OOP Concepts and UML

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Questions and Answers

Which keyword is used to declare a class as abstract?

abstract

Can an abstract class have any objects created from it?

No, abstract classes cannot have objects created from them

Is it necessary for a derived class to implement all the abstract methods of the base class?

Yes, it is necessary for the derived class to implement all abstract methods

Which one of the following is true about default methods in Java interfaces?

Default methods can be used to define optional methods in an interface. Signup and view all the answers

What is the strongest relationship that can exist among the Bank, Account, and Customer classes in a Java program?

Composition Signup and view all the answers

Which class extends the Bank class and overrides its getRateOfInterest() method?

Chase Signup and view all the answers

Which classes should implement the Account interface in a Java banking system program?

Bank, Account, and CurrentAccount Signup and view all the answers

Which one of the following statements is true about dependency in object-oriented programming?

A class has some sort of dependency on another class Signup and view all the answers

What does the «creates» stereotype indicate in an association relationship?

The source of the association creates the target Signup and view all the answers

What is the difference between aggregation and composition in object-oriented programming?

Aggregation indicates a part of a whole relationship, while composition indicates a whole to its parts relationship Signup and view all the answers

What is the purpose of extending an interface in object-oriented programming?

To inherit the methods and variables of another interface Signup and view all the answers

Which keyword is used to declare a class as final in Java?

final Signup and view all the answers

Which of the following is NOT a characteristic of interfaces in Java?

Interfaces can have instance variables Signup and view all the answers

What is the purpose of the 'implements' keyword in Java?

To indicate that a class implements an interface Signup and view all the answers

What is the correct syntax to implement multiple interfaces in Java?

class MyClass implements Interface1, Interface2 Signup and view all the answers

Which keyword is used to declare a class as abstract in Java?

abstract Signup and view all the answers

Can an abstract class have constructors?

Yes, an abstract class can have constructors. Signup and view all the answers

What is the purpose of an abstract method in a superclass?

To force subclasses to provide their own implementation of the method. Signup and view all the answers

Which of the following statements is true about default methods in Java interfaces?

Default methods can be overridden by implementing classes. Signup and view all the answers

What is the purpose of extending an interface in object-oriented programming?

To add additional methods to the extended interface. Signup and view all the answers

What is the difference between aggregation and composition in object-oriented programming?

Aggregation implies a whole-part relationship, while composition implies a has-a relationship. Signup and view all the answers

What is the correct syntax to implement multiple interfaces in Java?

class MyClass implements Interface1, Interface2 { } Signup and view all the answers

Which one of the following statements is true about the relationship between aggregation and composition in object-oriented programming?

Composition is a stronger relationship than aggregation. Signup and view all the answers

Which one of the following statements is true about inheritance in object-oriented programming?

Inheritance allows a class to inherit methods and fields from only one parent class. Signup and view all the answers

Which one of the following statements is true about interfaces in Java?

An interface can implement another interface. Signup and view all the answers

Which one of the following statements is true about the 'extends' and 'implements' keywords in Java?

An interface can use 'extends' to inherit from multiple interfaces. Signup and view all the answers

Which one of the following statements is true about final methods in Java?

Final methods cannot be overridden by subclasses. Signup and view all the answers

What is the purpose of interfaces in Java?

Interfaces allow you to fully abstract a class. Signup and view all the answers

Which of the following is true about default methods in Java interfaces?

Default methods have a body and can be overridden by implementing classes. Signup and view all the answers

What is the purpose of the 'implements' keyword in Java?

The 'implements' keyword is used to indicate that a class is implementing an interface. Signup and view all the answers

Study Notes

Abstract Classes

The keyword abstract is used to declare a class as abstract.
An abstract class cannot have objects created from it.
It is not necessary for a derived class to implement all the abstract methods of the base class.

Interfaces

Default methods in Java interfaces allow adding new functionality to an interface without breaking the implementing classes.
An interface can be extended by another interface.
Multiple interfaces can be implemented by a class using the implements keyword, separated by commas.

Class Relationships

The strongest relationship that can exist among the Bank, Account, and Customer classes in a Java program is composition.
A derived class can extend the Bank class and override its getRateOfInterest() method.
The classes that should implement the Account interface in a Java banking system program are those that represent types of accounts.

Object-Oriented Programming

Dependency in object-oriented programming is a relationship where one class uses another class.
The «creates» stereotype indicates a creation relationship in an association relationship.
Aggregation is a relationship where one class contains a collection of another class, while composition is a relationship where one class owns a collection of another class.
The purpose of extending an interface is to add new functionality or to create a new interface that is a modified version of the original interface.

Keywords

The keyword final is used to declare a class as final in Java.
Interfaces in Java cannot have instances created from them, and all methods are abstract.
The implements keyword is used to implement one or more interfaces in a class.
The correct syntax to implement multiple interfaces in Java is class MyClass implements Interface1, Interface2, ....
The keyword abstract is used to declare a class as abstract in Java.
Abstract classes can have constructors.

Methods

The purpose of an abstract method in a superclass is to provide a blueprint for a method that must be implemented by its subclasses.
Default methods in Java interfaces allow adding new functionality to an interface without breaking the implementing classes.
Final methods in Java cannot be overridden by subclasses.

Inheritance

Inheritance in object-oriented programming is a mechanism of creating a new class from an existing class.

Interfaces

The purpose of interfaces in Java is to define a contract that must be implemented by any class that implements it.

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OOP Concepts and UML

Questions and Answers

Which keyword is used to declare a class as abstract?

Can an abstract class have any objects created from it?

Is it necessary for a derived class to implement all the abstract methods of the base class?

Which one of the following is true about default methods in Java interfaces?

What is the strongest relationship that can exist among the Bank, Account, and Customer classes in a Java program?

Which class extends the Bank class and overrides its getRateOfInterest() method?

Which classes should implement the Account interface in a Java banking system program?

Which one of the following statements is true about dependency in object-oriented programming?

What does the «creates» stereotype indicate in an association relationship?

What is the difference between aggregation and composition in object-oriented programming?

What is the purpose of extending an interface in object-oriented programming?

Which keyword is used to declare a class as final in Java?

Which of the following is NOT a characteristic of interfaces in Java?

What is the purpose of the 'implements' keyword in Java?

What is the correct syntax to implement multiple interfaces in Java?

Which keyword is used to declare a class as abstract in Java?

Can an abstract class have constructors?

What is the purpose of an abstract method in a superclass?

Which of the following statements is true about default methods in Java interfaces?

What is the purpose of extending an interface in object-oriented programming?

What is the difference between aggregation and composition in object-oriented programming?

What is the correct syntax to implement multiple interfaces in Java?

Which one of the following statements is true about the relationship between aggregation and composition in object-oriented programming?

Which one of the following statements is true about inheritance in object-oriented programming?

Which one of the following statements is true about interfaces in Java?

Which one of the following statements is true about the 'extends' and 'implements' keywords in Java?

Which one of the following statements is true about final methods in Java?

What is the purpose of interfaces in Java?

Which of the following is true about default methods in Java interfaces?

What is the purpose of the 'implements' keyword in Java?

Study Notes

Abstract Classes

Interfaces

Class Relationships

Object-Oriented Programming

Keywords

Methods

Inheritance

Interfaces

Studying That Suits You

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