OOP

Question 1

What does a getter do?

Answer 1

It gets the value attributes of a class

Question 2

What does a setter do?

Answer 2

It sets the value of a class

Question 3

What does a constructor do?

Answer 3

It forces attributes on creation of an object of the class.

(method that is ran when an object is instantiated)

Question 4

What is method overloading?

Answer 4

Same method but different parameter or data type

Question 5

What is constructor overloading?

Answer 5

Normal overloading but with multiple contstructors instead of methods.

Question 6

What is method overriding

Answer 6

It is basically updating an already existing function

Question 7

How to use inheritance in Java?

Answer 7

Public class Lowerclass extends Superclass

and
in constructor
super(variable name)

Question 8

What does adding abstact to a class do?

Answer 8

1. The class cannot be instantiated( meaning you cant make an object from the class, but they can have sub classes which you can instantiate ( make an object)

Polymorphism

Question 9

What does adding abstract to a method do?

Answer 9

It means that the method doesnt have a body (no code)
So you must use it in a subclass.

Question 10

What is the difference between a singly, doubly and circularly linked list.

Answer 10

Singly: normal
Doubly: has next and previous
Circularly: The tail is connected to the head (the tail points to the head.

Question 11

How to overload methods?

Answer 11

Same method name but different data type or different no. of parameters

Question 12

How to override methods?

Answer 12

You type @Override
then give the method in the sub class new code.

Question 13

What does super keyword do?

Answer 13

Super refers to the subclass’s super class (similar to .this)

attributes:
super(values to be passed from the superclass);
this.value in the sub class
methods:
super.methodname();

Question 14

How to use encapsulation?

Answer 14

Use getter and setter

Question 15

How to code encapsulation?

Answer 15

When creating the object from the class, you have to use the getter and setter methods instead of objectName.variableName

The constructor will also use the setter to give values.

Use private and protected

Question 16

What is polymorphism

Answer 16

Basically method overiding or overloading (u can use both) with multiple different classes that inherit from the same superclass.

Question 17

How to do exceptions?

Answer 17

Try = Code to test
Catch = Code to run if theres an error

catch(Exception e) {}

(add more types of catch exceptions for different type of errors or just put exception)
Finally = Code to run after the try and catch
Throw new = Makes an error happen (you have to give the error type)

Question 18

What is an Array

Answer 18

An array is a data structure, which can store a fixed-size collection of elements of the same data type.

Question 19

What is the syntax in Java for creating a 2D array?

Answer 19

int [ ] [ ] arrayName = new int [ 3 ] [ 3 ];

OR

int [ ] [ ] arrayName =
{

{1,2,3},
{4,5,6},
{7,8,9}

};

Question 19

How to traverse in 2D arrays in Java

Answer 19

for ( int i = 0; i < arrayName.length; i++) {

for (int j = 0; j < arrayName[i].length; i++) {

System.out.println(arrayName[ i ] [ j ]

Question 19

What is a 2D array?

Answer 19

A 2D array is an array of arrays, where each element is itself an array. It is a collection of
elements arranged in rows and columns.

Question 20

What are 2 uses of 2D arrays?

Answer 20

2D arrays are useful for representing matrices or grids.

Question 20

What is a linked list?

Answer 20

A linked list is a linear data structure where elements are not stored contiguously in memory.
Instead, each element (node) contains a value and a reference to the next node in the
sequence.

Question 20

What are the 3 types of linked lists?

Answer 20

singly linked, doubly linked, and circular linked lists.

Question 20

What are the main methods for linked lists?

Answer 20

insert, delete, display. delete, replace, inserting at a given position

Question 20

What are stacks?

Answer 20

A stack is a linear data structure that follows the Last-In-First-Out (LIFO) principle Stacks can be implemented using arrays or linked lists.

Question 20

What are 4 uses of stacks

Answer 20

Stacks are used in various applications, such as expression evaluation, backtracking algorithms, and undo/redo operations.

Question 21

What are the main methods used for stacks?

Answer 21

Push, pop, is Empty, peek, size

Question 21

What are Queues?

Answer 21

A queue is a data structure that follows the First In, First Out (FIFO) principle. It's similar to standing in a line or queue at a store, where the first person to join the line is the first to be served.

Question 22

What are 3 uses of queues?

Answer 22

Queues are commonly used in various computer algorithms and applications, such as job scheduling, task management, and breadth-first search algorithms.

Question 22

What are the 4 types of queues?

Answer 22

Linear Queue, Circular Queue, Priority Queue and Delay Queue.

Question 23

What is a Linear Queue?

Answer 23

In a linear queue, elements are arranged in a linear or sequential manner. It follows the FIFO (First In, First Out) principle, where elements are inserted at one end (rear) and removed from the other end (front).

Question 24

What is a Circular Queue?

Answer 24

Circular queues are similar to linear queues, but they wrap around when reaching the end of the underlying array or buffer. This allows efficient use of space and prevents wastage. Circular queues have a fixed size and offer better performance for certain applications like buffering in I/O operations.

Question 25

What is a Priority Queue?

Answer 25

Priority queues are a type of queue where each element has an associated priority. Elements with higher priority are dequeued before those with lower priority, regardless of the order they were added. Priority queues are commonly used in algorithms like Dijkstra's shortest path algorithm and in scheduling tasks.

Question 26

What is a Delay Queue?

Answer 26

A delay queue holds elements until a certain delay has elapsed before allowing them to be dequeued. Elements are ordered based on their delay duration.

Question 27

What is Encapsulation?

Answer 27

Encapsulation helps in achieving data hiding and protects the integrity of the data by preventing direct access from outside the class | Security

Question 28

What is Abstraction

Answer 28

Abstraction is like using a TV remote without knowing how it works internally. It allows you to focus on what an object does, rather than how it does it. You deal with the essential characteristics of an object, ignoring the unnecessary details. Abstraction, on the other hand, focuses on hiding the implementation details of an object and emphasizing only the essential features or behaviors relevant to the interaction with the object. It allows us to work with high-level concepts without worrying about the low-level details of how those concepts are implemented. | encapsulation sets boundaries and controls access to the inner workings

Question 29

What is Inheritance?

Answer 29

Inheritance is like passing down traits from parents to children. It allows a new class to inherit properties and behaviors from an existing class, promoting code reusability and facilitating hierarchical relationships.

Question 30

What is Runtime Polymorphism

Answer 30

Method overriding

Question 31

What is