BookmeNow - core java concepts

What s abstraction?

Abstraction is a process of hiding the implementation details from the user.
Only the functionality will be provided to the user. In other words, the user will have the information on what the object does instead of how it does it.

Abstract classes & Methods:

Abstract classes are always declared by abstract keyword.
It can have both abstract method (mtd without body) as well as non-abstract methods

Note: Abstraction classes achieve partial abstraction.
Interfaces on the other hand are used for 100% abstraction.

eg: Parent class contains the rule, and all child classes inherit parent class and use the methods in the parent class as a reference to build their own configurations.

If there is any method in the class which is abstract, then the class will be treated as abstract.

Every abstract class is created to implement and we use extends keyword to implement it.

Interface

Their is only signature and no code is present in an interface.

implements vs extends ??

Inheritance is reusing the previously written methods in other class

extents word is used to inherited the properties,
multiple inheritance is not possible in java

Function Overloading

If the same class have multiple methods with the same name is called as function overloading, they differ with arguments.

Rule

they differ with arguments
For using overloading either argument count or argument return type must be different

Function Overriding

If the parent and child class have the same methods with the same name is called as function overiding, it is only possible if they have same arguments.

Rule

preference is given to local method

Array : A container which stores multiple values of the same data type.

Multidimensional Array

Index starts from zero

so here 2-third row and 1-second column

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