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Class and object in java

Objects:

By now you might have understood the basic concept of Object Oriented Programming. Now let us talk about what exactly Objects are:

Objects can be defined as a unique entity which contains data and functions (characteristics and behavior) together in an Object Oriented Programming (OOP) Language.

Let us consider any real-world object: Suppose a Chair

Characteristics:

  • It has four legs.
  • It has two armrests.
  • It has a seat, which may be plain or foamed.
  • It comes in various colors.

Behaviors:

  • It is used to sit.
  • It can be used to move 180° while sitting in the same place.

These characteristics and behaviors of a real-world object are equivalent to the data members of a Software world object.

Suppose if we are creating a database of all the residents of India: Then the data members of an Indian would be:

  • Name
  • Address
  • Date of Birth
  • Aadhar Number, PAN Card Number, Passport Number
  • Blood Group, Biometrics and Genetics Information

These may be the data members of the Software Object ‘Indian’.  The functions of the Object can be:

  • To accept data:  acceptdata() where values of the data members are accepted.
  • To search for data in the database:  searchdata().
  • To display the data members of any individual:  display()

Classes:

A class is defined as the set of similar objects. Each object of a class possesses the same attributes and common behavior defined within the same class.

This may sound a bit of technical and complex.

So, let’s understand this in a simpler way:

Let us take the example of a car showroom:

A car showroom has various kinds of cars: high-end luxuries like Mercedes, Lamborghini, BMW, etc. , affordable SUVs like Renault, Scorpio, or small budget cars like i10, Alto, Kwid, etc.

Here each car has at least one common feature: It can be driven for transportation. Some may run on Petrol and others on Diesel.

Each car might have some features that are exclusive in it.

Also each car has a Vehicle No., Chassis No., Model Name, Size Color, etc.

So we can consider Car Showroom as a collection of cars.

If we represent this in a computer: The Car Showroom is a class, similar objects are the cars where each car has similar features and some exclusive features. These cars have same attributes: Model Name, Chassis No., etc (though the values are different) and a common behavior: Transportation.

Compare this with the definition of class, hope this is clear!!

Java thus is not only an object-oriented programming language but has many features similar to C++ as well.

It was originally created so that Internet applets can be executed and downloaded while Web Browsing but has rapidly experienced a surge in wide acceptance among the users as a programming language.

Class and object in java