Has one abstract and two regular classes  - Has two interfaces (the two regular classes have to implement at least one interface - At least one regular class must implement both interfaces  - The two classes have to extend the abstract class - The abstract class must have a method - At least one interface must have a method - At least two fields in each class, this includes the superclass - All fields are instantiated within the constructor

Interfaces are used to define stronger is-a relationships because one class can inherit multiple interfaces.  Ture or false

QUESTION 5 All methods in an abstract class must also be declared abstract. True False QUESTION 6 All fields declared in an interface are treated as final and static have protected access must be initialized in the class implementing the interface have private access

QUESTION 16 What must be true of a class with one abstract method? O The class must also implement the Iterable interface Any derived class must implement the method The abstract method must have the static modifier O The method cannot specify a return value QUESTION 17 Suppose we wanted to design a set of classes for a veterinarian's office. Our Customer class looks like this: public class Customer { Pet [] pets; } Select all the statements that are true Once the size of the pets array has been set, it cannot be changed Because we're using an array, all pets must be the same A customer must have at least one pet We also need to declare a Pet class QUESTION 18 What is the proper use of an enumeration? To define a set of ordered values To enforce the use of the Comparable interface O To define, or enumerate, the values returned by a Random object generator O To define the classes in an inheritance hierarchy

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…

When should one use an abstract class, when should one use an interface, and when should one use both?

Write a java This class must implement the model in the following UML class diagram.    Account -balance:  double +Account(init_balance : double) +getBalance( ): double +deposit(amount : double) Diagram object’s description: balance holds the current balance of the bank account Account sets balance to init_balance get balance retrieves the current balance deposit adds the amount parameter to the current balance (Hint: “-“ indicates private and “+“  indicates public)

Create a Java program demostrating the following aspects of OOP: You must create an UML. class diagram for all the classes and interfaces in the program. Use Java interface and method overriding appropriately. Inheritance/Interface and polymorphism. Your program the base class of interface should be used as the variable/parameter type to demostrate polymorphism. Overloading using either methods or constructors. Appropriate use of this keyword. Correct use of access modifiers (public, private) in an appropriate way. Correct use of static variable and instance variable. Passing object as parameter to a method. Caling method from another method of the same class. Creating user defined classes with Encapsulation principle consideration.   You are free to pick any topic/system to accomodate the above points but please keep it simple. The application does not have to be real world application meaning you can use an imaginary system for the mentioned points. Neverthless, you should be aware…

Question:   Mr. Hamza is working as an accountant in the Octal Company. He wants to calculate salary of his company employees. Develop a java program to calculate salary using the concept of abstract based on the following instructions. Save the project/file as AccountantYourID.                            A) Abstract Class name: YourFirstName_Octal        Abstract Member Method: –   to calculate and return salary    salary()  B) Class name:  Employee extends YourFirstName_Octal       Member variables:  wage, noOfDays, bonus       Member Method : –   parameterized constructor to initialize  member variables –   to calculate and return salary    salary = (wage3 * noOfDays) / 4 + bonus  C) Controlling class :   –   To create an object of Employee –   To print  salary of the Employee –  To print bonus of Employee

Java Programming Following the specifications given in the following detailed UML diagram, develop or modify all required classes: Design the Payroll interface, having the following two methods: calculateMonthlyGrossPay(): double displayPayInfo(): void - displays the information of the employee, followed by the information about the pay for a month Modify Person.java to show that it implements Payroll interface - you will not implement the interface methods here, which will change the type of class Person is; Modify Student, Employee, and Faculty to express the fact that they inherit behavior from Person that includes Payroll. You do not implement any of the methods from the Payroll interface in any of these classes.  Design Graduate class as a subclass of Student.  This class inherits the attributes and behavior of Student.  The class has an additional attribute: department: String - the department student is registered in. Create the accessor and mutator methods for a new…