OOPs Concepts in Java: Basics, Characteristics and its Examples

What is OOPS in Java?

OOPs (Object-Oriented Programming System) is a programming concept, methodology, or paradigm, that is a core of Java programming used to design programming using classes and objects. The OOPs concepts in Java build on the four main principles,

- Encapsulation: Binds data and operations that work on data together in a construct.

- Abstraction: A process that displays only essential information.

- Inheritance: Defines relationships among classes.

- Polymorphism: Utilisation of a function in multiple forms. Poly means 'many', and morphism means 'forms'.

And, rely on the other three concepts of Association, Aggregation, and, Composition.

 

Suggested Read: OOPs Interview Questions And Answers

 

Basic OOPs Concepts with Examples

The basic Java OOPs concepts in general includes,

1) Class

The class is the first basic OOPs concepts, which is a group of the same entities. Class is a logical component and not a physical entity. 

For example:

If there is a class as ‘branded shoes’, the objects can be Burberry, Stuart Weitzman, Louis Vuitton, Gucci, and more. The properties or data of the class can be brands, unique pieces, or prices of these shoes.

The methods that may be performed with these shoes are global size standards, unique materials or features, comfort, signature, and style.

2) Objects

An object is a real-work thing, a basic unit of object-oriented programming that can be physical or conceptual.

In other words, an object in object-oriented programming is defined as an instance of a class that can be physical or conceptual. 

Likewise, an object in Java OOPs concepts has a state and behavior with the information and function that operates on the data.

For example; Let’s consider conceptual and physical objects such as bikes (physical) and institutes (conceptual). Other examples include tables, chairs, glass, trucks, cars, engines, and more.

An object mainly consists of: 

- State
- Behavior
- Identity
- Method

3) Inheritance

Inheritance is another of the basic OOPs concepts in Java and the most powerful feature in which one class shares structure and behavior defined in one or more classes. The medium of obtaining a new class from an old class is defined as inheritance or derivation.

It is the relationship among the classes. The old class is known as the base class and the new class as the subclass (derived).

Let us consider an OOPs example; a family of four members having a father, mother, son and daughter. The father and mother (parents) were taken as the base class and the son and daughter (children) as a subclass.

The subclasses (children) will often inherit features derived from both the base class (parents) with better versions of inheritance.

Similarly OOPs, with the use of effective inheritance, can reduce errors and time-saving in programming giving quality work and productivity.

Take another example; Java and C# are OOPs languages that do not support multiple inheritances through classes.

4) Polymorphism

Poly is a Greek term that means 'many', and morphism means 'forms'. Polymorphism is another OOPs concepts that have the ability of a variable, object, or function to take more than one form. Polymorphism is also the capability to use a function in many forms. This means that the same operator behaves differently in varying scenarios.

 

Take an OOPs example; The class animal or human cannot have the same behavior. Similarly, an entity, function, or object behaves differently as per the scenarios. Overloading and overriding are examples of OOPs.

5) Abstraction

Abstraction is an activity that displays only the essential information and excludes unnecessary information.

A technique for data hiding that selects data from multiple data sources to display only required information. The motive is to minimize programming complexity and effort.

For example; for operating a television, a user need not focus on internal operations. They have to pay attention to the remote control, screen display, switch and cable connection, and others.

6) Encapsulation

Encapsulation is the first pillar or principle of object-oriented programming. A process of binding data (properties, variables) and operations or functions (methods) that works on data together in a single construct. A class can be the best example of encapsulation.

For example; Consider going to the salon, only the stylist has the experience and the options based on your requirements.

7) Association

The relationship between two separate classes with the help of objects is called association. A basic concept in Java describes the connection between two or more objects.

For example; let us take a connection between the airplane and the passengers. Many passengers associate with one airline, while, a single passenger associates with multiple airlines. Likewise, multiple passengers connect with multiple airlines, and a single passenger with one airline.

8) Aggregation

Aggregation is the technique where objects have their separate lifecycle, it represents a special connection between an object containing other objects. 

When an object ‘has a’ another object, then, you have got an aggregation in between them. This is also called a ‘has a’ relationship. For an OOPs example; an employee can be only in one department. Even if the department is deleted, the employee exists. This is called ‘has a’ relationship.

9) Composition

Composition is one of the fundamental aspects of object-oriented programming that is a special case of aggregation.

It outlines a class that cites one or more objects of the other class occurrence variables. In both aggregation and composition, a direction to specify is a must as the object contains the other object.

When an object carries another object, if the contained object is incapable to exist without the existence of the container object, it is defined as composition.

For example; if item 2 is created from item 1, then, item 1 has the power to delete item 2. Unlike aggregation, object 2 cannot exist without object 1.

 

Characteristics of OOPs Concepts

The main characteristics of OOPs concepts are as follows:

- A method that implements in which programs classify as cooperative collections of objects.
- The object's state is set by the value of its properties whereas the behavior is by the operation it gives.
- Major importance on data rather than procedural process.
- Programs are divided into entities defined as objects.
- Data structures are storage that is used to characterize objects.
- Data is safeguarded so that it is not accessible by external functions
- Functions that operate on data of an object bind together in data structures.
- Objects communicate with each other by sending and receiving information through functions.
- Easy addition of new data and functions whenever mandatory.
- It follows a bottom-up design approach in program design.

 

Benefits of OOPs Concepts

The best advantages of OOPs concepts include;

- Provides modularity and enhances program for easier troubleshooting as objects exist independently
- Real world programming
- Code reusability through inheritance
- OOPs concepts designed with lesser limitations for larger programs are hard to write.
- Enhances easier and clear modular structure for programs.
- Flexibility through polymorphism
- Effective problem solving and better software quality
- Lower maintenance cost & resilience to change and hides information
- Flexibility of upgrading systems of any size
- Improvise the creation of Graphical User Interface (GUI) applications
- Faster goals achieved for programmers
- Greater programmer productivity & data become active
- Faster, accurate, better written applications compared to a procedural program
- Simple to develop and implement
- Much easier communication with the message passing capability

 

 

Takeaway

Programmers around the world count on OOPs concepts as it is easy to divide tasks for the same projects. Why not? The best part is that software becomes simple to handle unlike the traditional system of approach with flaws. An Object-Oriented System can effortlessly upgrade from a small system to a large system. Doubtlessly, programs are tightened to secure and cannot be invaded by other applications or systems.

No wonder with all the advancements in the expanding digital era, the relevancy of an object-oriented system to build programs from standard working modules makes communications easier saving time and higher productivity.

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