Java Encapsulation

Encapsulation is an OOP concept that wraps data (variables) and methods together in a class and restricts direct access to some of the object’s components.

It is also known as data hiding.

1. Key Features of Encapsulation

Private variables – Restrict access from outside the class.
Public getter and setter methods – Provide controlled access to variables.
Enhances security and maintainability.
Helps in flexible implementation and code modularity.

2. Syntax of Encapsulation

class ClassName {
private DataType variable; // private variable// Getter method
public DataType getVariable() {
return variable;
}

// Setter method
public void setVariable(DataType variable) {
this.variable = variable;
}
}

class ClassName {

private DataType variable; // private variable// Getter method

public DataType getVariable() {

return variable;

}

// Setter method

public void setVariable(DataType variable) {

this.variable = variable;

}

3. Example: Encapsulation in Java

class Person {
private String name; // private variable
private int age;// Getter for name
public String getName() {
return name;
}

// Setter for name
public void setName(String name) {
this.name = name;
}

// Getter for age
public int getAge() {
return age;
}

// Setter for age
public void setAge(int age) {
if(age > 0) { // validation
this.age = age;
} else {
System.out.println("Invalid age!");
}
}
}

public class Main {
public static void main(String[] args) {
Person p = new Person();

p.setName("Alice"); // using setter
p.setAge(25); // using setter

System.out.println("Name: " + p.getName()); // using getter
System.out.println("Age: " + p.getAge());
}
}

class Person {

private String name; // private variable

private int age;// Getter for name

public String getName() {

return name;

}

// Setter for name

public void setName(String name) {

this.name = name;

}

// Getter for age

public int getAge() {

return age;

}

// Setter for age

public void setAge(int age) {

if(age > 0) { // validation

this.age = age;

} else {

System.out.println("Invalid age!");

}

public class Main {

public static void main(String[] args) {

Person p = new Person();

p.setName("Alice"); // using setter

p.setAge(25); // using setter

System.out.println("Name: " + p.getName()); // using getter

System.out.println("Age: " + p.getAge());

}

📌 Output:

Direct access to name and age is not allowed because they are private. Access is only through getter and setter methods.

4. Advantages of Encapsulation

Data Hiding – Prevents unauthorized access.
Improved Security – Sensitive data cannot be modified directly.
Code Flexibility – You can change the internal implementation without affecting outside code.
Validation – Can validate inputs in setter methods.
Better Maintainability – Keeps code modular and organized.

5. Key Points

Feature	Description
Private variables	Cannot be accessed directly from outside class
Public getter/setter	Used to read/write private variables
Validation	Can restrict invalid data using setters
OOP Principle	Encapsulation is part of Abstraction and Data Hiding

Java Encapsulation