Question

Hi I am trying to implement the java logging in my application. I want to use two handlers.
A file handler and my own console handler. Both of my handlers work fine. My logging is send to a file and to the console .
My logging is also sent to the default console handler, which i do not want. If you run my code you will see extra two line sent to the console. I don’t want to use the default console handler. Does anyone know how to disable the default console handler.
I only want to use the two handlers I have created.

Handler fh = new FileHandler("test.txt");
fh.setFormatter(formatter);
logger.addHandler(fh);

---

Handler ch = new ConsoleHandler();
ch.setFormatter(formatter);
logger.addHandler(ch);

---

import java.util.Date;
import java.util.logging.ConsoleHandler;
import java.util.logging.FileHandler;
import java.util.logging.Formatter;
import java.util.logging.Handler;
import java.util.logging.Level;
import java.util.logging.LogManager;
import java.util.logging.LogRecord;
import java.util.logging.Logger;

public class LoggingExample {
    private static Logger logger = Logger.getLogger("test");

    static {
        try {
            logger.setLevel(Level.INFO);

            Formatter formatter = new Formatter() {

                @Override
                public String format(LogRecord arg0) {
                    StringBuilder b = new StringBuilder();
                    b.append(new Date());
                    b.append(" ");
                    b.append(arg0.getSourceClassName());
                    b.append(" ");
                    b.append(arg0.getSourceMethodName());
                    b.append(" ");
                    b.append(arg0.getLevel());
                    b.append(" ");
                    b.append(arg0.getMessage());
                    b.append(System.getProperty("line.separator"));
                    return b.toString();
                }

            };

            Handler fh = new FileHandler("test.txt");
            fh.setFormatter(formatter);
            logger.addHandler(fh);

            Handler ch = new ConsoleHandler();
            ch.setFormatter(formatter);
            logger.addHandler(ch);

            LogManager lm = LogManager.getLogManager();
            lm.addLogger(logger);
        } catch (Throwable e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        logger.info("why does my test application use the standard console logger ?\n" + " I want only my console handler (Handler ch)\n " + "how can i turn the standard logger to the console off. ??");
    }
}

Answer 1

The default console handler is attached to the root logger, which is a parent of all other loggers including yours. So I see two ways to solve your problem:

If this is only affects this particular class of yours, the simplest solution would be to disable passing the logs up to the parent logger:

logger.setUseParentHandlers(false);

If you want to change this behaviour for your whole app, you could remove the default console handler from the root logger altogether before adding your own handlers:

Logger globalLogger = Logger.getLogger("global");
Handler[] handlers = globalLogger.getHandlers();
for(Handler handler : handlers) {
    globalLogger.removeHandler(handler);
}

Note: if you want to use the same log handlers in other classes too, the best way is to move the log configuration into a config file in the long run.