SOFT2201/COMP9201 Week 3 Tutorial

• Outline the access level associated with each field

• Does either sub-type of Canine override one of its methods?

Question 2: Associations

Analyse the UML diagram and identify and answer the following:

• Outline all the associations within the UML Diagram

• How many Aeroplanes can a Hangar contain? Annotate the multiplicity of the association

• How many Tickets can a Customer hold? Annotate the multiplicity of the association

• Identify any association relationships where an object cannot exist without at least one other type (Composition)

Question 3: Critiquing a model and Refactoring the design

You will be asked through the semester to identify software design issues and refactor them. Not only will this improve your ability to debug problems but will help understand and identify issues within a code base.

Common issues that arise from improper modelling:

• Weak base classes

• Improper parent or interface type associated

• Repetitive logic and data

• Class dependent on other classes

• Classes performing more functionality than it should be

• Misassigned responsibility to an object

Given the following class diagram, discuss with your class and identify issues with the design.

Question 4: Extract Pokemon

You have been given a file that stores pokemon data called pokedex . json. Use the simple- json library as a way to read the pokedex.json file and output the contents.

You can add the dependency to your project by adding the following to the dependecies section in your gradle.build file.

implementation ’com .googlecode . json-simple:json-simple:1 . 1 . 1’ The element within pokedex.json file is in the following layout:

{

"kanto_no" : ,

"type_1" : first_type ,

"type_2" : second_type ,

"pokemon" : name

}

Import the following types into your project and attempt to parse the pokedex . json  file .

import org . json .simple .JSONArray;

import org . json .simple .JSONObject;

import org . json .simple .parser .JSONParser ;

JSON-Simple provides some examples in its wiki, you can access this here.

Read the contents of the file into a String object and utilise the .parse method to interpret the data into a JSONArray. You may need to apply a cast on the return result.

Command-query Separation

Command-query separation principle within imperative and object-oriented programming asks the programmer to design their methods to only perform a command or a query.  A command mutates and operates on the data provided or the instance itself. A query will not mutate data but provide an answer when invoked.

Question 5: Refactor the code

Identify methods which violate command-query separation and refactor the code, this may require breaking the code up into different functions.

public class Product {

private String  name ;

private int qty;

private int max;

private double price ;

/ **

*  Constructs  the  product,  providing  name  and  quantity

*  @param  name

*  @param  qty */

public Product (String  name , int qty , int max , double price)  { this .name  =  name ;

this .qty  =  qty;

this .max  =  max;

this .price  =  price ;

}

public Object  process (String  request , double value)  {

if (request .equals ( "getqty" )  {

return new Integer (qty);