Encapsulation in Java

(Data Hiding + Controlled access)

private variables.
public getter and setter methods.

What is Encapsulation?

• Encapsulation is wrapping data and methods into a single class and restricting direct access using private variables.

why:

• It provides security, data control and better code organisation.

when:

• It is used when data needs protection and controlled access in large applications.

examples:

class Student {

    private int age;     // private variable (hidden)
    private String name;

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

    // Setter
    public void setAge(int age) {
        if(age > 0) {
            this.age = age;
        }
    }

    public String getName() {
        return name;
    }

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

public class Test {
    public static void main(String[] args) {

        Student s = new Student();

        s.setAge(22);
        s.setName("Vishnu");

        System.out.println(s.getName());
        System.out.println(s.getAge());
    }
}

real-time example;

class BankAccount {

    private double balance;

    public void deposit(double amount) {
        if(amount > 0) {
            balance += amount;
            System.out.println("Deposited: " + amount);
        }
    }

    public void withdraw(double amount) {
        if(amount <= balance) {
            balance -= amount;
            System.out.println("Withdrawn: " + amount);
        } else {
            System.out.println("Insufficient balance");
        }
    }

    public double getBalance() {
        return balance;
    }
}

public class Main {
    public static void main(String[] args) {

        BankAccount acc = new BankAccount();

        acc.deposit(5000);
        acc.withdraw(2000);

        System.out.println("Balance: " + acc.getBalance());
    }
}

encapsulation with validation:

class Employee {

    private double salary;

    public void setSalary(double salary) {
        if(salary >= 10000) {
            this.salary = salary;
        } else {
            System.out.println("Salary too low!");
        }
    }

    public double getSalary() {
        return salary;
    }
}