10+ Obonato Technologies Interview Questions and Answers

Inheritance is a mechanism in C++ that allows a class to inherit properties of another class.

• Inheritance helps in code reusability and saves time and effort in writing code.

• Types of inheritance in C++ are single, multiple, multilevel, hierarchical, and hybrid.

• Single inheritance is when a class inherits from only one base class.

• Multiple inheritance is when a class inherits from more than one base class.

• Multilevel inheritance is when a derived class inherits from a base class, ...read more

The virtual keyword in C++ is used to declare a virtual function, which can be overridden by a derived class.

• Virtual functions allow for dynamic binding and polymorphism

• They are used in inheritance to allow derived classes to provide their own implementation of a function

• Virtual functions are called using a pointer or reference to the base class

• The virtual keyword can also be used to declare a virtual destructor

Method overriding is redefining a method in a subclass with the same name and signature as in the superclass. Method overloading is defining multiple methods with the same name but different parameters in the same class.

• Method overriding is used to provide a specific implementation of a method that is already provided by its superclass.

• Method overloading is used to define multiple methods with the same name but different parameters in the same class.

• Method overriding is runti...read more

Checked exceptions are checked at compile-time while unchecked exceptions are not.

• Checked exceptions are those that are checked at compile-time and must be handled by the programmer using try-catch or throws clause.

• Unchecked exceptions are those that are not checked at compile-time and can occur at runtime. They do not need to be handled explicitly.

• Examples of checked exceptions include IOException, ClassNotFoundException, and SQLException.

• Examples of unchecked exceptions inc...read more

Abstract class can have implementation while interface cannot. A class can implement multiple interfaces but only extend one abstract class.

• Abstract class can have constructors while interface cannot

• Abstract class can have non-abstract methods while interface can only have abstract methods

• Interfaces are used to achieve multiple inheritance in Java

• Abstract classes are used to provide a base for subclasses to extend and implement

• Example of abstract class: Animal with abstract m...read more

Principles of OOPs include encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: bundling data and methods that operate on that data within a single unit.

• Inheritance: creating new classes from existing ones, inheriting properties and methods.

• Polymorphism: ability of objects to take on multiple forms, allowing for flexibility in programming.

• Abstraction: hiding implementation details and only showing essential features to users.

A functional interface is an interface that contains only one abstract method.

• Functional interfaces are used in Java 8's lambda expressions and method references.

• They can also have default methods and static methods.

• Examples of functional interfaces include Runnable, Comparator, and Callable.

An exception is an event that interrupts the normal flow of a program's execution.

• Exceptions are used to handle errors and unexpected situations in a program.

• They can be caused by a variety of factors, such as invalid input, hardware failures, or network issues.

• Examples of exceptions include NullPointerException, ArrayIndexOutOfBoundsException, and IOException.

• Exception handling involves catching and handling exceptions in a way that allows the program to continue running.

• If ...read more

Map interface is a part of Java Collections Framework that maps unique keys to values.

• It provides methods to add, remove, and retrieve elements based on their keys.

• It does not allow duplicate keys.

• It can be implemented by HashMap, TreeMap, and LinkedHashMap classes.

• Example: Map map = new HashMap<>();

• map.put("John", 25);

• int age = map.get("John"); // age = 25

An interface is a contract between two systems or components that defines the methods and properties that can be used to communicate with each other.

• An interface defines a set of methods and properties that a class must implement.

• Interfaces allow for polymorphism, where objects of different classes can be treated as if they are of the same type.

• Interfaces can be used to define callbacks or event handlers.

• Examples of interfaces in programming languages include Java's Runnable ...read more