// Project: Patterns1
// Module: logger
// Source code file: Logger.java.
// Illustrate the Singleton software pattern.
// Only one instance of a singleton class is allowed.
// This is accomplished by using a private constructor.
// Create the file c:/logger before running this example.

import java.io.*;
import java.text.*;
import java.util.Date;
public class Logger {
    private final static String LOG_FILE_NAME =
            "c:/logger/logfile.txt";
    private static int loggerCount;
    private PrintWriter fileHandle = null;
    private static Logger loggerInstance;

    private Logger( ) {
        try {
            fileHandle = new PrintWriter(
                new BufferedWriter(
                    new FileWriter(LOG_FILE_NAME, true)));
        }
        catch (IOException e) {
            fileHandle = null;
        }
    }

    public static Logger getInstance( ) {
        if (loggerCount == 0) {
            loggerInstance = new Logger( );
            loggerCount++;
        }
        return loggerInstance;
    }

    public void writeLogEntry(String name, String entry) {
        DateFormat dateFormat =
                new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
        Date date = new Date();
        String timeStamp = dateFormat.format(date);
        String NEW_LINE = System.getProperty("line.separator");
        fileHandle.println("Name: " + name + NEW_LINE +
                "Time Stamp:" + timeStamp + NEW_LINE +
                "Entry: " + entry + NEW_LINE);
        fileHandle.flush( );
    }
}