IGNOU BCA Object-Oriented Technologies and Java Programming Previous Year Solved Papers MCS 024

Preface

Over the past decade, academic progress and technological innovations have significantly reshaped the educational landscape, with Java programming emerging as a cornerstone in computer science and software development. As programming continues to play a vital role in shaping modern technologies, mastering Java has become essential for students aiming to excel in the IT industry.

In this transformative journey, the Indira Gandhi National Open University (IGNOU) has consistently empowered learners by offering accessible and high-quality education. In response to the growing demand for reliable academic support, we are pleased to present IGNOU BCA Object-Oriented Technologies and Java Programming Previous Year Solved Papers MCS 024 — a carefully curated compilation designed to support students in strengthening their understanding of Java and object-oriented programming concepts.

This book brings together solved question papers from the past ten years, offering readers not only a window into real exam patterns and expectations but also the opportunity to enhance their problem-solving techniques and application-based understanding. Developed through the collaborative efforts of experienced educators and industry professionals, the solutions reflect a balance of theoretical knowledge and practical insight.

Whether used for exam preparation, self-assessment, or concept revision, this volume aims to be a dependable academic companion. We believe that by working through these solved papers, learners will gain the confidence and clarity needed to approach Java programming with competence and enthusiasm.

We extend our sincere thanks to the educators, students, and reviewers who contributed to the making of this book. May it serve as a valuable guide for all those embarking on their journey through the world of object-oriented technologies and Java programming.

Table of Contents

Preface

Chapter 1: Term-End Examination, June- 2010

Chapter 2: Term-End Examination, December- 2010

Chapter 3: Term-End Examination, June- 2011

Chapter 4: Term-End Examination, June- 2012

Chapter 5: Term-End Examination, December- 2012

Chapter 6: Term-End Examination, June- 2013

Chapter 7: Term-End Examination, December- 2013

Chapter 8: Term-End Examination, June-2014

Chapter 9: Term-End Examination, December-2014

Chapter 10: Term-End Examination, June- 2015

Chapter 11: Term-End Examination, December- 2015

Chapter 12: Term-End Examination, June- 2016

Chapter 13: Term-End Examination, December- 2016

Chapter 14: Term-End Examination, June- 2017

Chapter 15: Term-End Examination, December- 2017

Chapter 16: Term-End Examination, June- 2018

Chapter 17: Term-End Examination, December- 2018

Chapter 18: Term-End Examination, June- 2019

Chapter 19: Term-End Examination, December- 2020

Chapter 20: Term-End Examination, June-2021

Chapter 21: Term-End Examination, December- 2021

Chapter 22: Term-End Examination, JUNE- 2022

Chapter 23: Term-End Examination, December- 2022

Chapter 24: Term-End Examination, June- 2023

MCA(Revised)/BCA(Revised)

Chapter 1: Term-End Examination, June- 2010

MCS-024: OBJECT-ORIENTED TECHNOLOGIES AND JAVA PROGRAMMING

1. (a) Consider a class that stores a Bank account 6 holder's account number, ATM card number, account balance and ATM PIN. Write a program to store the data onto a disk file, except for the account balance and ATM PIN. Use serialization and transient variables.

Ans - In Java, you can use the Serializable interface to serialize objects and save them to a disk file. To exclude certain fields from serialization, you can use the transient keyword. Here's a sample program that demonstrates how to do this for a class representing a bank account:

Example-

import java.io.*;

class BankAccount implements Serializable {

private int accountNumber;

private transient int atmCardNumber; // Mark as transient to exclude from serialization

private double accountBalance;

private transient int atmPin; // Mark as transient to exclude from serialization

public BankAccount(int accountNumber, int atmCardNumber, double accountBalance, int atmPin) {

this.accountNumber = accountNumber;

this.atmCardNumber = atmCardNumber;

this.accountBalance = accountBalance;

this.atmPin = atmPin;

}

// Other methods and getters/setters here

@Override

public String toString() {

return Account Number: + accountNumber + , Account Balance: + accountBalance;

}

}

public class BankAccountSerialization {

public static void main(String[] args) {

// Create a BankAccount object

BankAccount account = new BankAccount(123456, 7890, 1000.0, 1234);

// Serialize the object to a file

try (FileOutputStream fileOut = new FileOutputStream(bankaccount.ser);

ObjectOutputStream out = new ObjectOutputStream(fileOut)) {

out.writeObject(account);

System.out.println(BankAccount object has been serialized and saved to 'bankaccount.ser');

} catch (IOException e) {

e.printStackTrace();

}

// Deserialize the object (if needed)

try (FileInputStream fileIn = new FileInputStream(bankaccount.ser);

ObjectInputStream in = new ObjectInputStream(fileIn)) {

BankAccount deserializedAccount = (BankAccount) in.readObject();

System.out.println(Deserialized BankAccount: + deserializedAccount);

} catch (IOException | ClassNotFoundException e) {

e.printStackTrace();

}

}

}

In this example, the atm Card Number and atm Pin fields are marked as transient, so they won't be serialized when you save the Bank Account object to a file. This ensures sensitive information like the ATM card number and PIN are not stored in the serialized file.

Make sure to handle exceptions and file I/O properly in a real application, and consider encrypting the sensitive data for additional security.

(b) What makes compiled JAVA programs platform independent? Explain.

Ans- Compiled Java programs are platform-independent primarily due to the use of the Java Virtual Machine (JVM) and the Write Once, Run Anywhere philosophy.

Here's an explanation in Java:

Java Virtual Machine (JVM): Java programs are compiled into an intermediate form called Bytecode. Bytecode is a low-level representation of the program that is not specific to any particular hardware or operating system. The JVM is responsible for executing this bytecode. Each platform (Windows, macOS, Linux, etc.) has its own implementation of the JVM, which is responsible for translating the bytecode into machine code that is understood by the specific platform. This means that the same bytecode can run on any platform with the appropriate JVM.

Platform-Independent Bytecode: When you compile a Java program, it's transformed into bytecode, which is a set of instructions for the JVM. This bytecode is platform-independent, and it can run on any platform that has a compatible JVM.

No Native Code: Java doesn't rely on platform-specific native code. In contrast, languages like C or C++ compile directly to machine code, which is specific to the platform. This is why Java programs are more portable.

Standard Libraries: Java provides a standard library (the Java Standard Library) that is consistent across all platforms. This means that you can use Java's built-in classes and methods to perform various tasks without worrying about platform-specific differences.

Just-In-Time Compilation (JIT): JVMs often use Just-In-Time Compilation to further optimize the execution of Java programs. JIT compilers translate bytecode into native machine code at runtime, which can improve performance. This machine code is specific to the platform, but is generated on the fly by the JVM, allowing the same Java bytecode to run efficiently on different platforms.

Class Loading: Java classes are loaded by the JVM dynamically as they are needed. This allows Java applications to adapt to the specifics of the host platform at runtime, ensuring that the right classes are loaded and executed correctly on any platform.

Strict Language Specification: Java enforces a strict and standardized language specification. This minimizes variations in behaviour between different platforms and JVM implementations.

(c) Explain the significance of PATH and CLASS PATH.

Ans- PATH and CLASSPATH are environment variables used in Java (and other programming languages) to specify the locations of executable files and Java classes, respectively. They are essential for the proper functioning of Java applications and tools.

PATH:

Significance: The PATH environment variable is used by the operating system to locate executable files or scripts. When you run a command in the command prompt or terminal, the operating system searches for the executable in the directories listed in the PATH. If the executable is found in one of these directories, the command can be executed without specifying the full path to the executable.

In the Context of Java: For Java developers and users, the PATH is significant because it includes the directory where the Java runtime (e.g., java.exe on Windows or java on Unix-based systems) is located. This allows you to run Java applications and tools like the Java Compiler (javac) from any directory without specifying the full path.

Example: If your java.exe is located in C:\Program Files\Java\jdk-16\bin, and C:\Program Files\Java\jdk-16\bin is in your PATH, you can run Java applications from any directory without needing to specify the full path to java.exe.

CLASSPATH:

Significance: The CLASSPATH environment variable is used by the Java Virtual Machine (JVM) to locate Java classes or libraries required by a Java application. It specifies directories or JAR (Java Archive) files where Java classes can be found.

In the Context of Java: CLASSPATH is essential for Java applications that require external classes or libraries. When you compile or run a Java program that uses external classes or libraries, the JVM looks in the directories specified in CLASSPATH to find those classes.

Example: If you have a Java library in a JAR file named mylibrary.jar located in C:\lib, you can set the CLASSPATH to include this location. When you run your Java program, the JVM will look in C:\lib\mylibrary.jar for the required classes.

Note: In recent versions of Java, the use of CLASSPATH for finding classes has been largely supplanted by the use of the -cp or -classpath command-line option when compiling or running Java programs. This allows for a more flexible and isolated way of specifying class locations, without needing to set a global CLASSPATH environment variable.

(d) Is this a complete and legal comment? / * // */ Justify.

Ans- No, the given comment is not a complete and legal comment in Java. Java comments can be written in several ways, but they must follow the rules defined by the Java language. In this case, the provided comment is not following the correct syntax for Java comments.

Here's the correct way to write comments in Java:

Single-line comments: You can use // to create a single-line comment. Anything after // on the same line is considered a comment and is ignored by the Java compiler.

Example:

// This is a valid single-line comment

int x = 10; // This is also a valid comment

Multi-line comments: You can use /* to start a multi-line comment and */ to end it. Everything between /* and */ is treated as a comment.

Example:

/*

This is a valid multi-line comment.

It can span multiple lines.

*/

int y = 20; /* This is also a valid multi-line comment */

In the given code, 2 /* // */ is not a valid comment because it's a mix of different comment styles and doesn't follow the rules for single-line or multi-line comments. This code may lead to a compilation error in Java.

(e)Are inner class secure and useful?

Ans- Inner classes in Java are not necessarily more or less secure than regular classes; their security largely depends on how they are used and the design of your application. Inner classes can be secure and useful, but their appropriateness depends on the context and the specific problem you're trying to solve.

Here are some considerations regarding the security and usefulness of inner classes:

1. Security:

Access Control: Inner Classes can access private members of the outer class, which can be both an advantage and a potential security concern. It allows you to encapsulate data effectively, but it also means that you need to be cautious about granting access to inner classes and who can instantiate them.

Access Outside the Outer Class: Inner Classes are visible only within the outer class. This can be a security advantage, as you can hide implementation details and restrict access to certain classes. However, it can also limit reusability and lead to tight coupling if not used carefully.

Anonymous Inner Classes: Anonymous Inner Classes are a type of inner class, that doesn't have a name and is often used for event handling. They can be secure, but their scope is limited to where they are defined, making them useful only for specific scenarios.

2. Usefulness:

Encapsulation: Inner Classes can help achieve better encapsulation by keeping related classes together in one place. They are useful when you have a class that is tightly coupled to another class, and you want to group them logically.

Callback Mechanisms: Inner Classes are commonly used for implementing callback mechanisms, such as event listeners in graphical user interfaces. This makes your code more organized and easier to maintain.

Reducing Code Complexity: In some cases, using inner classes can lead to cleaner and more readable code. For example, if you have a class that is used only within another class and has no purpose outside of it, it can make sense to define it as an inner class to reduce code clutter.

Local Classes: Local classes (classes defined within methods) and anonymous inner classes can be useful for implementing small, one-time-use classes without cluttering the codebase.

(f) What are the two fundamental mechanisms for building a new classes of a existing class?

Ans- In Java, there are two fundamental mechanisms for building new classes based on existing classes: Inheritance and Composition.

1. Inheritance:

Definition: Inheritance is a mechanism that allows a new class (subclass or derived class) to inherit attributes and behaviours (fields and methods) from an existing class (superclass or base class). The new class can then extend or override these inherited attributes and behaviours, as well as add its own.

Syntax: To create a subclass that inherits from a superclass, you use the extends keyword in the class declaration.

Example:

class Animal {

void eat() {

System.out.println(Animal is eating.);

}

}

class Dog extends Animal {

void bark() {

System.out.println(Dog is barking.);

}

}

Use Cases: Inheritance is useful for creating a hierarchy of related classes, where common attributes and behaviours can be reused across multiple classes. It promotes code reusability and allows for polymorphism (objects of derived classes can be treated as objects of the base class).

2. Composition:

Definition: Composition is a mechanism that allows a class to be composed of one or more instances of other classes as objects. Instead of inheriting attributes and behaviours, a class can use objects of other classes to achieve its functionality.

Syntax: To use composition, you create instance variables (objects) of other classes within the class.

Example:

class Engine {

void start() {

System.out.println(Engine is starting.);

}

}

class Car {

private Engine engine = new Engine();

void startCar() {

engine.start();

System.out.println(Car is starting.);

}

}

Use Cases: Composition is useful when you want to build complex classes by combining simpler, reusable components. It promotes code modularity, flexibility, and the ability to change the behaviour of a class by changing the objects it is composed of.

The choice between inheritance and composition depends on the specific design requirements and goals of your application. In general, prefer composition when you want to create a more flexible and loosely coupled design, and use inheritance when you have a clear is-a relationship between the classes, indicating that one class is a specialized version of another. Both mechanisms have their advantages and trade-offs, and they can often be used together to create well-structured and maintainable software.

(g) The members of which classes can access members of a class in a particular package?

Ans- In Java, members (fields and methods) of a class can be accessed by other classes in the same package. This means that classes in the same package have what is called package-level or package-private access to each other's members.

Here are the rules for access control in Java:

Public Access (Public): Members marked as public can be accessed from anywhere, including classes in other packages.

Default Access (Package-Private Access): Members without any access modifier (i.e., no public, private, or protected modifier) are considered to have default access. They can be accessed only by classes within the same package. This means that members with default access are package-level accessible.

Private Access (Private): Members marked as private can only be accessed within the class in which they are declared. They are not accessible by other classes, even in the same package.

Protected Access (Protected): Members marked as protected can be accessed by classes in the same package and by subclasses (regardless of the package) that inherit from the class in which the protected member is defined.

(h) Why cannot the abstract method modifier be used together with the native modifier?

Ans- The abstract and native method modifiers in Java serve different purposes and are inherently incompatible because of their contrasting natures and requirements. Let's understand why they cannot be used together:

Abstract Method Modifier:

• The abstract modifier is used to declare an abstract method in a class. An abstract method is a method that has no implementation in the class where it's declared. It only provides a method signature, and its actual implementation is provided by a subclass that extends the abstract class.

• Abstract methods are meant to be overridden by subclasses, and they lack a method body. They exist to define a contract or an API that concrete subclasses must adhere to by providing their own implementations.

Native Method Modifier:

• The native modifier is used to declare a native method. A native method is a method for which the implementation is provided by code written in another programming language, typically in C or C++. It's used for interfacing Java with low-level platform-specific operations or external libraries.

• Native methods are used when you need to perform operations that are outside the scope of Java and the Java Virtual Machine (JVM). They are implemented externally and linked at runtime.

• The incompatibility between abstract and native arises from their implementation details:

Abstract methods have no implementation within the Java code; their purpose is to define a contract for subclasses to provide implementations.

• Native methods, on the other hand, have their implementation outside the Java code, and the JVM links to them at runtime.

Combining these two modifiers would create a contradiction because an abstract method is expected to be implemented by subclasses in Java, while a native method relies on external implementations that are typically not in Java. Therefore, using abstract and native together doesn't make sense and would lead to an ambiguous and problematic situation. In practice, you'll either declare a method as abstract or as native, depending on the intended use and implementation of the method, but not both.

2(a) Differentiate the following and support with example:

(i) Final and Static Member

Ans-

(ii) Inheritance and Aggregation

Ans-

(iii) Abstract Class and Interface

Ans-

(iv) String and String Buffer

Ans-

(b) Write a program to implement the following operations on a string :

(i) Convert to uppercase

Ans- Program to Convert a String to Uppercase:

public class StringToUppercase {

public static void main(String[] args) {

String originalString = Hello, World!;

// Convert to Uppercase

String uppercaseString = originalString.toUpperCase();

System.out.println(Original String: + originalString);

System.out.println(Uppercase String: + uppercaseString);

}

}

(ii) Convert to lowercase

Ans-

public class StringToLowercase {

public static void main(String[] args) {

String originalString = Hello, World!;

// Convert to Lowercase

String lowercaseString = originalString.toLowerCase();

System.out.println(Original String: + originalString);

System.out.println(Lowercase String: + lowercaseString);

}

}

(c) What is user-defined exceptions?

Ans- User-defined exceptions in Java (also known as custom exceptions) are exceptions that are created by the programmer to handle specific error conditions that may occur in their code. While Java provides a wide range of built-in exceptions to handle common error scenarios, there are situations where you may encounter unique errors that aren't adequately covered by the standard exception classes. In such cases, you can create your own exception classes by extending the Exception Class or one of its subclasses.

Here's how you can define a user-defined exception:

Create a Custom Exception Class: To create a custom exception, you define a new class that extends Exception, Runtime Exception, or any other exception class based on your requirements. You can also provide custom constructors and methods to suit your needs.

Throwing Custom Exceptions: In your code, when you encounter a specific error condition, you throw an instance of your custom exception using the throw keyword.

Catching Custom Exceptions: In the calling code or in an appropriate exception handling block (try-catch), you catch and handle your custom exception just like built-in exceptions.

Here's a simple example of a user-defined exception in Java:

class MyCustomException extends Exception {

public MyCustomException(String message) {

super(message);

}

}

public class CustomExceptionExample {

public static void main(String[] args) {

try {

int age = -5;

if (age < 0) {

throw new MyCustomException(Age cannot be negative.);

}

} catch (MyCustomException e) {

System.out.println(Custom Exception Caught: + e.getMessage());

}

}

}

3(a) What is the difference between checked and unchecked exceptions ?

Ans-

(b) Create a class account with the following data members

(i) account id

Ans-

public class Account {

private int accountId;

public Account(int accountId) {

this.accountId = accountId;

}

public int getAccountId() {

return accountId;

}

public void setAccountId(int accountId) {

this.accountId = accountId;

}

public static void main(String[] args) {

Account account = new Account(12345);

// Get the account ID

int id = account.getAccountId();

System.out.println(Account ID: + id);

// Update the account ID

account.setAccountId(54321);

System.out.println(Updated Account ID: + account.getAccountId());

}

}

In this example:

The Account class has a data member for account id.

The class provides a constructor to initialize the account ID when creating an Account object.

It also includes getter and setter methods (getAccountId and setAccountId) to retrieve and update the account ID, respectively.

The main method demonstrates how to create an Account object, get the account ID, and update it if needed.

(ii) name

Ans-

public class Account {

private String name;

public Account(String name) {

this.name = name;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public static void main(String[] args) {

Account account = new Account(John Doe);

// Get the account name

String accountName = account.getName();

System.out.println(Account Name: + accountName);

// Update the account name

account.setName(Alice Smith);

System.out.println(Updated Account Name: + account.getName());

}

}

In this example:

The Account class has a data member for name.

The class provides a constructor to initialize the name when creating an Account object.

It also includes getter and setter methods (getName and setName) to retrieve and update the account name, respectively.

The main method demonstrates how to create an Account object, get the account name, and update it if needed.

(iii) current balance

Ans-

public class Account {

private int accountId; // Account ID

private String name; // Account holder's name

private double currentBalance; // Current balance

public Account(int accountId, String name, double currentBalance) {

this.accountId = accountId;

this.name = name;

this.currentBalance = currentBalance;

}

public double getCurrentBalance() {

return currentBalance;

}

public void setCurrentBalance(double currentBalance) {

this.currentBalance = currentBalance;

}

public static void main(String[] args) {

Account account = new Account(12345, John Doe, 1000.0);

// Get the current balance

double balance = account.getCurrentBalance();

System.out.println(Current Balance: $ + balance);

// Update the current balance

account.setCurrentBalance(1500.0);

System.out.println(Updated Balance: $ + account.getCurrentBalance());

}

}

In this example:

The Account class has data members for account ID, name, and current balance.

The class provides a constructor to initialize these data members when creating an Account object.

It includes getter and setter methods (getCurrentBalance and setCurrentBalance) to retrieve and update the current balance.

The main method demonstrates how to create an Account object, get the current balance, and update it if needed.

And implement the member functions :

(i) Withdraw

Ans-

public class Account {S

private int accountId; // Account ID

private String name; // Account holder's name

private double currentBalance; // Current balance

public Account(int accountId, String name, double currentBalance) {

this.accountId = accountId;

this.name = name;

this.currentBalance = currentBalance;

}

public double getCurrentBalance() {

return currentBalance;

}

public void setCurrentBalance(double currentBalance) {

this.currentBalance = currentBalance;

}

public void withdraw(double amount) {

if (amount > 0 && amount <= currentBalance) {

currentBalance -= amount;

System.out.println(Withdrawal successful. New balance: $ + currentBalance);

} else {

System.out.println(Withdrawal failed. Invalid amount or insufficient balance.);

}

}

public static void main(String[] args) {

Account account = new Account(12345, John Doe, 1000.0);

// Get the current balance

double balance = account.getCurrentBalance();

System.out.println(Current Balance: $ + balance);

// Withdraw some amount

account.withdraw(500.0);

// Attempt to withdraw an invalid amount

account.withdraw(1500.0);

}

}

In this updated class

The withdraw method has been added to allow withdrawals from the account balance.

The method checks if the withdrawal amount is valid and if there are sufficient funds before performing the withdrawal operation. It then prints a message indicating whether the withdrawal was successful.

The main method demonstrates how to create an Account object, get the current balance, and perform a withdrawal operation using the withdraw method.

(ii) deposit

Ans-

public class Account {

private int accountId; // Account ID

private String name; // Account holder's name

private double currentBalance; // Current balance

public Account(int accountId, String name, double currentBalance) {

this.accountId = accountId;

this.name = name;

this.currentBalance = currentBalance;

}

public double getCurrentBalance() {

return currentBalance;

}

public void setCurrentBalance(double currentBalance) {

this.currentBalance = currentBalance;

}

public void deposit(double amount) {

if (amount > 0) {

currentBalance += amount;

System.out.println(Deposit successful. New balance: $ + currentBalance);

} else {

System.out.println(Deposit failed. Invalid amount.);

}

}

public static void main(String[] args) {

Account account = new Account(12345, John Doe, 1000.0);

// Get the current balance

double balance = account.getCurrentBalance();

System.out.println(Current Balance: $ + balance);

// Deposit some amount

account.deposit(500.0);

// Attempt to deposit an invalid amount

account.deposit(-200.0);

}

}

In this updated class

The deposit method has been added to allow deposits into the account balance.

The method checks if the deposit amount is valid (greater than zero) before performing the deposit operation. It then prints a message indicating whether the deposit was successful.

The main method demonstrates how to create an Account object, get the current balance, and perform a deposit operation using the deposit method.

(c) How multiple inheritance is achieved in Java? Explain with an example.

Ans- In Java, multiple inheritance, which is the ability to inherit from more than one class, is not supported for classes. However, Java provides a way to achieve a form of multiple inheritance through interfaces. In Java, a class can implement multiple interfaces, allowing it to inherit method signatures from multiple sources.

Here's an example to illustrate how multiple inheritance is achieved through interfaces in Java:

// Interface for Shape

interface Shape {

double getArea();

double getPerimeter();

}

// Interface for Color

interface Color {

String getColor();

}

// Class for Circle that implements Shape and Color

class Circle implements Shape, Color {

private double radius;

private String color;

public Circle(double radius, String color) {

this.radius = radius;

this.color = color;

}

@Override

public double getArea() {

return Math.PI * radius * radius;

}

@Override

public double getPerimeter() {

return 2 * Math.PI * radius;

}

@Override

public String getColor() {

return color;

}

}

public class Main {

public static void main(String[] args) {

Circle circle = new Circle(5.0, Red);

System.out.println(Circle Area: + circle.getArea());

System.out.println(Circle Perimeter: + circle.getPerimeter());

System.out.println(Circle Color: + circle.getColor());

}

}

In this example:

We define two interfaces, Shape and Color, each with a set of method signatures representing shape-related and color-related properties.

The Circle class implements both the Shape and Color interfaces. This allows it to provide concrete implementations for all the methods defined in these interfaces.

The Circle class has its own data members (radius and color) and provides concrete implementations for the getArea(), getPerimeter(), and getColor() methods defined in the interfaces.

In the main method, we create a Circle object and demonstrate how it can access methods from both the Shape and Color interfaces, effectively achieving multiple inheritance of method signatures.

(d) Write an applet that prints Here at the 9 current cursor position whenever the mouse left button is clicked.

Ans- To create a simple Java applet that prints Here at the current cursor position when the mouse left button is clicked, you can use the MouseListener interface and the MouseEvent class to detect mouse events. Here's an example of how to create this applet:

import java.applet.Applet;

import java.awt.event.MouseEvent;

import java.awt.event.MouseListener;

import java.awt.Graphics;

public class MouseClickApplet extends Applet implements MouseListener {

private String message = ;

@Override

public void init() {

addMouseListener(this); // Register the applet as a listener for mouse events

}

@Override

public void mouseClicked(MouseEvent e) {

int x = e.getX(); // Get the x-coordinate of the mouse click

int y = e.getY(); // Get the y-coordinate of the mouse click

message = Here;

repaint(); // Request a repaint to display the message at the clicked position

}

@Override

public void paint(Graphics g) {

g.drawString(message, 0, 0); // Display the message at (0, 0) on the applet

}

// Other unused methods from MouseListener interface

@Override

public void mousePressed(MouseEvent e) { }

@Override

public void mouseReleased(MouseEvent e) { }

@Override

public void mouseEntered(MouseEvent e) { }

@Override

public void mouseExited(MouseEvent e) { }

}

In this example:

We create a Java applet that implements the MouseListener interface to handle mouse events.

In the init method, we register the applet as a listener for mouse events using addMouseListener(this).

In the mouseClicked method, we retrieve the mouse click's coordinates using e.getX() and e.getY(), set the message to Here, and call repaint() to display the message at the clicked position.

In the paint method, we use the Graphics object to draw the message at the (0, 0) position on the applet.

We implement other unused methods from the MouseListener interface as required.

When you run this applet and click the left mouse button, it will display Here at the cursor's current position in the applet.

Example of Interthread Communication:

class SharedResource {

private boolean isDataReady = false;

synchronized void produce() {

// Produce data

isDataReady = true;

notify(); // Notify the consumer thread

}

synchronized void consume() {

if (!isDataReady) {

try {

wait(); // Wait until data is ready

} catch (InterruptedException e) {

Thread.currentThread().interrupt();

}

}

// Consume data

}

}

In this example, the produce method sets the is DataReady flag and notifies the consumer thread. The consume method checks, if the data is ready and, if not, it waits for the produce method to notify it when the data is available. This demonstrates the use of wait() and notify() for interthread communication.

(ii) Event Handling in Java

Ans- Event Handling in Java

Event handling is a fundamental aspect of Java programming, especially in graphical user interfaces (GUI) and other interactive applications. It allows a program to respond to various events, such as user actions (e.g., mouse clicks, keypresses), system events, or custom events, and execute appropriate code in response to those events.

Here are key concepts related to event handling in Java:

Event Source: An Event Source is an object or component (e.g., a button, a text field, or a window) that can generate events. The source object triggers events when specific actions occur.

Event Listener: An Event Listener is an object that listens for events from one or more event sources. Event listeners are responsible for handling events when they occur. In Java, event listeners are typically implemented as interfaces with event-handling methods.

Event Object: When an event occurs, an Event Object is created to encapsulate information about the event, such as the source of the event and the type of event. Event objects are then passed to the appropriate event listeners.

Event Handler: An Event Handler is a method or code block that responds to a specific type of event. Event handlers are typically defined within event listener implementations.

Event Types: Java provides a wide range of Event Types, including ActionEvents (e.g., button clicks), MouseEvents (e.g., mouse clicks or movements), KeyEvents (e.g., key presses), WindowEvents (e.g., window opening or closing), and more. You can also create custom events by extending Java's event classes.

Event Registration: To establish a connection between an event source and an event listener, you must register the listener with the source. This is typically done using addXXXListener methods provided by the source.

Event Dispatch Thread (EDT): In GUI applications, event handling often occurs on a dedicated thread called the Event Dispatch Thread. This thread is responsible for processing and dispatching events to their respective listeners. GUI components should only be accessed and modified on the EDT to ensure thread safety.

(b)What is a Layout Manager? Explain layouts with example.

Ans- Layout Managers in Java are a crucial part of building graphical user interfaces (GUIs) for applications. They control how components (such as buttons, labels, text fields, etc.) are arranged within a container (e.g., a window or a panel). Layout managers ensure that the components are displayed in an organized and consistent way, adapting to various window sizes and screen resolutions.

Java provides several built-in layout managers, each with its own way of arranging components. Some of the common layout managers are:

FlowLayout: Components are arranged from left to right, and if the horizontal space runs out, they wrap to the next line.

BorderLayout: Components are arranged in five regions: North, South, East, West, and Center. The Center region expands to occupy the remaining space.

GridLayout: Components are arranged in a grid with a fixed number of rows and columns.

GridBagLayout: Provides a more flexible grid arrangement, allowing components to span multiple rows and columns.

BoxLayout: Components are laid out either vertically or horizontally in a single line.

CardLayout: Allows multiple components to be placed on top of each other, and you can switch between them.

SpringLayout: A flexible layout manager that can handle complex component constraints.

NullLayout: Allows absolute positioning of components, but it's generally not recommended for complex GUIs.

Example of Layouts:

Let's take an example using GridLayout and FlowLayout layout managers to arrange buttons in a simple GUI. We'll create a window with buttons using both layout managers:

import javax.swing.*;

import java.awt.*;

public class LayoutExample {

public static void main(String[] args) {

JFrame frame = new JFrame(Layout Example);

// Using GridLayout

JPanel gridPanel = new JPanel(new GridLayout(3, 2));

gridPanel.add(new JButton(Button 1));

gridPanel.add(new JButton(Button 2));

gridPanel.add(new JButton(Button 3));

gridPanel.add(new JButton(Button 4));

gridPanel.add(new JButton(Button 5));

gridPanel.add(new JButton(Button 6));

// Using FlowLayout

JPanel flowPanel = new JPanel(new FlowLayout());

flowPanel.add(new JButton(Button A));

flowPanel.add(new JButton(Button B));

flowPanel.add(new JButton(Button C));

flowPanel.add(new JButton(Button D));

frame.add(gridPanel, BorderLayout.NORTH);

frame.add(flowPanel, BorderLayout.SOUTH);

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

frame.setSize(300, 200);

frame.setVisible(true);

}

}

In this example:

We create a JFrame (window) and add two JPanel components with different layout managers: GridLayout and FlowLayout.

In the GridLayout, buttons are arranged in a 3x2 grid, and in the FlowLayout, buttons are arranged horizontally.

By combining these layout managers within the JFrame, you can see how components are arranged in the window. Different layouts help control the positioning and resizing of components within the GUI, adapting to different window sizes and orientations.

(c) Write a Java program to set up JDBC and execute the following SQL statement on a database table employee-t with the fields emp-id, emp name, emp-department, emp-basic "SELECT * FROM employee-t where emp-basic < 10000;

Ans- To execute an SQL statement on a database table using JDBC in Java, you need to follow these steps:

• Load the JDBC driver.

• Establish a database connection.

• Create a Statement or PreparedStatement to execute the SQL query.

• Execute the SQL query.

• Process the query result.

Here's a Java program that demonstrates how to execute the SQL statement you provided on a database table named employee_t:

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.Statement;

public class JDBCSQLQuery {

public static void main(String[] args) {

// Database connection details

String jdbcUrl = jdbc:mysql://localhost:3306/your_database_name;

String dbUser = your_username;

String dbPassword = your_password;

try {

// Step 1: Load the JDBC driver

Class.forName(com.mysql.cj.jdbc.Driver);

// Step 2: Establish a database connection

Connection connection = DriverManager.getConnection(jdbcUrl, dbUser, dbPassword);

// Step 3: Create a Statement to execute the SQL query

Statement statement = connection.createStatement();

// Step 4: Execute the SQL query

String sqlQuery = SELECT * FROM employee_t WHERE emp-basic < 10000;;

ResultSet resultSet = statement.executeQuery(sqlQuery);

// Step 5: Process the query result

while (resultSet.next()) {

int empId = resultSet.getInt(emp-id);

String empName = resultSet.getString(emp-name);

String empDepartment = resultSet.getString(emp-department);

double empBasic = resultSet.getDouble(emp-basic);

System.out.println(Employee ID: + empId);

System.out.println(Employee Name: + empName);

System.out.println(Employee Department: + empDepartment);

System.out.println(Employee Basic Salary: + empBasic);

System.out.println();

}

// Step 6: Close the resources

resultSet.close();

statement.close();

connection.close();

} catch (Exception e) {

e.printStackTrace();

}

}

}

Make sure to replace your_database_name, your_username, and your_password with your actual database details, and use the appropriate JDBC driver for your database. This example assumes you're using MySQL as the database.

5(a) Write a program to sort the list given as command line arguments using bubble sort.

Ans- Java program that sorts a list of integers using the Bubble Sort Algorithm. You can provide the list of integers as command-line arguments, and the program will sort them in ascending order:

public class BubbleSort {

public static void main(String[] args) {

if (args.length == 0) {

System.out.println(Please provide a list of integers as command-line arguments.);

return;

}

int[] arr = new int[args.length];

for (int i = 0; i < args.length; i++) {

try {

arr[i] = Integer.parseInt(args[i]);

} catch (NumberFormatException e) {

System.out.println(Invalid input: + args[i] + is not an integer.);

return;

}

}

System.out.println(Original List:);

printArray(arr);

bubbleSort(arr);

System.out.println(Sorted List:);

printArray(arr);

}

public static void bubbleSort(int[] arr) {

int n = arr.length;

boolean swapped;

for (int i = 0; i < n - 1; i++) {

swapped = false;

for (int j = 0; j < n - i - 1; j++) {

if (arr[j] > arr[j + 1]) {

// Swap arr[j] and arr[j+1]

int temp = arr[j];

arr[j] = arr[j + 1];

arr[j + 1] = temp;

swapped = true;

}

}

if (!swapped) {

// If no two elements were swapped, the list is already sorted.

break;

}

}

}

public static void printArray(int[] arr) {

for (int num : arr) {

System.out.print(num + );

}

System.out.println();

}

}

To run the program, open your command prompt or terminal, navigate to the directory where you've saved the Java file, and execute the program with a list of integers as command-line arguments. For example: java BubbleSort 5 2 9 1 5 6

This will sort the provided list of integers using the Bubble Sort algorithm and print the sorted list.

(b) What is Java Bean? What are its advantages?

Ans- JavaBean is a reusable software component in Java that follows certain conventions and guidelines, making it easy to integrate into various Java-based applications and development tools. JavaBeans are used to encapsulate and manage the