A Brief Introduction of Using Java Logger

import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * @author Hank Lee
 * Shared in InformisTry -- https://jumperc2p.github.io/InformisTry/
 *
 */
public class MyLogger {

	public static void main(String[] args) {
		
		// use the method "getLogger(String name)" in Logger class to get a Logger object
		Logger logger = Logger.getLogger("MyLogger"); 
		
		// set the level of the logger as INFO
		logger.setLevel(Level.INFO);
		
		// use java.util.Random to receive a random number
		Random random = new Random();
		
		//setup a range to random number
		int range = 50;
		
		while (true) {
			// get a random number
			int number = random.nextInt(range);
			
			logger.log(Level.INFO, "The random number is :" + number);
			
			// when the remainder of random number divided 7 is 0 , stop the while loop.
			if (number % 7 == 0) {
				break;
			}
		}
	}
}

package logging_example;

import java.io.IOException;
import java.util.Random;
import java.util.logging.FileHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;

/**
 * @author Hank Lee
 * Shared in InformisTry -- https://jumperc2p.github.io/InformisTry/
 *
 */
public class MyLoggerWithFileOutput {

	public static void main(String[] args) {
		
		// use the method "getLogger(String name)" in Logger class to get a Logger object
		Logger logger = Logger.getLogger("MyLogger"); 
		
		// Declare a FileHandler variable.
		FileHandler fh;
		
		// set the level of the logger as INFO
		logger.setLevel(Level.INFO);
		
		try {
			// create a new FileHandler object with the log file path
			fh = new FileHandler(System.getProperty("user.dir")+"/informistry.log");
			
			// create a SimpleFormatter object to setup the format of log
			SimpleFormatter formatterFH = new SimpleFormatter();  
			// set the SimpleFormatter to the FileHandler
			fh.setFormatter(formatterFH); 
			
			// add the FileHandler to the logger
			logger.addHandler(fh);
			
			// use java.util.Random to receive a random number
			Random random = new Random();
			
			//setup a range to random number
			int range = 50;
			
			while (true) {
				// get a random number
				int number = random.nextInt(range);
				
				logger.log(Level.INFO, "The random number is :" + number);
				
				// when the remainder of random number divided 7 is 0 , stop the while loop.
				if (number % 7 == 0) {
					break;
				}
			}
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}  
	}
}

import java.io.IOException;
import java.util.logging.FileHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;

/**
 * @author Hank Lee
 * Shared in InformisTry -- https://jumperc2p.github.io/InformisTry/
 * Singleton Object
 */
public class MyLoggerWithFileOutput {
	
	private static  Logger logger;
	
	public static  Logger getLogger() {
		
		if(logger == null) {
			
			logger = Logger.getLogger("MyLoggerWithFileOutput"); 
			
			// use the method "getLogger(String name)" in Logger class to get a Logger object
			logger = Logger.getLogger("MyLogger"); 
			
			// Declare a FileHandler variable.
			FileHandler fh;
			
			// set the level of the logger as INFO
			logger.setLevel(Level.INFO);
			
			try {
				// create a new FileHandler object with the log file path
				fh = new FileHandler(System.getProperty("user.dir")+"/informistry.log");
				
				// create a SimpleFormatter object to setup the format of log
				SimpleFormatter formatterFH = new SimpleFormatter();  
				// set the SimpleFormatter to the FileHandler
				fh.setFormatter(formatterFH); 
				
				// add the FileHandler to the logger
				logger.addHandler(fh);
			} catch (SecurityException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}  
		}
		 
		 return logger;
	}
}

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * @author Hank Lee
 * Shared in InformisTry -- https://jumperc2p.github.io/InformisTry/
 *
 */
public class Server {
	
	private final int PORT = 61023;
	private Socket connection;
	private static Logger MyLogger = MyLoggerWithFileOutput.getLogger();
	
	public Server() {
		
		 ServerSocket server = null;
		 List<ClientThreadHandler> clients = new ArrayList<>();
		 
		 try{
			 
			// create a new socket
            server = new ServerSocket(PORT);
            MyLogger.log(Level.INFO, "Starts the server");
            System.out.println("Starts the server");

            while (true) {
                MyLogger.log(Level.INFO, "Waiting for new connections...");
                System.out.println("Waiting for new connections...");
                // accept connections from client
                connection = server.accept();
                clients.add(new ClientThreadHandler(connection));
                MyLogger.log(Level.INFO, "Connection accepted");
                MyLogger.log(Level.INFO, "Start the thread.");
                System.out.println("Connection accepted");
                System.out.println("Start the thread.");
                clients.get(clients.size()-1).start();
               
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                server.close();
            } catch (IOException e) { }
        }
	}

	public static void main(String[] args) {
		new Server();
	}

}

import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.NoSuchElementException;
import java.util.Scanner;
import java.util.Timer;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * @author Hank Lee
 * Shared in InformisTry -- https://jumperc2p.github.io/InformisTry/
 *
 */
public class ClientThreadHandler extends Thread {
	
	private Scanner inputFromClient;
    private PrintWriter outputToClient;
    private static Logger MyLogger = MyLoggerWithFileOutput.getLogger();
	
	public ClientThreadHandler(Socket connection) {
		
		// get the OutputStream and InputStream from connection
        try {
			outputToClient = new PrintWriter(connection.getOutputStream(),true);
			inputFromClient = new Scanner(connection.getInputStream());
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	@Override
	public void run() {
		
		  try {
          	
          	while (true) {
          		// send messages to client.
          		outputToClient.println("Send messages to server. Or if you want to end the connection, please enter \"q\":");
          		
          		// create new Timer to schedule TimerTask and start its schedule.
          		Timer timer = new Timer("ServerTaskTimer");
          		// use delay to let the timer start after 3 seconds.
          		long delay = 3000;
          		long period = 3000;
          		timer.scheduleAtFixedRate(new ServerTask(outputToClient), delay, period);
          		// take input from client
          		String clientMessage = inputFromClient.nextLine();
          		// Once it receive the message from client, cancel the timer.
          		timer.cancel();
          		System.out.println("Client says: " + clientMessage);
          		MyLogger.log(Level.INFO, ("Client says: " + clientMessage));
          		// check if the client wants to end the connection.
          		if ("q".equals(clientMessage)) {
          			MyLogger.log(Level.INFO, "Client ends the connection.");
          			break;
          		}
          	}
          }catch (NoSuchElementException ne) {
        	  MyLogger.log(Level.INFO, "Client quits the game.");
          }
	}
}