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🌟 Introduction

To truly understand Object-Oriented Programming (OOPs) in Java, students must go beyond small examples and work on slightly detailed, real-world-like problems 💡

👉 This practical file includes 10 well-structured programs:

• 🟢 4 Easy (but meaningful)
• 🟡 3 Medium (concept-building)
• 🔴 3 Hard (real-world application)

Each question is designed to:

• Improve logic 🧠
• Strengthen OOP concepts 💪
• Prepare for viva & exams 🎯

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📌 Instructions for Students

• ✍️ Write full program (class + methods + main)
• 🧠 Understand logic before coding
• 📝 Add comments
• ▶️ Test with multiple inputs

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🟢 EASY LEVEL (Detailed Fundamentals)

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🧪 Program 1: Student Management System

📌 Question

Create a class Student with the following details:

• name
• roll number
• marks in 3 subjects

👉 Perform the following:

1. Calculate total marks
2. Calculate average
3. Display result (Pass/Fail if average ≥ 40)
4. Display all details neatly

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💡 Concept

👉 Classes, objects, methods

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🔍 Hint

• Create methods: calculateTotal(), calculateAverage()
• Use conditional statements
• Create object in main

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🧪 Program 2: Employee Salary System (Constructor)

📌 Question

Create a class Employee with:

• name
• basic salary

👉 Perform:

1. Use constructor to initialize values
2. Calculate:
   • HRA = 20% of salary
   • DA = 10%
3. Calculate total salary
4. Display all details

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💡 Concept

👉 Constructor + calculations

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🔍 Hint

• Use this keyword
• Create method calculateSalary()

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🧪 Program 3: Calculator using Method Overloading

📌 Question

Create a class Calculator that can:

1. Add 2 integers
2. Add 3 integers
3. Add 2 double values
4. Multiply 2 numbers

👉 Display results for all cases

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💡 Concept

👉 Method Overloading

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🔍 Hint

• Same method name add()
• Different parameters
• Create separate multiply()

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🧪 Program 4: Animal Information System (Inheritance)

📌 Question

Create:

• Class Animal:
  • name
  • age
  • method displayInfo()
• Class Dog:
  • breed
  • method bark()

👉 Display complete dog information

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💡 Concept

👉 Inheritance

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🔍 Hint

• Use extends
• Call parent method

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🟡 MEDIUM LEVEL (Concept Building)

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🧪 Program 5: Vehicle System (Method Overriding)

📌 Question

Create:

• Class Vehicle:
  • method start()
  • method stop()
• Class Car overrides both methods
• Class Bike overrides both methods

👉 Display behavior of each vehicle

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💡 Concept

👉 Method Overriding

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🔍 Hint

• Use same method names
• Use @Override
• Create multiple objects

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🧪 Program 6: Employee Hierarchy System

📌 Question

Create:

• Class Person:
  • name, age
• Class Employee:
  • salary
• Class Manager:
  • department

👉 Display full details of manager

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💡 Concept

👉 Multilevel Inheritance

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🔍 Hint

• Chain inheritance
• Create display method in each class

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🧪 Program 7: Shape Area Calculator (Abstract Class)

📌 Question

Create abstract class Shape:

• abstract method area()

Create subclasses:

• Circle → calculate area
• Rectangle → calculate area

👉 Display area of both

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💡 Concept

👉 Abstraction

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🔍 Hint

• Use abstract keyword
• Override in subclasses
• Use constructor for dimensions

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🔴 HARD LEVEL (Advanced Programs)

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🧪 Program 8: Library Management System

📌 Question

Create a system with:

• Class Book:
  • book name
  • author
  • price
• Class Library:
  • method to display books
  • method to search book

👉 Perform:

• Add at least 3 books
• Display all books
• Search by name

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💡 Concept

👉 Objects + arrays + real-world design

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🔍 Hint

• Use array of objects
• Use loop for search

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🧪 Program 9: Dynamic Polymorphism (Shapes Drawing)

📌 Question

Create:

• Class Shape with method draw()
• Subclasses:
  • Circle
  • Rectangle
  • Triangle

👉 Use parent reference to call methods dynamically

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💡 Concept

👉 Runtime polymorphism

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🔍 Hint

Shape s;
s = new Circle();
s.draw();

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🧪 Program 10: Banking System (Real-World)

📌 Question

Create a banking system:

• Class Account:
  • account number
  • balance
  • methods:
    • deposit()
    • withdraw()
• Subclasses:
  • SavingsAccount (limit withdrawal)
  • CurrentAccount (no limit)

👉 Perform:

• Deposit money
• Withdraw money
• Display balance

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💡 Concept

👉 Inheritance + overriding + real-world logic

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🔍 Hint

• Use validation (no negative balance)
• Override withdraw method

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⚠️ Common Mistakes

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❌ Not dividing logic into methods

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❌ Writing everything in main()

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❌ Forgetting inheritance keywords

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❌ Confusing overloading & overriding

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🤯 Common Confusions

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🤔 Abstract class vs normal class

• Abstract → cannot create object
• Normal → can create

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🤔 Overloading vs Overriding

Overloading	Overriding
Compile-time	Runtime

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💼 Viva Questions

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❓ What is constructor?

👉 Initializes object

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❓ What is inheritance?

👉 Reusing parent class properties

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❓ What is polymorphism?

👉 Same method, different behavior

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❓ What is abstraction?

👉 Hiding implementation

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🎯 Final Advice

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✔️ Practice each program
✔️ Write full code
✔️ Understand logic
✔️ Be ready to explain in viva

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🏁 Conclusion

This practical file now contains meaningful and slightly real-world programs 🎯

👉 If you complete these:

• Your OOP concepts will be crystal clear 💪
• You’ll be ready for exams & interviews 🚀

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🔥 One-Line Summary

👉 “Practice detailed OOP problems to truly master Java.”

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💻 Happy Coding! 😄

Consistency + Practice = Success 🔥