Object Oriented Programming with Java (4341602) - Summer 2024 Solution

Question 1(a) [3 marks]

Explain the basic structure of Java program.

Answer:

Basic Structure Table:

Diagram:

goat

• Package: Groups related classes
• Import: Access external classes
• Class: Blueprint for objects
• Main method: Program execution starts here

Mnemonic: "PICM - Package, Import, Class, Main"

Question 1(b) [4 marks]

List out different features of java. Explain any two.

Answer:

Java Features Table:

Detailed Explanation:

Platform Independence:

• Java code compiles to bytecode
• JVM interprets bytecode on any platform
• Same program runs on Windows, Linux, Mac

Object Oriented:

• Encapsulation: Data hiding in classes
• Inheritance: Code reuse through extends
• Polymorphism: Same method, different behavior

Mnemonic: "POSRMM - Platform, Object, Simple, Robust, Multithreaded, Memory"

Question 1(c) [7 marks]

Write a program in java to find out sum of the digits of entered number. (Ex. Number is 123 output is 6).

Answer:

Java

Algorithm Table:

• Input: Command line argument
• Process: Extract digits using modulo
• Output: Sum of all digits

Mnemonic: "EARD - Extract, Add, Remove, Done"

Question 1(c OR) [7 marks]

Write a program in java to find out maximum from any ten numbers using command line argument.

Answer:

Java

Process Table:

• Validation: Check argument count
• Comparison: Standard maximum finding
• Output: Display the largest number

Mnemonic: "VCIU - Validate, Compare, Initialize, Update"

Question 2(a) [3 marks]

List out different concept of oop. Explain anyone in detail.

Answer:

OOP Concepts Table:

Encapsulation Details:

• Combines data and methods in single unit
• Uses private access modifiers for data
• Provides public getter/setter methods
• Protects data from unauthorized access

Benefits:

• Security: Data protection
• Maintenance: Easy code updates
• Flexibility: Change implementation easily

Mnemonic: "EIPA - Encapsulation, Inheritance, Polymorphism, Abstraction"

Question 2(b) [4 marks]

Explain JVM in detail.

Answer:

JVM Architecture Diagram:

JVM Components Table:

• Platform Independence: Same bytecode runs everywhere
• Memory Management: Automatic garbage collection
• Security: Bytecode verification before execution

Mnemonic: "CEMJ - Class loader, Execution, Memory, JIT"

Question 2(c) [7 marks]

Explain constructor overloading with example.

Answer:

Java

Constructor Types Table:

• Same name: All constructors have class name
• Different parameters: Number or type varies
• Compile-time: Decision made during compilation

Mnemonic: "SNDF - Same Name, Different Parameters, Flexible"

Question 2(a OR) [3 marks]

What is wrapper class? Explain with example.

Answer:

Wrapper Classes Table:

Example:

Java

• Boxing: Convert primitive to wrapper object
• Unboxing: Extract primitive from wrapper
• Collections: Only objects allowed in collections

Mnemonic: "BUC - Boxing, Unboxing, Collections"

Question 2(b OR) [4 marks]

Explain static keyword with example.

Answer:

Java

Static Features Table:

• Class level: Belongs to class, not instance
• Memory efficiency: Single copy for all objects
• Access: Use class name to access

Mnemonic: "SCMA - Shared, Class-level, Memory, Access"

Question 2(c OR) [7 marks]

What is constructor? Explain copy constructor with example.

Answer:

Constructor Definition: Constructor is a special method that initializes objects when they are created.

Java

Constructor Types Table:

• Same name: Constructor name = class name
• No return type: Not even void
• Automatic call: Called when object created

Mnemonic: "SNAC - Same Name, Automatic Call"

Question 3(a) [3 marks]

Explain any four-string function in java with example.

Answer:

String Functions Table:

Code Example:

Java

• Immutable: String objects cannot be changed
• Return new: Methods return new string objects
• Zero-indexed: Position counting starts from 0

Mnemonic: "LCST - Length, Character, Substring, Transform"

Question 3(b) [4 marks]

List out different types of inheritance. Explain multilevel inheritance.

Answer:

Inheritance Types Table:

Multilevel Inheritance Diagram:

Example:

Java

• Chain inheritance: Grandparent → Parent → Child
• Feature accumulation: Child gets all ancestor features
• Method access: Can call methods from all levels

Mnemonic: "SMHM - Single, Multilevel, Hierarchical, Multiple"

Question 3(c) [7 marks]

What is interface? Explain multiple inheritance with example.

Answer:

Interface Definition: Interface is a contract that defines what methods a class must implement, without providing implementation.

Java

Interface vs Class Table:

Multiple Inheritance Diagram:

• Contract: Defines what, not how
• Multiple implementation: One class, many interfaces
• Diamond problem solution: Interfaces solve multiple inheritance issues

Mnemonic: "CMDS - Contract, Multiple, Diamond-solution"

Question 3(a OR) [3 marks]

Explain this keyword with example.

Answer:

'this' Keyword Uses Table:

Example:

Java

• Current object: Refers to current instance
• Parameter conflict: Resolve naming conflicts
• Method chaining: Enable fluent interface

Mnemonic: "CRPM - Current, Resolve, Parameter, Method"

Question 3(b OR) [4 marks]

Explain method overriding with example.

Answer:

Java

Overriding Rules Table:

Usage:

Java

• Runtime polymorphism: Decision made during execution
• Same interface: Different behavior for different classes
• Dynamic binding: Method resolution at runtime

Mnemonic: "SSRD - Same Signature, Runtime Decision"

Question 3(c OR) [7 marks]

What is package? Write steps to create a package and give example of it.

Answer:

Package Definition: Package is a namespace that organizes related classes and interfaces, providing access control and avoiding naming conflicts.

Steps to Create Package:

Example Package Structure:

src/
  com/
    company/
      utils/
        MathUtils.java
        StringUtils.java
      models/
        Student.java

MathUtils.java:

Java

Using Package:

Java

Package Benefits Table:

Mnemonic: "ONAM - Organization, Namespace, Access, Maintenance"

Question 4(a) [3 marks]

Explain thread priorities with suitable example.

Answer:

Thread Priority Table:

Example:

Java

• Higher priority: More likely to get CPU time
• Not guaranteed: JVM decides actual scheduling
• Default priority: Every thread starts with NORM_PRIORITY

Mnemonic: "HNG - Higher priority, Not Guaranteed"

Question 4(b) [4 marks]

What is Thread? Explain Thread life cycle.

Answer:

Thread Definition: Thread is a lightweight sub-process that allows concurrent execution of multiple tasks within a program.

Thread Life Cycle Diagram:

Thread States Table:

State Transitions:

• NEW → RUNNABLE: start() method called

• RUNNABLE → RUNNING: Thread scheduler assigns CPU

• RUNNING → BLOCKED: Waiting for I/O or lock

• RUNNING → TERMINATED: run() method completes

• Concurrent execution: Multiple threads run simultaneously

• JVM managed: Thread scheduler controls execution

• Resource sharing: Threads share memory space

Mnemonic: "NRBT - New, Runnable, Blocked, Terminated"

Question 4(c) [7 marks]

Write a program in java that create the multiple threads by implementing the Thread class.

Answer:

Java

Implementation Steps Table:

• Extends Thread: Inherit threading capabilities
• Override run(): Define thread's execution logic
• start() method: Begin thread execution
• Concurrent execution: All threads run simultaneously

Mnemonic: "EOCS - Extend, Override, Create, Start"

Question 4(a OR) [3 marks]

Explain basic concept of Exception Handling.

Answer:

Exception Handling Concepts Table:

Exception Hierarchy:

Basic Syntax:

Java

• Graceful handling: Program continues after exception
• Error prevention: Avoid program crash
• Resource cleanup: finally block ensures cleanup

Mnemonic: "TRCF - Try, Runtime error, Catch, Finally"

Question 4(b OR) [4 marks]

Explain multiple catch with suitable example.

Answer:

Java

Multiple Catch Rules Table:

Exception Flow:

• ArrayIndexOutOfBoundsException: Invalid array access
• ArithmeticException: Division by zero
• NumberFormatException: Invalid number conversion
• Exception: Catches any remaining exceptions

Mnemonic: "SOOF - Specific first, One executes, Order matters, Finally"

Question 4(c OR) [7 marks]

What is Exception? Write a program that show the use of Arithmetic Exception.

Answer:

Exception Definition: Exception is an event that occurs during program execution and disrupts the normal flow of instructions.

Java

Exception Types Table:

ArithmeticException Causes:

• Division by zero: Most common cause
• Modulo by zero: Remainder operation with zero
• Invalid operations: Mathematical impossibilities

Program Flow:

1. Normal execution: Try block runs
2. Exception occurs: ArithmeticException thrown
3. Exception caught: Catch block handles it
4. Cleanup: Finally block executes
5. Continue: Program continues after handling

Mnemonic: "DZMI - Division by Zero, Mathematical Invalid"

Question 5(a) [3 marks]

Explain ArrayIndexOutOfBound Exception in Java with example.

Answer:

ArrayIndexOutOfBound Exception Table:

Example:

Java

• Runtime exception: Occurs during program execution
• Index validation: Always check array bounds
• Prevention: Use array.length for bounds checking

Mnemonic: "NIE - Negative, Index-exceed, Empty"

Question 5(b) [4 marks]

Explain basics of stream classes.

Answer:

Stream Classes Hierarchy:

Stream Types Table:

Basic Operations:

• Input: Read data from source
• Output: Write data to destination
• Buffering: Store data temporarily for efficiency
• Closing: Release system resources

Stream Benefits:

• Abstraction: Uniform interface for I/O
• Efficiency: Buffered operations
• Flexibility: Various data sources/destinations

Mnemonic: "BCIF - Byte, Character, Input/Output, File"

Question 5(c) [7 marks]

Write a java program to create a text file and perform write operation on the text file.

Answer:

Java

File Write Methods Table:

Write Operation Steps:

1. Create writer object: FileWriter or BufferedWriter
2. Write data: Use write() method
3. Close stream: Release resources
4. Handle exceptions: IOException management

File Operations:

• Create: New file if doesn't exist
• Overwrite: Replaces existing content
• Append: Add to existing content (use append mode)

Mnemonic: "CWCH - Create, Write, Close, Handle"

Question 5(a OR) [3 marks]

Explain Divide by Zero Exception in Java with example.

Answer:

Divide by Zero Exception Table:

Example:

Java

• Integer arithmetic: Throws ArithmeticException
• Floating point: Returns Infinity (IEEE 754 standard)
• Prevention: Check denominator before division

Mnemonic: "IFM - Integer exception, Float infinity, Modulo error"

Question 5(b OR) [4 marks]

Explain try and catch block with example.

Answer:

Try-Catch Structure:

Java

Example:

Java

Try-Catch Flow Table:

• Exception matching: First matching catch block executes
• Control flow: Program continues after catch block
• Multiple catches: Handle different exception types

Mnemonic: "TCF - Try risky, Catch exception, Finally cleanup"

Question 5(c OR) [7 marks]

Write a java program to display the content of a text file and perform append operation on the text file.

Answer:

Java

File Operations Table:

File Operations Flow:

1. Create initial file: Write initial content
2. Display content: Read and show current content
3. Append data: Add new information
4. Display updated: Show modified content
5. Statistics: Count lines and characters

Append vs Write:

• Write mode: Overwrites existing content
• Append mode: Adds to end of existing content
• Constructor parameter: Second parameter true enables append

Resource Management:

• Try-with-resources: Automatic close()
• Exception handling: FileNotFoundException, IOException
• Buffered operations: Better performance for large files

Mnemonic: "CDADS - Create, Display, Append, Display, Statistics"