java.util.logging: how to suppress date line

From Java SE 7 there is a new system property: java.util.logging.SimpleFormatter.format.

The same property is also configurable on the java.util.logging properties file (logging.properties). If you are an Eclipse user, and you are annoyed by the double line message in the console output, you could change the jre logging.properties file (JDK_HOME/jre/lib/logging.properties) in this way:

java.util.logging.SimpleFormatter.format=%4$s: %5$s [%1$tc]%n

Some example format is available here: http://docs.oracle.com/javase/7/docs/api/index.html?java/util/logging/SimpleFormatter.html.

The problem is caused by a handler in the parent log. The solution is to remove all handlers from the parent log, and then add own custom handler. This code removes handlers from the parent log:

      for(Handler iHandler:log.getParent().getHandlers())
        {
        log.getParent().removeHandler(iHandler);
        }

Write a custom formatter extending java.util.logging.Formatter class and implement the String format(LogRecord) method according to your needs. For example, the following formatter shows only the log message (and the throwable stacktrace if an exception is being logged):

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.logging.Formatter;
import java.util.logging.LogRecord;

class CustomRecordFormatter extends Formatter {
    @Override
    public String format(final LogRecord r) {
        StringBuilder sb = new StringBuilder();
        sb.append(formatMessage(r)).append(System.getProperty("line.separator"));
        if (null != r.getThrown()) {
            sb.append("Throwable occurred: "); //$NON-NLS-1$
            Throwable t = r.getThrown();
            PrintWriter pw = null;
            try {
                StringWriter sw = new StringWriter();
                pw = new PrintWriter(sw);
                t.printStackTrace(pw);
                sb.append(sw.toString());
            } finally {
                if (pw != null) {
                    try {
                        pw.close();
                    } catch (Exception e) {
                        // ignore
                    }
                }
            }
        }
        return sb.toString();
    }
}

This is how you use it:

import java.util.logging.ConsoleHandler;
import java.util.logging.Logger;

class A {
    private static final Logger LOGGER = Logger.getLogger(A.class.getName());

    static {
        CustomRecordFormatter formatter = new CustomRecordFormatter();
        ConsoleHandler consoleHandler = new ConsoleHandler();
        consoleHandler.setFormatter(formatter);
        LOGGER.addHandler(consoleHandler);
    }

    public void doSomething() {
        LOGGER.info("something happened");
    }
}