additional topics

// code by zain
import java.time.LocalDateTime;                 // recieves LocalDateTime class from java.time package
import java.time.format.DateTimeFormatter;      // recieves DateTimeFormatter from java.time.format package
import java.util.*;                             // provides access to arrays
import java.util.Date;
import java.io.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
import java.text.SimpleDateFormat;              // recieves from java.text package

// recieving/ publishing time and date version 1
public static String getCurrentTime(){             // Method declaration for getting current time as a string

    SimpleDateFormat dateFormat = new SimpleDateFormat(    // Creating a SimpleDateFormat object for formatting date and time
            "dd-MMM-yyyy HH:mm:ss");
   
    long timestamp = System.currentTimeMillis();           // Getting current time in milliseconds
    
    Date date=new Date(timestamp);                      // Creating a Date object using the timestamp
    
    String timestampStr = dateFormat.format(date);   
    
    return timestampStr;                                 // Returning the formatted date and time as a string
    
    }

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   // code from here onwards was not used in main mqtt project
   
   // recieving/ publishing time and date version 2
public class Main {                                     // Define public class

    public static void publishTimeDateLocation(String client, String currentLocation) {   // Defining method to publish current time, date, and location
        
        LocalDateTime now = LocalDateTime.now();                                   // Getting current date and time
       
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern ("yyyy-MM-dd HH:mm:ss");   //defining formatter to format the date and time
        
        String currentTimeDate = now.format(formatter);           // Format the current date and time using the defined formatter

        
        String message = "Date: " + currentTimeDate + ", Location: " + currentLocation;  // writing a message for output of time, date and location

        
        System.out.println("Publishing to topic: 'TIME, DATE AND LOCATION'");   // Printing message showing publishing to "TIME, DATE AND LOCATION" topic
        
        System.out.println(message);
    }

    public static void main(String[] args) {                                     // main method
        
        // Example of output:
        publishTimeDateLocation("client", "Coventry");
    }
}

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// getting time date and location updates

public class Main {                                         // defining public class

    // Handling time updates
    public static void handleTimeUpdate(String time) {      // Defining method to handle time updates
        
        System.out.println("Time update: " + time);         // Printing message indicating a time update
    }

    // Handling date updates
    public static void handleDateUpdate(String date) {       // Defining method to handle date updates
        
        System.out.println("Date update: " + date);          // Printing message indicating a date update
    }

    // Handling location updates
    public static void handleLocationUpdate(String location) {   // Defining method to handle location updates
        
        System.out.println("Location update: " + location);      // Printing message indicating a location update
    }

    public static void main(String[] args) {                    // main method
        
        // Example output:
        String currentTime = "12:00 PM";                        // output current time/date/location
        
        String currentDate = "2024-03-21";
        
        String currentLocation = "Birmingham";

        // Publishing the updates
        handleTimeUpdate(currentTime);
        
        handleDateUpdate(currentDate);
        
        handleLocationUpdate(currentLocation);
    }
}
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//error handling techniques



public class MessagingProtocol {                           // defining public class named MessagingProtocol
    
    static final String BROKER_URL = "tcp://mqtt.eclipseprojects.io:1883";            // Define constants for broker URL and topic
    
    static final String TOPIC = "MESSAGE";

    public static void main(String[] args) {               // Main method
        try {
            BrokerConnection();                            // connecting to broker
        } catch (Exception e) {
            handleException(e);                            //// Handling any exceptions that occur during connection establishment
        }
    }

    private static void BrokerConnection() {               // Method for establishing connection to broker
        
        System.out.println("Connected to broker.");        // message showing connection to a broker

        System.out.println("Subscribed to topic: " + TOPIC);  // message showing subscription to a topic

        // Keeping the program running
        while (true) {
        }
    }
    // Handling exceptions and outputting results
    private static void handleException(Exception e) {
        
        System.err.println("An exception occurred: " + e.getMessage());
    }
}

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//priority levels for messages

public class MessagePriorityPublisher {                     // defining public class called MessagePriorityPublisher
    
    private static final String TOPIC = "PRIORITY_TOPIC";   // Defining constant for the topic to publish messages

    public static void main(String[] args) {                // main method
        try {
            // Loop indefinitely to continuously publish messages
            while (true) {
                // Generating new message
                String message = createMessage();
                
                int priority = determinePriorityLevel();    // Determining the priority level of the message

                
                // Adjusting Quality of Service (QoS) level based on the priority level
                int qos = adjustQoSLevel(priority);
                // Publishing message with its according priority level
                System.out.println("Published '" + message + "' to Topic " + TOPIC + " with Priority level " + priority);

                // Sleep for some time before publishing next message
                Thread.sleep(6000);
            }
        } catch (InterruptedException e) {             // Printing the stack trace if thread is interrupted
            e.printStackTrace();
        }
    }

    private static String createMessage() {
        // Adding logic to get the message content
        return "New message recieved at " + getCurrentTime();
    }

    private static int determinePriorityLevel() {
        // Adding logic to determine the priority level 
        // For example, return a value between 0 and 2 for the priority level
        return (int) (Math.random() * 3);
    }

    private static int adjustQoSLevel(int priority) {
        // Adjusting the QoS level based on the priority level
        switch (priority) {
            case 0:
                return 0; // Lowest priority level, QOS 0
            
            case 1:
                return 1; // Medium priority level, QOS 1
            
            case 2:
                return 2; // Highest priority level, QOS 2
            
            default:
                return 1; // Default to QOS 1 if priority level is not retained
        }
    }

    private static String getCurrentTime() {                   // Method to get current time 
        
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");   // Create a SimpleDateFormat object with desired date format
        
        return dateFormat.format(new Date());   // Getting current date and time formatted according to the SimpleDateFormat
    }
}