LLD basics— [Notes]

[Refer LLD Index for all LLD topics]

· Sequential vs Procedural languages
· OOP | Procedural vs Object Oriented languages
∘ Method vs Functional Procedure
∘ Fields + Methods?
∘ State
∘ Polymorphism
· TODO

Sequential vs Procedural languages

• Sequential languages executes code line by line
• Procedural languages are Sequential languages that support procedures/functions

OOP | Procedural vs Object Oriented languages

source — https://m.facebook.com/Studytonight/photos/pcb.2729007120531357/2729007027198033/?type=3&source=48&locale2=pl_PL&__tn__=EH-R

//Procedural 
int main(){
  String animal_name = "Zebra";
  int animal_id = 123;
  String animal_sound = "bow"
  System.out.println(animal_name);
  System.out.println(animal_id);
  System.out.println(animal_sound);
}

Class : represents a real work entity.

//OOP

class Animal {
  String name;  // fields/attributes/properties
  int id;
  String sound;

  public Animal(String name, int id, String sound){
    this.name = name;
    this.id = id;
    this.sound = sound;
  }

  public String getName(){   // behaviours
    return this.sound;  
  }
}

int main(){
  Animal zerba = new Animal("zebra", 123, "bow");  //object
  
}

Method vs Functional Procedure

• Method is basically the function in the context of a class
• for java [object oriented language]— methods and procedure can be same.

Fields + Methods?

• Fields + Methods are known as Members of a class

State

• The value of every field of a class at a particular time is known as the state of the class

Favor interfaces >> Inheritance

Polymorphism

• When we can assign an object of child class to parent class

TODO

• why web apps does not have main method?
• Procedural vs Functional languages
• Object Oriented vs Functional languages