1. Create and Use a Custom Logger
This program demonstrates how to create a custom logger using the Logger class. The custom logger records information, warning, and error messages.
import java.util.logging.Logger;
public class CustomLoggerExample {
private static final Logger logger =
Logger.getLogger("MyCustomLogger");
public static void main(String[] args) {
logger.info("Application Started");
logger.warning("Low Memory Warning");
logger.severe("Application Error");
System.out.println("Custom Logger Executed Successfully.");
}
}Output:
Aug 07, 2026 11:04:45 AM CustomLoggerExample main
INFO: Application Started
Aug 07, 2026 11:04:45 AM CustomLoggerExample main
WARNING: Low Memory Warning
Aug 07, 2026 11:04:45 AM CustomLoggerExample main
SEVERE: Application Error
Custom Logger Executed Successfully.Code language: CSS (css)2. Custom Logger with ConsoleHandler
This program creates a custom logger and attaches a ConsoleHandler. The handler displays formatted log messages on the console.
import java.util.logging.ConsoleHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;
public class CustomConsoleLogger {
private static final Logger logger =
Logger.getLogger("ConsoleLogger");
public static void main(String[] args) {
ConsoleHandler handler = new ConsoleHandler();
handler.setFormatter(new SimpleFormatter());
handler.setLevel(Level.ALL);
logger.addHandler(handler);
logger.setUseParentHandlers(false);
logger.setLevel(Level.ALL);
logger.info("Program Started");
logger.warning("Invalid Input");
logger.severe("System Failure");
}
}Output:
Aug 07, 2026 11:06:18 AM CustomConsoleLogger main
INFO: Program Started
Aug 07, 2026 11:06:18 AM CustomConsoleLogger main
WARNING: Invalid Input
Aug 07, 2026 11:06:18 AM CustomConsoleLogger main
SEVERE: System FailureCode language: CSS (css)3. Custom Logger with FileHandler
This program creates a custom logger that writes log messages into a file. The log records are formatted using SimpleFormatter.
import java.util.logging.FileHandler;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;
public class CustomFileLogger {
private static final Logger logger =
Logger.getLogger("FileLogger");
public static void main(String[] args) {
try {
FileHandler handler =
new FileHandler("customlogger.log");
handler.setFormatter(new SimpleFormatter());
logger.addHandler(handler);
logger.setUseParentHandlers(false);
logger.info("Application Started");
logger.warning("Database Connection Slow");
logger.severe("Unexpected Exception");
System.out.println("Logs stored in customlogger.log");
} catch (Exception e) {
System.out.println(e);
}
}
}Output:
Logs stored in customlogger.log
Content of customlogger.log:
Aug 07, 2026 4:39:04 AM CustomFileLogger main
INFO: Application Started
Aug 07, 2026 4:39:04 AM CustomFileLogger main
WARNING: Database Connection Slow
Aug 07, 2026 4:39:04 AM CustomFileLogger main
SEVERE: Unexpected Exception
Code language: CSS (css)