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How to obtain or create a Logger?

Since JDK 1.4 a logging API was introduced into the Java class libraries. This API enable our application to logs some messages to record our application activities.

To create an instance of Logger we can call the Logger.getLogger() factory method which will return the available logger for the given namespace or it will create a new one when it doesn't exist.

package com.javacoderanch.example.util.logging;

import java.util.logging.Logger;

public class LoggingDemo {
    public static void main(String[] args) {
        //
        // Obtaining an instance of Logger. This will create a new Logger
        // is it doesn't exist.
        //
        Logger log = Logger.getLogger(LoggingDemo.class.getName());

        //
        // Log some message using a different type of severity leve.
        //
        log.info("Info Message");
        log.warning("Warning Message");
        log.severe("Severe Message");
        log.config("Config Message");
        log.fine("Fine Message");
        log.finer("Finer Message");
        log.finest("Finest Message");
    }
}

After we create the Logger instance we can create a message log by calling the logging method such as info(String message), warning(String message) and severe(String message). Below are some message produces by the Logger.

27 Apr 09 13:01:07 com.javacoderanch.example.util.logging.LoggingDemo main
INFO: Info Message
27 Apr 09 13:01:07 com.javacoderanch.example.util.logging.LoggingDemo main
WARNING: Warning Message
27 Apr 09 13:01:07 com.javacoderanch.example.util.logging.LoggingDemo main
SEVERE: Severe Message