OOP studying

Question 1

What is OOP?

Answer 1

Programming paradigm that relies on the concept of classes and objects. It is used to structure a software program into simple, reusable pieces of code.

Question 2

What is a class?

Answer 2

Blueprint of an object. User defined data type and can also encapsulate functions. Stored in heap memory/dynamic memory.

Question 3

What is an object?

Answer 3

Instance of a class. An attribute or characteristic.

Question 4

What is Encapsulation?

Answer 4

Methods/functions and variables in a class. Makes code look cleaner. Example – Element ID associated to buttons on the android app. Swipe functionality.

Question 5

What is Inheritance

Answer 5

Allows classes to inherit features of other classes. Supports reusability. We inherit certain properties from the class ‘Human’ such as the ability to speak, breathe, eat, drink, etc

Question 6

What is Abstraction?

Answer 6

Hiding the implantation details. Example – Header files. ATM.

Question 7

What is Polymorphism?

Answer 7

Same function or object behaves differently in different scenarios. Example – Dogs are used to herd sheep but not all dogs herd sheep.

Question 8

What is Function/Method overloading?

Answer 8

Two or more functions with same name but different parameters

Question 9

What is Function/Method overriding?

Answer 9

Creating a new version of an old function in the child class

Question 10

What is Data hiding?

Answer 10

Put data in a class and declare it as private. Prevents honest mistakes.

Question 11

What are pointers?

Answer 11

Is a variable that stores a memory address

Question 12

What is a reference variable?

Answer 12

Is an address that indicates where an object’s variables and methods are stored

Question 13

What is a linked list?

Answer 13

is a linear collection of data elements. Each element points to the next

Question 14

What are access specifiers?

Answer 14

Public – accessible from outside the class
Private – accessible from other members of the same class

Question 15

What is an inline function?

Answer 15

Actual code is in the function

Question 16

“this” pointer

Answer 16

refers to the current object of a class

Question 17

What is a structure?

Answer 17

Also a user defined data type. Stored in stack memory.

Question 18

What is a constructor?

Answer 18

A special construct that creates objects. no return type. same name as class.

Question 19

What is a default constructor?

Answer 19

A constructor with no parameters.

Question 20

What is a Parameterized constructor?

Answer 20

Constructor with parameters

Question 21

What is a copy constructor?

Answer 21

Creates a new object as a copy of an existing object

Question 22

What is a destructor?

Answer 22

Happens automatically when an object is removed. Same name as the class. “~” tilde

Question 23

Memory allocation

Answer 23

“New” is used for memory allocation

“delete” is used for memory deallocation

Question 24

What is Multi-threading?

Answer 24

Multiple threads are executed simultaneously. Each thread starts its own stack based on the flow (or) priority of the threads.

Question 25

What is a Thread?

Answer 25

the flow of execution is called Thread. Every java program has at least one thread called the main thread

Question 26

How is Java different from C++?

Answer 26

C++ allows users to use pointers in the program.

Question 27

What is the main objective of garbage collection?

Answer 27

is to free up the memory space occupied by the unnecessary and unreachable objects during the Java program execution by deleting those unreachable objects.

Question 28

Disadvantages of a Multithreaded Application

Answer 28

Difficulty of debugging

It is much harder to replicate an error in a multithreaded application than it is to do so in a single-threaded