Java Programming (4343203) - Summer 2024 Solution

Question 1(a) [3 marks]

Explain Garbage collection in java.

Answer: Garbage collection in Java automatically reclaims memory by removing unused objects.

Table: Garbage Collection Process

• Automatic: No manual memory management required
• Background: Runs in separate low-priority thread

Mnemonic: "MSC: Mark-Sweep-Compact frees memory automatically"

Question 1(b) [4 marks]

Explain JVM in detail.

Answer: JVM (Java Virtual Machine) is a virtual machine that enables Java's platform independence by converting bytecode to machine code.

Diagram: JVM Architecture

• Platform Independence: Write once, run anywhere
• Security: Bytecode verification prevents dangerous operations
• Optimization: Just-in-time compilation improves performance

Mnemonic: "CLASS: Class Loader Leads All System Security"

Question 1(c) [7 marks]

Write a program in java to print Fibonacci series for N terms.

Answer: Fibonacci series generates numbers where each is the sum of the two preceding ones.

Code Block:

Java

• Initialize: Start with 0 and 1
• Loop: Iterate N times to generate sequence
• Calculation: Each number is sum of previous two

Mnemonic: "FSN: First + Second = Next number in sequence"

Question 1(c OR) [7 marks]

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

Answer: Command line arguments allow passing input values directly when executing a Java program.

Code Block:

Java

• Parse Arguments: Convert string arguments to integers
• Initialize: Set first number as minimum
• Compare: Check each number against current minimum

Mnemonic: "ICU: Initialize, Compare, Update the minimum"

Question 2(a) [3 marks]

List out basic concepts of Java OOP. Explain any one in details.

Answer: Java Object-Oriented Programming is built on fundamental concepts for modeling real-world entities.

Table: OOP Concepts in Java

• Encapsulation: Protects data through access control
• Data Hiding: Private variables accessible through methods

Mnemonic: "PEAI: Programming Encapsulates Abstracts Inherits"

Question 2(b) [4 marks]

Explain final keyword with example.

Answer: The final keyword in Java restricts modification and creates constants, unchangeable methods, and non-inheritable classes.

Table: Uses of final Keyword

Code Block:

Java

Mnemonic: "VCM: Variables Constants Methods can't change"

Question 2(c) [7 marks]

What is constructor? Explain parameterized constructor with example.

Answer: A constructor initializes objects when created, with the same name as its class and no return type.

Diagram: Constructor Types

Code Block:

Java

• Parameters: Accept values during object creation
• Initialization: Set object properties with passed values
• Overloading: Multiple constructors with different parameters

Mnemonic: "SPO: Student Parameters Object initializes properties"

Question 2(a OR) [3 marks]

Explain the Java Program Structure with example.

Answer: Java program structure follows a specific hierarchy of elements organized logically.

Diagram: Java Program Structure

• Package: Groups related classes
• Import: Includes external classes
• Class: Contains variables and methods

Mnemonic: "PIC: Package Imports Class in every program"

Question 2(b OR) [4 marks]

Explain static keyword with suitable example.

Answer: Static keyword creates class-level variables and methods shared by all objects, accessible without creating instances.

Table: Static vs Non-Static

Code Block:

Java

Mnemonic: "SCM: Static Creates Memory once for all objects"

Question 2(c OR) [7 marks]

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

Answer: Inheritance is an OOP principle where a new class acquires properties and behaviors from an existing class.

Table: Types of Inheritance in Java

Diagram: Multilevel vs Hierarchical Inheritance

Code Block:

Java

Mnemonic: "SMHM: Single Multilevel Hierarchical Makes inheritance types"

Question 3(a) [3 marks]

Explain this keyword with suitable example.

Answer: The 'this' keyword in Java refers to the current object, used to differentiate between instance variables and parameters.

Table: Uses of 'this' Keyword

Code Block:

Java

Mnemonic: "VAR: Variables Access Resolution using this"

Question 3(b) [4 marks]

Explain different access controls in Java.

Answer: Access controls in Java regulate visibility and accessibility of classes, methods, and variables.

Table: Java Access Modifiers

• Private: Only within the same class
• Default: Within the same package
• Protected: Within package and subclasses
• Public: Accessible everywhere

Mnemonic: "PDPP: Private Default Protected Public from narrow to wide"

Question 3(c) [7 marks]

What is interface? Explain multiple inheritance using interface with example.

Answer: An interface is a contract that specifies what a class must do, containing abstract methods, constants, and (since Java 8) default methods.

Diagram: Multiple Inheritance with Interfaces

Code Block:

Java

• Contract: Defines behavior without implementation
• Implements: Classes fulfill the contract
• Multiple: Can implement many interfaces

Mnemonic: "CIM: Contract Implements Multiple interfaces"

Question 3(a OR) [3 marks]

Explain super keyword with example.

Answer: The super keyword refers to the parent class, used to access parent methods, constructors, and variables.

Table: Uses of super Keyword

Code Block:

Java

Mnemonic: "VMC: Variables Methods Constructors accessed by super"

Question 3(b OR) [4 marks]

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

Answer: A package in Java is a namespace that organizes related classes and interfaces, preventing naming conflicts.

Table: Steps to Create a Package

Code Block:

Java

Mnemonic: "DISCO: Declare Import Save Compile Organize"

Question 3(c OR) [7 marks]

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

Answer: Method overriding occurs when a subclass provides a specific implementation for a method already defined in its parent class.

Table: Rules for Method Overriding

Code Block:

Java

• Runtime Polymorphism: Method resolution at runtime
• @Override: Annotation ensures method is overriding
• Inheritance: Requires IS-A relationship

Mnemonic: "SPARE: Same Parameters Access Return Exceptions"

Question 4(a) [3 marks]

Explain abstract class with suitable example.

Answer: An abstract class cannot be instantiated and may contain abstract methods that must be implemented by subclasses.

Table: Abstract Class vs Interface

Code Block:

Java

Mnemonic: "PAI: Partial Abstract Implementation is key"

Question 4(b) [4 marks]

What is Thread? Explain Thread life cycle.

Answer: A thread is a lightweight subprocess, the smallest unit of processing that allows concurrent execution.

Diagram: Thread Life Cycle

• New: Thread created but not started
• Runnable: Ready to run when CPU time is given
• Running: Currently executing
• Blocked/Waiting: Temporarily inactive
• Terminated: Completed execution

Mnemonic: "NRRBT: New Runnable Running Blocked Terminated"

Question 4(c) [7 marks]

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

Answer: Creating threads by implementing Thread class allows multiple tasks to execute concurrently.

Code Block:

Java

• Extend Thread: Create thread by extending Thread class
• Override run(): Define task in run method
• start(): Begin thread execution

Mnemonic: "ERS: Extend Run Start to create threads"

Question 4(a OR) [3 marks]

Explain final class with suitable example.

Answer: A final class cannot be extended, preventing inheritance and modification of its design.

Table: Final Class Characteristics

Code Block:

Java

• Security: Protects sensitive implementations
• Immutability: Helps create immutable classes
• Optimization: JVM can optimize final classes

Mnemonic: "SIO: Security Immutability Optimization"

Question 4(b OR) [4 marks]

Explain thread priorities with suitable example.

Answer: Thread priorities determine the order in which threads are scheduled for execution, from 1 (lowest) to 10 (highest).

Table: Thread Priority Constants

Code Block:

Java

Mnemonic: "HNL: High Normal Low priorities in threads"

Question 4(c OR) [7 marks]

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

Answer: An exception is an abnormal condition that disrupts the normal flow of program execution.

Diagram: Exception Hierarchy

Code Block:

Java

• Try Block: Contains code that might throw exceptions
• Catch Block: Handles the specific exception
• Finally Block: Always executes regardless of exception

Mnemonic: "TCF: Try Catch Finally handles exceptions"

Question 5(a) [3 marks]

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

Answer: Arrays store multiple values of the same type, enabling sequential processing of elements.

Code Block:

Java

• Declaration: Creates fixed-size collection
• Iteration: Sequential access to elements
• Calculation: Process values for results

Mnemonic: "DIC: Declare Iterate Calculate for array processing"

Question 5(b) [4 marks]

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

Answer: User-defined exceptions allow creating custom exception types for specific application requirements.

Code Block:

Java

• Custom Class: Extends Exception class
• Throwing: Use throw keyword with new instance
• Handling: Catch specific exception type

Mnemonic: "CTE: Create Throw Exception when needed"

Question 5(c) [7 marks]

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

Answer: Java provides I/O classes to work with files, allowing creation, writing, and reading operations.

Code Block:

Java

• FileWriter: Creates and writes to files
• FileReader: Reads character data from files
• BufferedReader: Efficiently reads text by lines

Mnemonic: "WRC: Write Read Close for file operations"

Question 5(a OR) [3 marks]

Explain java I/O process.

Answer: Java I/O process involves transferring data to and from various sources using streams.

Table: Java I/O Stream Types

Diagram: Java I/O Hierarchy

• Stream: Sequence of data flowing between source and destination
• Buffering: Improves performance by reducing disk access

Mnemonic: "SBI: Stream Buffered Input/Output"

Question 5(b OR) [4 marks]

Explain throw and finally in Exception Handling with example.

Answer: Exception handling mechanisms control program flow during errors, ensuring graceful execution.

Table: throw vs finally

Code Block:

Java

Mnemonic: "TERA: Throw Exception Regardless Always finally executes"

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.

Code Block:

Java

• FileWriter(file, true): Second parameter enables append mode
• BufferedReader: Efficiently reads text by lines
• Reusable Method: Encapsulates reading functionality

Mnemonic: "CAD: Create Append Display file operations"