Object Oriented Programming With Java (4341602) - Summer 2023 Solution

Question 1(a) [3 marks]

Differentiate between Procedure-Oriented Programming (POP) and Object-Oriented Programming (OOP).

Answer:

Table:

• POP: Program divided into functions, data flows between functions
• OOP: Program organized around objects that contain both data and methods

Mnemonic: "POP Functions, OOP Objects"

---

Question 1(b) [4 marks]

Explain Super keyword in inheritance with suitable example.

Answer:

Super keyword is used to access parent class members from child class.

Table: Super keyword uses

Code Block:

Java

Mnemonic: "Super calls Parent"

---

Question 1(c) [7 marks]

Define: Method Overriding. List out Rules for method overriding. Write a java program that implements method overriding.

Answer:

Method Overriding: Child class provides specific implementation of parent class method with same signature.

Table: Method Overriding Rules

Code Block:

Java

Mnemonic: "Override Same Signature"

---

Question 1(c OR) [7 marks]

Describe: Interface. Write a java program using interface to demonstrate multiple inheritance.

Answer:

Interface: Blueprint containing abstract methods and constants. Classes implement interfaces to achieve multiple inheritance.

Table: Interface Features

Code Block:

Java

Mnemonic: "Interface Multiple Implementation"

---

Question 2(a) [3 marks]

Explain the Java Program Structure with example.

Answer:

Java Program Structure consists of package, imports, class declaration, and main method.

Diagram:

goat

Code Block:

Java

Mnemonic: "Package Import Class Main"

---

Question 2(b) [4 marks]

Explain static keyword with suitable example.

Answer:

Static keyword belongs to class rather than instance. Memory allocated once.

Table: Static Uses

Code Block:

Java

Mnemonic: "Static Shared by Class"

---

Question 2(c) [7 marks]

Define: Constructor. List out types of it. Explain Parameterized and copy constructor with suitable example.

Answer:

Constructor: Special method to initialize objects, same name as class, no return type.

Table: Constructor Types

Code Block:

Java

Mnemonic: "Constructor Initializes Objects"

---

Question 2(a OR) [3 marks]

Explain the Primitive Data Types and User Defined Data Types in java.

Answer:

Primitive Data Types: Built-in types provided by Java language. User Defined Types: Custom types created by programmer using classes.

Table: Data Types

• Primitive: Stored in stack, faster access
• User Defined: Stored in heap, complex operations

Mnemonic: "Primitive Built-in, User Custom"

---

Question 2(b OR) [4 marks]

Explain this keyword with suitable example.

Answer:

This keyword refers to current object instance, used to distinguish between instance and local variables.

Table: This keyword uses

Code Block:

Java

Mnemonic: "This Current Object"

---

Question 2(c OR) [7 marks]

Define Inheritance. List out types of it. Explain multilevel and hierarchical inheritance with suitable example.

Answer:

Inheritance: Mechanism where child class acquires properties and methods of parent class.

Table: Inheritance Types

Diagram - Multilevel:

Code Block - Multilevel:

Java

Diagram - Hierarchical:

Code Block - Hierarchical:

Java

Mnemonic: "Inheritance Shares Properties"

---

Question 3(a) [3 marks]

Explain Type Conversion and Casting in java.

Answer:

Type Conversion: Converting one data type to another. Casting: Explicit type conversion by programmer.

Table: Type Conversion

Code Block:

Java

Mnemonic: "Implicit Auto, Explicit Manual"

---

Question 3(b) [4 marks]

Explain different visibility controls used in Java.

Answer:

Visibility Controls (Access Modifiers): Control access to classes, methods, and variables.

Table: Access Modifiers

Code Block:

Java

Mnemonic: "Private Package Protected Public"

---

Question 3(c) [7 marks]

Define: Thread. List different methods used to create Thread. Explain Thread life cycle in detail.

Answer:

Thread: Lightweight subprocess that allows concurrent execution of multiple parts of program.

Table: Thread Creation Methods

Diagram: Thread Life Cycle

Table: Thread States

Code Block:

Java

Mnemonic: "Thread Concurrent Execution"

---

Question 3(a OR) [3 marks]

Explain the purpose of JVM in java.

Answer:

JVM (Java Virtual Machine): Runtime environment that executes Java bytecode and provides platform independence.

Table: JVM Components

Diagram:

goat

• Platform Independence: "Write Once, Run Anywhere"
• Memory Management: Automatic garbage collection
• Security: Bytecode verification

Mnemonic: "JVM Java Virtual Machine"

---

Question 3(b OR) [4 marks]

Define: Package. Write the steps to create a Package with suitable example.

Answer:

Package: Collection of related classes and interfaces grouped together, providing namespace and access control.

Table: Package Benefits

Steps to create Package:

1. Declare package at top of file
2. Create directory structure matching package name
3. Compile with package structure
4. Import in other classes

Code Block:

Java

Directory Structure:

com/
  company/
    utilities/
      Calculator.class
Main.class

Mnemonic: "Package Groups Classes"

---

Question 3(c OR) [7 marks]

Explain Synchronization in Thread with suitable example.

Answer:

Synchronization: Mechanism to control access to shared resources by multiple threads to avoid data inconsistency.

Table: Synchronization Types

Diagram: Without vs With Synchronization

Code Block:

Java

Mnemonic: "Synchronization Prevents Race Conditions"

---

Question 4(a) [3 marks]

Differentiate between String class and StringBuffer class.

Answer:

Table: String vs StringBuffer

Code Block:

Java

• String: Use when content doesn't change frequently
• StringBuffer: Use when frequent modifications needed

Mnemonic: "String Immutable, StringBuffer Mutable"

---

Question 4(b) [4 marks]

Write a Java Program to find sum and average of 10 numbers of an array.

Answer:

Code Block:

Java

Output:

Array elements: 10 20 30 40 50 60 70 80 90 100
Sum: 550
Average: 55.0

Logic Steps:

1. Initialize array with 10 numbers
2. Loop through array to calculate sum
3. Calculate average = sum / length
4. Display results

Mnemonic: "Loop Sum Divide Average"

---

Question 4(c) [7 marks]

I) Explain abstract class with suitable example. II) Explain final class with suitable example.

Answer:

I) Abstract Class: Class that cannot be instantiated, contains abstract methods that must be implemented by subclasses.

Table: Abstract Class Features

Code Block - Abstract Class:

Java

II) Final Class: Class that cannot be extended (no inheritance allowed).

Table: Final Class Features

Code Block - Final Class:

Java

Mnemonic: "Abstract Incomplete, Final Complete"

---

Question 4(a OR) [3 marks]

Explain Garbage Collection in Java.

Answer:

Garbage Collection: Automatic memory management process that removes unused objects from heap memory.

Table: GC Benefits

Diagram:

goat

• When occurs: When heap memory is low or System.gc() called
• Process: Mark and Sweep algorithm
• Cannot guarantee: Exact timing of garbage collection

Mnemonic: "GC Automatic Memory Cleanup"

---

Question 4(b OR) [4 marks]

Write a Java program to handle user defined exception for 'Divide by Zero' error.

Answer:

Code Block:

Java

Output:

Error: Cannot divide by zero!

Steps:

1. Create custom exception class extending Exception
2. Throw exception when condition occurs
3. Handle exception with try-catch block

Mnemonic: "Custom Exception Handle Error"

---

Question 4(c OR) [7 marks]

Write a java program to demonstrate multiple try block and multiple catch block exception.

Answer:

Code Block:

Java

Output:

Array index error: Index 5 out of bounds for length 3
Null pointer error: null
Arithmetic error: / by zero
Program completed

Features demonstrated:

• Multiple try blocks: Each handles different operations
• Multiple catch blocks: Each handles specific exception type
• Exception hierarchy: General Exception catches all
• Finally block: Always executes

Mnemonic: "Multiple Try Multiple Catch"

---

Question 5(a) [3 marks]

Write a program in Java to create a file and perform write operation on this file.

Answer:

Code Block:

Java

Steps:

1. Import java.io package
2. Create File object with filename
3. Create FileWriter object
4. Write data using write() method
5. Close writer to save changes

Mnemonic: "File Writer Write Close"

---

Question 5(b) [4 marks]

Explain throw and finally in Exception Handling with example.

Answer:

Throw: Keyword used to explicitly throw an exception. Finally: Block that always executes regardless of exception occurrence.

Table: Throw vs Finally

Code Block:

Java

Output:

Error: Age must be 18 or above
Finally block always executes

• Throw: Forces exception to occur
• Finally: Cleanup code, closes resources

Mnemonic: "Throw Exception, Finally Always"

---

Question 5(c) [7 marks]

Describe: Polymorphism. Explain run time polymorphism with suitable example in java.

Answer:

Polymorphism: One interface, multiple implementations. Object behaves differently based on its actual type.

Table: Polymorphism Types

Run-time Polymorphism: Method call resolved at runtime based on actual object type.

Diagram:

Code Block:

Java

Output:

Dog barks
Cat meows
Dog barks
Cat meows
Dog barks

Features:

• Dynamic Method Dispatch: JVM decides which method to call at runtime
• Upcasting: Child object referenced by parent reference
• Flexibility: Same code works with different object types

Mnemonic: "Polymorphism Many Forms Runtime"

---

Question 5(a OR) [3 marks]

Write a program in Java that read the content of a file byte by byte and copy it into another file.

Answer:

Code Block:

Java

Steps:

1. Create FileInputStream for reading
2. Create FileOutputStream for writing
3. Read byte by byte using read()
4. Write each byte using write()
5. Close both streams

Mnemonic: "Read Byte Write Byte"

---

Question 5(b OR) [4 marks]

Explain the different I/O Classes available with Java.

Answer:

Table: Java I/O Classes

Diagram: I/O Class Hierarchy

goat

Code Example:

Java

Mnemonic: "Byte Character Buffered Streams"

---

Question 5(c OR) [7 marks]

Write a java program that executes two threads. One thread displays "Java Programming" every 3 seconds, and the other displays "Semester - 4th IT" every 6 seconds.(Create the threads by extending the Thread class)

Answer:

Code Block:

Java

Sample Output:

Java Programming
Semester - 4th IT
Java Programming
Java Programming
Semester - 4th IT
Java Programming
Java Programming
Semester - 4th IT
...

Features:

• Two separate threads: Each with different timing
• Thread.sleep(): Pauses execution for specified milliseconds
• Concurrent execution: Both threads run simultaneously
• Extending Thread class: Override run() method

Execution Pattern:

• JavaThread: Displays every 3 seconds
• SemesterThread: Displays every 6 seconds
• Both run concurrently showing different timing

Mnemonic: "Two Threads Different Timing"