(Based on your video content)

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🚀 Introduction

In Object-Oriented Programming (OOP), one of the most important concepts is:

👉 Encapsulation

Encapsulation helps you:

• Protect your data
• Control access to variables
• Write safer and more reliable code

In this article, we will understand encapsulation with simple examples and practical code.

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❌ The Problem: Direct Access to Data

In earlier programs, we used code like:

s1.name = "Alice";
s1.age = 20;

👉 This means:

• Anyone can directly change your data
• No control over values

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🚨 What Can Go Wrong?

s1.marks = -500;

👉 This is invalid data, but Java allows it if variables are public.

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⚠️ Issues with Public Variables

• No validation
• Anyone can modify data
• Data becomes unsafe
• Bugs become hard to trace
• Security is compromised

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✅ Solution: Encapsulation

👉 Encapsulation means:

• Wrapping data + methods into one unit
• Restricting direct access to data
• Allowing access only through controlled methods

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🧠 Definition

Encapsulation is:

👉 Data hiding + controlled access

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🔐 Step 1: Make Variables Private

class Student {
    private String name;
    private int age;
    private int marks;
}

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💡 What Happens?

• Variables are hidden
• Cannot be accessed directly

s1.marks = 90; // ❌ ERROR

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🔑 Step 2: Use Getters and Setters

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🧩 What are Getters?

• Used to read data

public int getMarks() {
    return marks;
}

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🧩 What are Setters?

• Used to update data

public void setMarks(int m) {
    marks = m;
}

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🔍 Adding Validation (Very Important)

public void setMarks(int m) {
    if (m >= 0 && m <= 100) {
        marks = m;
    }
}

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💡 Why This Matters?

• Prevents invalid values
• Protects object data

👉 Example:

s1.setMarks(-500); // ❌ Ignored
s1.setMarks(80);   // ✔️ Accepted

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🏗️ Complete Example

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📘 Student Class

class Student {
    private String name;
    private int age;
    private int marks;    // Setter Methods
    public void setName(String n) {
        name = n;
    }    public void setAge(int a) {
        age = a;
    }    public void setMarks(int m) {
        if (m >= 0 && m <= 100) {
            marks = m;
        }
    }    // Getter Methods
    public String getName() {
        return name;
    }    public int getAge() {
        return age;
    }    public int getMarks() {
        return marks;
    }
}

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🖥️ Main Class

class Main {
    public static void main(String[] args) {        Student s1 = new Student();        s1.setName("Ajay");
        s1.setAge(25);
        s1.setMarks(80);        System.out.println(s1.getMarks());
    }
}

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🖨️ Output

80

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🔁 Before vs After Encapsulation

Without Encapsulation	With Encapsulation
Direct access ❌	Controlled access ✔️
No validation ❌	Validation ✔️
Unsafe data ❌	Safe data ✔️
Hard to debug ❌	Easy to manage ✔️

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⚠️ Common Mistakes

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❌ No Validation in Setter

public void setMarks(int m) {
    marks = m; // ❌ unsafe
}

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❌ Making Variables Public

public int marks; // ❌ wrong approach

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❌ Changing Data Directly

s1.marks = -10; // ❌ not allowed

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🔥 Key Takeaways

• Encapsulation = Data hiding + controlled access
• Use private variables
• Use getters and setters
• Always validate input
• Prevent invalid data

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🧠 Final Insight

👉 Without encapsulation:

• Data = unsafe ❌

👉 With encapsulation:

• Data = protected, controlled, reliable ✅