Question

I am adding a logger to my program, surfing the net I add to my code a very simple logger with the basic 2-line definition:

private static final Logger LOG = Logger.getLogger(GUI.class.getName());

public MyClass(){

    //other stuff...
    LOG.info("text to log");
    //other stuff...
}

After few hours of developing I was wondering how to format the style of the logged text and I came to this class:

java.util.logging.SimpleFormatter

Reading the Javadoc I can find:

The formatting can be customized by specifying the format string in the java.util.logging.SimpleFormatter.format property.

There are also few examples:

Some example formats:
java.util.logging.SimpleFormatter.format="%4$s: %5$s [%1$tc]%n"
This prints 1 line with the log level (4$), the log message (5$) and the timestamp (1$) in a square bracket.

WARNING: warning message [Tue Mar 22 13:11:31 PDT 2011]

I tried each one of them, but the “format” field is “not visible” (private I suppose) so I can’t edit it directly. There isn’t any method similar to
setStringVar(String regex);
to set the var from the outside.

I tried to extends the class
public class MyClass extends SimpleFormatter{

but “format” var is not editable. I also tried extending Formatter (the super-class of SimpleFormatter) without success.

The only thing I could do is to extend SimpleFormatter and manually override its:
public String format(LogRecord rec);
with boring and complicated code.

I was just wondering if is there any way to simply use the inside regex reader of the SimpleFormatter Class

EDIT:errors

Answer 1

Have you looked at the JavaDoc. It gives a overview of the SimpleFormatter.

Also, format is a public method within SimpleFormatter.

Further the line

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

should be defined in a properties file and not the Java class.

To be honest, I don’t use java.util.logging I use log4j as Fildor mentioned. I find it much simpler. First you need a config file, like log4j.xml below:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd" >
<log4j:configuration>
    <appender name="stdout" class="org.apache.log4j.ConsoleAppender">
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d %5p %c{1}:%L - %m%n"/>
        </layout>
    </appender>
    <root>
        <priority value="debug"></priority>
        <appender-ref ref="stdout"/>
    </root>
</log4j:configuration>

You are free to tweak the conversion pattern, see PatternLayout for details. Then in your class define the following private static member

static org.apache.log4j.Logger LOG = org.apache.log4j.Logger.getLogger(Testing.class);

The simply when you want to output logging do:

LOG.error("Test Error");