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Java Programming [ Lab Programs ]

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Aim:

Source Code:

ExceptionsDemo.java

import java.io.File;

import java.io.FileReader;

import java.io.FileNotFoundException;



// Custom Exception

class InvalidAgeException extends Exception {

    public InvalidAgeException(String message) {

        super(message);

    }

}



public class ExceptionsDemo {

     // Method to demonstrate custom exception

    public static void register(String name, int age) throws InvalidAgeException {

        if (age < 18) {

            throw new InvalidAgeException("User must be at least 18 years old.");

        } else {

            System.out.println("Registration successful for user: " + name);

        }

    }

    public static void main(String[] args) {

        //Handling Checked Exception 

        try {

            File file = new File("myfile.txt");

            // This line can throw FileNotFoundException

            FileReader fr = new FileReader(file);     

        } catch (FileNotFoundException e) {

            System.out.println("File not found: " + e.getMessage());

        }

        //Handling Unchecked Exception 

        try {

            int[] arr = {1, 2, 3};

            // Accessing an out-of-bound index

            System.out.println(arr[6]); 

        } catch (ArrayIndexOutOfBoundsException e) {

            System.out.println("Array index out of bounds: " + e.getMessage());

        }

        // Finally block to perform cleanup operations

        finally {

            System.out.println("Cleanup operations can be performed here.");

        }

        // Demonstrate custom exception handling

        System.out.println("Demonstrating Custom Exception:");

        try {

            // Invalid age for registration

            register("Madhu", 17); 

        } catch (InvalidAgeException e) {

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

        }

    }

}

Output:

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Java Programming Lab Programs

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2) Write a Java program to demonstrate the OOP principles. [i.e., Encapsulation, Inheritance, Polymorphism and Abstraction] View Solution

3) Write a Java program to handle checked and unchecked exceptions. Also, demonstrate the usage of custom exceptions in real time scenario. View Solution

4) Write a Java program on Random Access File class to perform different read and write operations. View Solution

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9) Write a Java program that handles all mouse events and shows the event name at the center of the window when a mouse event is fired. [Use Adapter classes] View Solution

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