Setting java.util.logging.config.file at runtime

I am trying to set the java util logging config file at runtime to avoid having to set it as a VM parameter. But this just doesn't work. Whenever I am trying to reread the configuration, logging is disabled at all.

See the following code snippet:

package test;

import java.io.FileInputStream;
import java.util.logging.Level;
import java.util.logging.LogManager;
import java.util.logging.Logger;

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

  public static void main(String[] args) throws Exception {
    System.out.println("--- start");
    LOGGER.log(Level.SEVERE, "SEVERE 1");
    LOGGER.log(Level.FINEST, "FINEST 1");
    LogManager.getLogManager().readConfiguration();
    LOGGER.log(Level.SEVERE, "SEVERE 2");
    LOGGER.log(Level.FINEST, "FINEST 2");
    LogManager.getLogManager().readConfiguration(new FileInputStream("/tmp/logging.properties"));
    LOGGER.log(Level.SEVERE, "SEVERE 3");
    LOGGER.log(Level.FINEST, "FINEST 3");
    System.out.println("--- end");
  }
}

This is the output if I run the class without any VM argument:

--- start
09.11.2012 09:59:25 test.A main
SCHWERWIEGEND: SEVERE 1
09.11.2012 09:59:25 test.A main
SCHWERWIEGEND: SEVERE 2
--- end

As you can see, only the SEVERE levels are logged, as this is the default of the JREs logging.properties. Calling LogManager#readConfiguration() doesn't change anything. But when trying to read the configuration from my logging.properties, absolutely nothing is logged. There is no difference in calling LogManager#readConfiguration(InputStream) or setting the java.util.logging.config.file property and calling LogManager#readConfiguration().

Now see the next output, when I run the same code with the VM property -Djava.util.logging.config.file=/tmp/logging.properties :

--- start
2012-11-09 10:03:44.0838 SEVERE  [test.A#main()] - SEVERE 1
2012-11-09 10:03:44.0843 FINEST  [test.A#main()] - FINEST 1
--- end

As you can see, both the SEVERE and the FINEST levels are logged and they are logged in a different format. Both is specified in my custom logging.properties. But logging stops here after calling LogManager#readConfiguration()! This is different from the example above and I don't understand it. Also, just as in the example above, calling LogManager#readConfiguration(InputStream) doesn't work.

So what is the problem? According to the javadoc setting the java.util.logging.config.file property at runtime should work. Also both readConfiguration() methods should work as I expect. So what is the problem?

Solution

Probably a problem with your logging properties. I noticed that I had to use both level specifications in the config (root and console) to get the result.
Maybe your root logger level is below FINEST, e.g. INFO (.level=INFO).
Or not set at all, in which case I suppose it to be INFO.

I ran your code with the following logging.properties:

handlers=java.util.logging.ConsoleHandler
.level=FINEST
java.util.logging.ConsoleHandler.level=FINEST

Without specifying the -Djava.util.logging.config.file=/tmp/logging.properties output was:

--- start
09.11.2012 14:25:49 testing.Scribble main
SCHWERWIEGEND: SEVERE 1
09.11.2012 14:25:49 testing.Scribble main
SCHWERWIEGEND: SEVERE 2
09.11.2012 14:25:49 testing.Scribble main
SCHWERWIEGEND: SEVERE 3
09.11.2012 14:25:49 testing.Scribble main
AM FEINSTEN: FINEST 3
--- end

Looks correct! (My test class is called testing.Scribble, thats the only difference)

Using -Djava.util.logging.config.file=/tmp/logging.properties output is:

--- start
09.11.2012 14:31:06 testing.Scribble main
SCHWERWIEGEND: SEVERE 1
09.11.2012 14:31:06 testing.Scribble main
AM FEINSTEN: FINEST 1
09.11.2012 14:31:06 testing.Scribble main
SCHWERWIEGEND: SEVERE 2
09.11.2012 14:31:06 testing.Scribble main
AM FEINSTEN: FINEST 2
09.11.2012 14:31:06 testing.Scribble main
SCHWERWIEGEND: SEVERE 3
09.11.2012 14:31:06 testing.Scribble main
AM FEINSTEN: FINEST 3
--- end

Looks also correct!