Encapsulation in Java.

Encapsulation Kya Hai?

Encapsulation ka matlab hota hai – data ko ek single unit mein bundle karna aur unauthorized access se bachana.

Real-life example: Tumhare bank account ka PIN sirf tumhe pata hai – ye hi encapsulation hai. Data hide kiya gaya hai.

Java mein encapsulation tab achieve hota hai jab:

• Variables private hote hain
• Unhe access karne ke liye public getters and setters use hote hain

Example – Encapsulation in Action

class Student {
    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) {
            this.age = age;
        }
    }
}

class Main {
    public static void main(String[] args) {
        Student s = new Student();
        s.setName("Shakib");
        s.setAge(20);

        System.out.println(s.getName()); // Shakib
        System.out.println(s.getAge());  // 20
    }
}

Key Points:

• Variable direct access nahi hote
• Data ko modify karne ke liye method call karni padti hai
• Aise access control se hum logic bhi add kar sakte hain (jaise age > 0)

Access Modifiers in Java

Java mein 4 tarah ke access modifiers hote hain:

1. private – Sirf same class ke andar access
2. default – Same package ke andar access (agar koi modifier nahi lagate)
3. protected – Same package + child classes
4. public – Har jagah access

Benefits of Encapsulation

• Data hiding – sensitive data ko secure banata hai
• Control over data – getter/setter se validation add kar sakte ho
• Reusability – ek baar class bana lo, baar-baar use kar sakte ho
• Maintainability – changes karna easy hota hai, kyunki implementation hidden hota hai

Summary

• Encapsulation = data + methods bundled together
• Variables ko private rakhna chahiye
• public getters/setters se access aur control dena chahiye
• Isse code zyada secure, readable, and manageable banta hai