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1.A system offers four service classes A, B, C and D, which differ in price tag and have a distinctive public method doA(), doB(), doC(), and doD(), respectively. These classes do share an identical public feature doCommon() method. The price attribute is private and is declared only once somewhere to be shared by all service classes. To use the system, a selected service is first paid for and the corresponding object is created to run the distinctive method and then the doCommon() method. Show the UML class diagram for the system. Extra interfaces, classes or methods can be added if needed
2.Today, the distinctive methods are changed to a private visibility. This however limits a created object to call its own method. Redesign the system to solve the problem by calling a public method doJob() and utilizing polymorphism and dynamic binding to provide the distinctive service for a selected class. Extra interfaces, classes or methods can be added if needed.
3. Show only the program statements inside the doJob() method for class A
3.
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- Draw the following Class Structure as a (class digram): 1. NotificationSystem: This is the main class that manages the notification system. It has the following attributes and methods: - Attributes: - users: a list of User objects representing all the users registered in the system - tweets: a list of Tweet objects representing all the tweets posted in the system - Methods: - register_user(user): adds a new user to the system - post_tweet(user, message): posts a new tweet on behalf of a user - get_timeline(user): returns a list of tweets from all users that the specified user follows - get_mentions(user): returns a list of tweets that mention the specified user 2. User: This class represents a user in the system. It has the following attributes and methods: - Attributes: - username: a string representing the username of the user - followers: a list of User objects representing all users who follow this user - following: a list of User objects representing all…arrow_forwardQuestion 1 Consider: class Car { ? } public Car() { } What happens if you try to run new Car(); A new object is created A new class is created It does not run Nothing happensarrow_forwardSolve the system using Design the Class Diagram (that contains at least 10 classes, show appropriaterelationships, multiplicities, attributes, and methods) (Examplearrow_forward
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