Interview questions 2

Question 1

What is a data structure?

Answer 1

A storage format that defines the way data is stored, organized, and manipulated.

Question 2

What is an array?

Answer 2

Collection of items of the same type in contiguous memory locations.

Question 3

What is a linked list?

Answer 3

A linear data structure in which elements are not necessarily stored contiguously. Sequence of nodes, each one pointing to the next in a chain-like structure.

Question 4

What is a binary tree?

Answer 4

An extension of the linked list where each node has at most 2 children.

Question 5

What is recursion?

Answer 5

A function calling itself based on a terminating condition.

Question 6

What is OOP?

Answer 6

A paradigm that provides concepts such as objects, classes, and inheritance.

Question 7

What is an object in OOP?

Answer 7

A real-world entity that has a particular state and behavior. It is an instance of a class.

Question 8

What is a class in OOP?

Answer 8

A logical entity that defines the blueprint from which an object can be created or instantiated.

Question 9

What is inheritance & its benefits?

Answer 9

An object gaining all the properties & behaviors of a parent object. Provides code reusability.

Question 10

What is polymorphism?

Answer 10

A concept that allows a variable, function, or object to take on multiple forms. This happens when many classes are related to each other by inheritance.

Question 11

Inheritance vs polymorphism.

Answer 11

While inheritance allows us to inherit attributes & methods from another class, polymorphism uses those methods to perform different tasks.

Question 12

Example of polymorphism.

Answer 12

class Animal
public void animalSound()
System.out.println(“The animal makes a sound”);

class Pig extends Animal
public void animalSound() {
System.out.println(“The pig says: wee wee”);

class Dog extends Animal
public void animalSound() {
System.out.println(“The dog says: bow wow”);

Question 13

What is overloading?

Answer 13

Method Overloading allows different methods to have the same name, but different signatures where the signature can differ by the number of input parameters or type of input parameters, or a mixture of both.

Question 14

What is overriding?

Answer 14

Same method (with same parameters & type) exists in a child & parent class. The child is given priority.

Question 15

What is an abstract class?

Answer 15

A class you cannot instantiate.

Question 16

What is an interface?

Answer 16

Specifies the behavior of a class.

Question 17

What is a DLL?

Answer 17

Special type of LL in which traversal across the data elements can be done in both directions. 2 links per node - one that goes to the next node and one to the node before it.

Question 18

What is a deque?

Answer 18

Double-ended queue. Elements can be inserted or removed from either end.

Question 19

How does variable declaration affect memory?

Answer 19

The amount of memory that will be reserved or allocated depends on the data type being stored in that variable.

Question 20

What are dynamic data structures?

Answer 20

Expand & contract as a program runs. Provides very flexible method of data manipulation.

Question 21

What is cohesion vs coupling?

Answer 21

Coupling describes the relationships between modules, and cohesion describes the relationships within them.

Question 22

Benefits of cohesion.

Answer 22

Increased module reusability

Question 23

When method overloading exists, does the parent or child get higher priority?

Answer 23

Child

Question 24

Purpose of an abstract class.

Answer 24

To create a template for future classes. Abstract classes/methods are generally used when a class provides some high level functionality but leaves out certain details to be implemented by derived classes.

Question 25

What does it mean for a class to implement an interface.

Answer 25

When a class implements an interface, it is agreeing to perform the specific behaviors of the interface.

Question 26

What does it mean to extend an interface.

Answer 26

The child interface inherits the methods of the parent interface.

Question 27

What properties does an interface have (vs a class)?

Answer 27

Cannot be instantiated, has no constructors, all its methods are abstract, all fields must be declared static & final.

Question 28

What does an interface do, allow, and why is it beneficial?

Answer 28

Increases abstraction by specifying only the method signature and not its implementation. Also allows for multiple inheritance. Last, while using an interface, we define the method separately and the signature separately. This way, all the methods, and classes are entirely independent and archives Loose Coupling.