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What is Encapsulation in Java?

What is Encapsulation in Java?
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This blog highlights pertinent details of encapsulation, its importance, and how it works in Java. Encapsulation is a powerful tool that can be used to improve the quality of your Java code. We’ll go through everything from data hiding to the pros and drawbacks of encapsulation. By the end of this post, you’ll have a thorough knowledge of encapsulation and how to apply it in Java projects.

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What is Java Encapsulation and Why it Matters

Encapsulation in Java provides a robust data-hiding mechanism for building reusable and maintainable Java programs. It is a concept in OOP that refers to bundling data and methods that operate on that data within a single unit, such as a class. Encapsulation aims to protect the data from outside interference and provide a controlled interface for accessing and modifying the data.

Encapsulation is achieved through access modifiers, such as public, private, and protected. These modifiers control the visibility of class members (fields and methods) and determine which members can be accessed from outside the class.

Data Encapsulation in Java with Example

Data encapsulation in Java is needed to ensure data integrity and hide implementation details. It allows for controlled access to data through methods, promoting code reusability, modularity, and abstraction.

In Java, data encapsulation is carried out by access modifiers and getter and setter methods.

Let’s see an encapsulation in Java example to see how it works in practice with Java 

public class BankAccount           #simple java class "BankAccount"
    private double balance;         #private instance variable called "balance"
    public double getBalance()   #getter method that returns the value of the "balance"
        return balance;
    public void setBalance(double balance)  #setter method that sets the value of "balance" 
        this.balance = balance;

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Types of Encapsulation in Java

Types of Encapsulation in Java

In Java, encapsulation is achieved using public, private, and protected modifiers.

  • Public – This encapsulation type makes a member available to any class with access to the package.
  • Private – This encapsulation makes a member accessible only within its own class but not outside it.
  • Protected – This encapsulation lets you declare that a method or variable can be accessed by subclasses of your current class and its subclasses only (you cannot use this keyword on methods).
  • Default – The default access modifier for all non-static members is package-private visibility (also known as default).

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Advantages of Encapsulation in Java

Encapsulation allows you to hide the details of your classes by keeping them private and only exposing public methods for other classes to use. This means that if you want to change how something works behind the scenes, you only need to make a small change in one place rather than having multiple places where it needs updating (or even worse – forgetting!).

There are several benefits of encapsulation in Java

  • Data Hiding – The key benefit of encapsulation is that it hides the internal implementation details from the outside world. The inside of the capsule can be changed without breaking the encapsulated functionality.
  • Increased Flexibility –  Since the implementation is hidden, the object can freely change the internals. This allows the object to evolve over time.
  • Reusability – Encapsulated objects can be reused in different applications. They provide well-defined interfaces that can be used to connect various applications.
  • Testing – Encapsulated code is easy to test. You can test the object by calling its public methods and verifying that they work as intended.
  • Maintainability – The encapsulated code is easy to maintain since interacting with the outside world is through a well-defined interface. Any changes made to the internal implementation will not affect the applications using it.

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Use of Encapsulation in Java

Use of Encapsulation in Java

To use encapsulation in Java, you must ensure that only authorized users can access these protected elements. This can be done using access modifiers like public, private, and protected and through visibility modifiers like final (for classes) or static (for methods).

In Java, encapsulation is employed to achieve a wide range of goals.

  • Designing Robust and Maintainable Code – Encapsulation encourages modularity and the separation of concerns, making code easier to comprehend, maintain, and extend.
  • Protecting Sensitive Data – Data hiding prohibits external code from immediately accessing and updating private instance variables, protecting sensitive information.
  • Managing Complexity — Encapsulating data and methods within classes enables engineers to break down complicated systems into smaller, more manageable components.
  • Creating Reusable Components — Making reusable components: Developers can make reusable components by enclosing functionality within self-contained classes.
  • Facilitating Code Evolution – Encapsulation enables changes to a class’s internal implementation without affecting external code, making it easier to adapt and evolve code over time.

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Abstraction Vs. Encapsulation in Java

Abstraction and encapsulation are two important concepts in Java that promote code organization, modularity, and data protection. While they are related, they serve different purposes

PurposeTo simplify the complexity of the system and make it more understandable.To keep the code modular, prevent access to sensitive data, and increase code reusability.
Access LevelPublic, private, protected, and default access levels can be used.Private and protected access levels are commonly used.
ImplementationAchieved through abstract classes and interfaces.Achieved through access modifiers (private, protected, public) and setters/getters.
BenefitsReduces code complexity, increases code reusability, and promotes maintainability.Prevents unauthorized access to sensitive data, increases code reusability, and promotes maintainability.

Abstraction and encapsulation are complementary concepts in Java. Abstraction focuses on providing a simplified view of complex systems, while encapsulation concentrates on bundling related data and behavior and controlling access to them. Both concepts play vital roles in promoting code organization, modularity, and maintainability.

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Data Hiding in Java

Keeping specific parts of your code secret so that other parts cannot access them is known as data hiding. This allows you to change those secret bits without affecting the rest of your program.

Data hiding is an essential notion in object-oriented programming because it enables the development of modular programs that are easier to maintain and extend over time.

The usage of access modifiers in Java allows for data concealment. Access modifiers determine a class, method, or variable’s accessibility. In Java, there are four access modifiers. 

  • Public – Public members can be accessed anywhere within the same class or from other classes.
  • Private – Private members can only be accessed within the same class.
  • Protected – Protected members can only be accessed within the same  class and its subclasses.
  • Default (no modifier) – Default (or package-private) members can only be accessed within the same package.

To achieve data hiding, we usually set instance variables (also known as fields) as ‘private’ so they are not accessible from outside the class. Then, to access and modify these private fields, we can provide public ‘get’ and set methods. These approaches are commonly known as “accessors” and “mutators.”


In a number of ways, encapsulation ascertains businesses to aim for improved security, flexibility, readability, and maintainability of their Java code. This can lead to faster development times, fewer errors, and enhanced security. To conclude, Encapsulation in Java is a potential tool for storing the data members and data methods of a class together.

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About the Author

Senior Consultant Analytics & Data Science

Presenting Sahil Mattoo, a Senior Consultant Analytics & Data Science at Eli Lilly and Company is an accomplished professional with 14 years of experience across data science, analytics, and technical leadership domains, demonstrates a remarkable ability to drive business insights. Sahil holds a Post Graduate Program in Business Analytics and Business Intelligence from Great Lakes Institute of Management.