import java.util.Scanner;
  class PalindromeCheck {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      System.out.print("Enter a number: ");
      int num = sc.nextInt();
      int original = num;
      int reverse = 0;
      while (num != 0) {
        reverse = reverse * 10 + num % 10;
        num /= 10;
      }
      if (original == reverse) {
        System.out.println("The number is a palindrome.");
      } else {
        System.out.println("The number is not a palindrome.");
      }
    }
  }
          

            import java.util.Scanner;
  class ArmstrongCheck {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      System.out.print("Enter a number: ");
      int num = sc.nextInt();
      int original = num;
      int sum = 0;
      while (num != 0) {
        int digit = num % 10;
        sum += digit * digit * digit;
        num /= 10;
      }
      if (original == sum) {
        System.out.println("The number is an Armstrong number.");
      } else {
        System.out.println("The number is not an Armstrong number.");
      }
    }
  }
          

            import java.util.Scanner;
  class PrimeCheck {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      System.out.print("Enter a number: ");
      int num = sc.nextInt();
      boolean isPrime = true;
      if (num <= 1) {
        isPrime = false;
      } else {
        for (int i = 2; i <= Math.sqrt(num); i++) {
          if (num % i == 0) {
            isPrime = false;
            break;
          }
        }
      }
      if (isPrime) {
        System.out.println("The number is prime.");
      } else {
        System.out.println("The number is not prime.");
      }
    }
  }
          

            import java.util.Scanner;
  class FibonacciSeries {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      System.out.print("Enter the number of terms: ");
      int n = sc.nextInt();
      int a = 0, b = 1;
      System.out.print("Fibonacci series: " + a + ", " + b);
      for (int i = 2; i < n; i++) {
        int next = a + b;
        System.out.print(", " + next);
        a = b;
        b = next;
      }
      System.out.println();
    }
  }
          

            import java.util.Scanner;
  class SumAndAverage {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int[] numbers = new int[10];
      System.out.println("Enter 10 numbers:");
      int sum = 0;
      for (int i = 0; i < 10; i++) {
        numbers[i] = sc.nextInt();
        sum += numbers[i];
      }
      double average = sum / 10.0;
      System.out.println("Sum: " + sum);
      System.out.println("Average: " + average);
    }
  }
          

            import java.util.Scanner;
  class BubbleSort {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int[] numbers = new int[10];
      System.out.println("Enter 10 numbers:");
      for (int i = 0; i < 10; i++) {
        numbers[i] = sc.nextInt();
      }
      for (int i = 0; i < numbers.length - 1; i++) {
        for (int j = 0; j < numbers.length - 1 - i; j++) {
          if (numbers[j] > numbers[j + 1]) {
            int temp = numbers[j];
            numbers[j] = numbers[j + 1];
            numbers[j + 1] = temp;
          }
        }
      }
      System.out.println("Sorted numbers in ascending order:");
      for (int num : numbers) {
        System.out.print(num + " ");
      }
      System.out.println();
    }
  }
          

          import java.util.Scanner;
class LinearSearch {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    System.out.print("Enter the size of the array: ");
    int n = sc.nextInt();
    int[] array = new int[n];
    System.out.println("Enter " + n + " sorted elements:");
    for (int i = 0; i < n; i++) {
      array[i] = sc.nextInt();
    }
    System.out.print("Enter the element to search: ");
    int target = sc.nextInt();
    boolean found = false;
    for (int i = 0; i < n; i++) {
      if (array[i] == target) {
        System.out.println("Element found at index " + i);
        found = true;
        break;
      }
    }
    if (!found) {
      System.out.println("Element not found in the array.");
    }
  }
}
        

          import java.util.Scanner;
class MatrixAddition {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[][] matrix1 = new int[2][2];
    int[][] matrix2 = new int[2][2];
    int[][] sum = new int[2][2];

    System.out.println("Enter elements of first 2x2 matrix:");
    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < 2; j++) {
        matrix1[i][j] = sc.nextInt();
      }
    }

    System.out.println("Enter elements of second 2x2 matrix:");
    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < 2; j++) {
        matrix2[i][j] = sc.nextInt();
      }
    }

    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < 2; j++) {
        sum[i][j] = matrix1[i][j] + matrix2[i][j];
      }
    }

    System.out.println("Sum of the matrices:");
    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < 2; j++) {
        System.out.print(sum[i][j] + " ");
      }
      System.out.println();
    }
  }
}
        

          import java.util.Scanner;
class MatrixMultiplication {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int[][] matrix1 = new int[2][2];
    int[][] matrix2 = new int[2][2];
    int[][] product = new int[2][2];

    System.out.println("Enter elements of first 2x2 matrix:");
    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < 2; j++) {
        matrix1[i][j] = sc.nextInt();
      }
    }

    System.out.println("Enter elements of second 2x2 matrix:");
    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < 2; j++) {
        matrix2[i][j] = sc.nextInt();
      }
    }

    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < 2; j++) {
        product[i][j] = 0;
        for (int k = 0; k < 2; k++) {
          product[i][j] += matrix1[i][k] * matrix2[k][j];
        }
      }
    }

    System.out.println("Product of the matrices:");
    for (int i = 0; i < 2; i++) {
      for (int j = 0; j < 2; j++) {
        System.out.print(product[i][j] + " ");
      }
      System.out.println();
    }
  }
}
        

          class Student {
  String name;
  int age;

  void displayInfo() {
    System.out.println("Name: " + name);
    System.out.println("Age: " + age);
  }

  public static void main(String[] args) {
    Student student = new Student();
    student.name = "John";
    student.age = 20;
    student.displayInfo();
  }
}
        

          class Calculator {
  int add(int a, int b) {
    return a + b;
  }

  double add(double a, double b) {
    return a + b;
  }

  public static void main(String[] args) {
    Calculator calc = new Calculator();
    System.out.println("Sum (int): " + calc.add(10, 20));
    System.out.println("Sum (double): " + calc.add(5.5, 4.5));
  }
}
        

          class Rectangle {
  int length, breadth;

  Rectangle() {
    length = 0;
    breadth = 0;
  }

  Rectangle(int l, int b) {
    length = l;
    breadth = b;
  }

  int area() {
    return length * breadth;
  }

  public static void main(String[] args) {
    Rectangle rect1 = new Rectangle();
    Rectangle rect2 = new Rectangle(5, 10);
    System.out.println("Default area: " + rect1.area());
    System.out.println("Parameterized area: " + rect2.area());
  }
}
        

          class Animal {
  void sound() {
    System.out.println("Animals make sound");
  }
}

class Dog extends Animal {
  void sound() {
    System.out.println("Dogs bark");
  }

  public static void main(String[] args) {
    Dog dog = new Dog();
    dog.sound();
  }
}
        

a. Single try with single catch

          public class ExceptionDemo {
    public static void main(String[] args) {
        try {
            int result = 10 / 0;  // This will throw an ArithmeticException
        } catch (ArithmeticException e) {
            System.out.println("Error: " + e);
        }
    }
}
        
        

b. Single try with multiple catches java

          public class ExceptionDemo {
public static void main(String[] args) {
    try {
        int[] arr = new int[2];
            arr[3] = 10;  // This will throw an ArrayIndexOutOfBoundsException
            int result = 10 / 0;  // This will throw an ArithmeticException
        } catch (ArithmeticException e) {
            System.out.println("Arithmetic Error: " + e);
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Array Index Error: " + e);
        }
    }
}
        
        

c. Multiple try blocks with a single catch

          public class ExceptionDemo {
public static void main(String[] args) {
    try {
            int result = 10 / 0;  // This will throw an ArithmeticException
        } catch (ArithmeticException e) {
            System.out.println("Error: " + e);
        }
        
    try {
            String str = null;
            System.out.println(str.length());  // This will throw a NullPointerException
        } catch (Exception e) {
            System.out.println("Error: " + e);
        }
    }
}        
        
        

d. Multiple try blocks with multiple catches

          public class ExceptionDemo {
public static void main(String[] args) {
    try {
            int result = 10 / 0;  // This will throw an ArithmeticException
        } catch (ArithmeticException e) {
            System.out.println("Arithmetic Error: " + e);
        }        
    try {
            int[] arr = new int[2];
            arr[3] = 10;  // This will throw an ArrayIndexOutOfBoundsException
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Array Index Error: " + e);
        }
    }
}               
        
        

          // Interface
interface Animal {
    void sound(); // Abstract method
    void sleep(); // Abstract method
      }
            
    // Concrete class implementing the interface
    class Dog implements Animal {
        @Override
            public void sound() {
                System.out.println("Woof Woof");
            }
            
        @Override
            public void sleep() {
                System.out.println("Dog is sleeping.");
            }
        }
            
    class Cat implements Animal {
        @Override
            public void sound() {
                System.out.println("Meow");
            }
            
        @Override
            public void sleep() {
                System.out.println("Cat is sleeping.");
            }
        }
            
            public class InterfaceDemo {
            public static void main(String[] args) {
                Animal dog = new Dog();
                 dog.sound();
                 dog.sleep();
            
                Animal cat = new Cat();
                 cat.sound();
                 cat.sleep();
                }
            }
            
            

          // In package animals
package animals;
  public class Dog {
    public void sound() {
        System.out.println("Woof Woof");
        }
    }
            
// In package test
package test;
     import animals.Dog;        
     public class PackageDemo {
        public static void main(String[] args) {
            Dog dog = new Dog();
            dog.sound();
        }
    }
            
            
            

          // Extending Thread class
class MyThread extends Thread {
    @Override
     public void run() {
      for (int i = 1; i <= 5; i++) {
        try {
          Thread.sleep(1000);
            System.out.println(Thread.currentThread().getId() + " Value " + i);
        } catch (InterruptedException e) {
            System.out.println(e);
        }
    }
 }
}
           
     public class MultiThreadingDemo {
        public static void main(String[] args) {
            MyThread thread1 = new MyThread();
            MyThread thread2 = new MyThread();
            thread1.start();  // Start thread1
            thread2.start();  // Start thread2
        }
    }            
            
            

          import java.sql.*;

  public class OracleJDBCExample {
            
      public static void main(String[] args) {
            try {
                // Load the Oracle Type 2 driver (OCI driver)
                // The Oracle OCI driver uses the Oracle Client libraries to connect to the Oracle DB
                Class.forName("oracle.jdbc.OracleDriver");
                System.out.println("Driver Loaded Successfully!");
            
                // Establish a connection using Type 2 driver (OCI)
                // You must have the Oracle client (OCI) installed and configured
                Connection conn = DriverManager.getConnection(
                "jdbc:oracle:oci8:@localhost:1521:orcl", // JDBC URL for OCI driver
                "username",  // Replace with your Oracle username
                "password"   // Replace with your Oracle password
                );
                System.out.println("Connection Established Successfully!");
            
                // Create a statement
                Statement stmt = conn.createStatement();
            
                // Execute a query
                String query = "SELECT id, Name FROM students"; // SQL query to retrieve student data
                ResultSet rs = stmt.executeQuery(query);
            
                // Process the result set
                while (rs.next()) {
                    System.out.println("ID = " + rs.getInt("id") + ", Name = " + rs.getString("Name"));
                }
            
                // Close resources
                rs.close();
                stmt.close();
                conn.close();
                    System.out.println("Connection Closed Successfully!");
                } catch (Exception e) {
                    System.out.println("Something went wrong: " + e.getMessage());
                }
          }
    }
            
            
            

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
  <%@ page import="java.io.*, javax.servlet.*, javax.servlet.http.*" %>
  <html>
  <head>
      <title>Login Page</title>
  </head>
  <body>
      <h2>Login Form</h2>
      <form action="LoginServlet" method="post">
          <label for="username">Username:</label><br>
          <input type="text" id="username" name="username" required><br><br>
  
          <label for="password">Password:</label><br>
          <input type="password" id="password" name="password" required><br><br>
  
          <button type="submit">Login</button>
      </form>
  </body>
  </html>
  

            

            import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Set response content type
        response.setContentType("text/html");

        // Get the user input from the login form
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        // Logic to validate the credentials (For simplicity, using hardcoded values)
        PrintWriter out = response.getWriter();
        if ("admin".equals(username) && "password123".equals(password)) {
            // If valid, redirect to a welcome page
            out.println("
Welcome, " + username + "!
");
            out.println("
You have logged in successfully.
");
        } else {
            // If invalid, send an error message
            out.println("
Invalid login credentials.
");
            out.println("
Try again
");
        }
    }
}           
      
            
              

    import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
      
  public class UserServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
    throws ServletException, IOException {
      response.setContentType("text/html");
      PrintWriter out = response.getWriter();
      
      try {
            // Connect to the database
            Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", 
            "root", "password");
      
            // Fetch the first 5 users
            String query = "SELECT id, username, password FROM users LIMIT 5";
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery(query);
      
            // Start HTML output
            out.println("<html><body>");
            out.println("<h2>User Details</h2>");
            out.println("<table border='1'><tr><th>ID</th><th>Username</th><th>Password</th></tr>");

      
            // Loop through the result set and display data in a table
            while (rs.next()) {
              out.println("<tr>");
                out.println("<td>" + rs.getInt("id") + "</td>");
                out.println("<td>" + rs.getString("username") + "</td>");
                out.println("<td>" + rs.getString("password") + "</td>");
                out.println("</tr>");
          }
          out.println("</table>");
          out.println("</body></html>");
      
            // Close resources
            rs.close();
            stmt.close();
            conn.close();
          } catch (Exception e) {
              out.println("Error: " + e.getMessage());
          }
        }
    }
      
      
      

    <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@ page import="java.sql.*, java.util.*" %>
<html>
<head>
    <title>User Details</title>
    <style>
        table {
            width: 50%;
            margin: 50px auto;
            border-collapse: collapse;
        }
        th, td {
            padding: 8px;
            text-align: left;
            border: 1px solid #ddd;
        }
        th {
            background-color: #f2f2f2;
        }
    </style>
</head>
<body>
    <h2 style="text-align: center;">User Details</h2>
    <table>
    <thead>
        <tr>
            <th>ID</th>
            <th>Username</th>
            <th>Password</th>
        </tr>
    </thead>
    <tbody>
            <%
            // Establish the database connection using the utility class
            Connection conn = null;
            Statement stmt = null;
            ResultSet rs = null;
            
            try {
                conn = DBConnection.getConnection(); // Use the DBConnection class
                stmt = conn.createStatement();
                
                // Query to fetch first 5 users from the database
                String query = "SELECT id, username, password FROM users LIMIT 5";
                rs = stmt.executeQuery(query);
                
                // Loop through the result set and display user data in the table
                while (rs.next()) {
                  out.println("<tr>");
                  out.println("<td>" + rs.getInt("id") + "</td>");
                  out.println("<td>" + rs.getString("username") + "</td>");
                  out.println("<td>" + rs.getString("password") + "</td>");
                  out.println("</tr>");
                }
            } catch (SQLException e) {
                out.println("<tr><td colspan='3'>Error: " + e.getMessage() + "</td></tr>");
            } finally {
                // Close the database resources
                try {
                  if (rs != null) rs.close();
                  if (stmt != null) stmt.close();
                  if (conn != null) conn.close();
                } catch (SQLException e) {
                  out.println("<tr><td colspan='3'>Error closing resources: " + 
                  e.getMessage() + "</td></tr>");
                }
            }
            %>
        </tbody>
    </table>
</body>
</html>
      
      
      

          import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.text.*;

public class CookieServlet extends HttpServlet {
    
    private static final String LOG_FILE_PATH = "C:/logs/application.log"; 
    // Change this path based on your system

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) 
    throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        
        // Create a new cookie
        String userId = UUID.randomUUID().toString(); // Generate a unique user ID
        Cookie userCookie = new Cookie("userID", userId);
        userCookie.setMaxAge(60 * 60); // Set cookie expiration to 1 hour
        response.addCookie(userCookie);

        // Log the request information
        logRequestToFile(request);

        out.println("<html>");
        out.println("<body>");
        out.println("<h2>Cookie Created Successfully!</h2>");
        out.println("<p>Your unique user ID (Cookie): " + userId + "</p>");
        out.println("<p><a href='log.jsp'>Click here to view the log file</a></p>");
        out.println("</body>");
        out.println("</html>");
    }

    // Method to log request information into a log file
    private void logRequestToFile(HttpServletRequest request) {
        try {
          PrintWriter logWriter = new PrintWriter(new FileWriter(LOG_FILE_PATH, true)); // Append mode
          String timestamp = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
          String logMessage = timestamp + " - Access from IP: " + request.getRemoteAddr() 
          + " with User-Agent: " + request.getHeader("User-Agent");
          logWriter.println(logMessage);
          logWriter.close();
        } catch (IOException e) {
          System.out.println("Error logging request: " + e.getMessage());
        }
    }
}
          
        

              <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ page import="java.io.*, java.util.*" %>
<html>
<head>
    <title>Log File and Cookie Information</title>
</head>
<body>
    <h2>Cookie Information</h2>
    <p>
        <%
            Cookie[] cookies = request.getCookies();
            if (cookies != null) {
                for (Cookie cookie : cookies) {
                    if ("userID".equals(cookie.getName())) {
                        out.println("Your User ID (Cookie): " + cookie.getValue());
                    }
                }
            } else {
                out.println("No cookies found.");
            }
        %>
    </p>

    <h2>Log File Contents</h2>
    <pre>
        <%
            String logFilePath = "C:/logs/application.log"; 
            // Make sure the path is correct for your environment
            File logFile = new File(logFilePath);
            if (logFile.exists()) {
                BufferedReader reader = new BufferedReader(new FileReader(logFile));
                String line;
                while ((line = reader.readLine()) != null) {
                    out.println(line);
                }
                reader.close();
            } else {
                out.println("Log file does not exist.");
            }
        %>
    </pre>
</body>
</html>