparePoly Interface (5%)
• Point class o Incl. required methods (10%)
• Polygon class o Incl. required methods (15%)
• MyPolygons class
o Circular doubly-linked data structure (20%)
o Insertion sort (5%)
o Other methods (e.g., prepend and append) (15%)
• Input/Output (10%)
Report

Miscellaneous (10%)
• Code Format & Comments (10%)
Deductions
• Errors with filenames, submission, execution, and mathematical results will attract penalties