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Encapsulation is one of the four fundamental object-oriented programming/OOP concepts. These four fundamental OOP concepts are encapsulation, inheritance, abstraction, and polymorphism. This article focuses on encapsulation in the context of Java.
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In this article, we’ll learn:
Encapsulation in Java refers to wrapping the data, variables, methods acting on the data, and code together into a single unit. Encapsulation hides the class variables from other classes. These class variables can be accessed only through the methods of their current class, leading to data hiding.
To create a fully encapsulated class in Java, we need to make all the data members of the class private. We then use setter methods to set and getter methods to get the data in the class. An example of a fully encapsulated class is the Java Bean class.
Recommended Reading: Overriding in Java
To achieve data encapsulation in Java, we need to:
Some of the advantages of using encapsulation in Java include:
Let’s look at some examples to understand the concept of encapsulation in Java better.
The class below has all the data members as private, making it a fully encapsulated class. We also have getter and setter methods for reading and writing:
Using the fullyEncapsulated class (stored with the file name fullyEncapsulated.java) in the following manner:
The following is an example of a read-only class. It only has the getter method, no setter method. Here, we can only read, not modify the data member values or properties of the class:
The following is an example of a write-only class. It only has the setter method, no getter method. Here, we can only modify, not access, or read the data member values or properties of the class:
Abstraction is the mechanism of hiding unnecessary information to avoid misuse of code, highly coupled code, and confusion leading to more errors.
Encapsulation is the mechanism of hiding data in a single entity/unit with a method that protects the information from the outside, even when giving get/set access.
Abstract classes are implemented using abstract class and interfaces, while encapsulation involves using access modifiers like private along with getter and setter methods to be done.
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Q1. How can the concept of encapsulation be achieved in a program?
To achieve data encapsulation in Java, we need to declare the class variables as private using access specifiers. We also need to create public setter and getter methods for modifying and viewing the variable values, respectively.
Q2. Which access modifier is used for encapsulation in Java?
The access modifier “private” is used for encapsulation in Java.
Q3. Why is encapsulation important in Java?
Encapsulation hides implementation details from the clients, giving them just the smooth experience they need. It hides data that is irrelevant to other classes, making it less likely for them to misuse it and cause confusion/errors. It provides more control over the code, coupling, and decision involving which behavior to expose.
Q4. What are the benefits of encapsulation in Java?
Data hiding, easy unit testing, quick and easy to create using IDEs, making the class fields or the entire class read-only or write-only, and increasing control over code are some of the advantages of encapsulation in Java.
Q5. Are encapsulation and data hiding the same?
No. In data hiding, the data can only be defined as private, whereas the data can be public or private in data encapsulation. Encapsulation is a sub-process in data hiding. And data hiding is a process and technique both in itself.
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