Java Quick Tip: Parameterized Logging

I hate writing ugly, concatenated logging statements like this:

package com.arc90.example;
import java.util.logging.Logger;
public class LoggingExample1
{
public static void main(String[] args)
{
Logger logger = Logger.getLogger(LoggingExample1.class.getName());
String user = "dougb";
int logins = 17;
int purchases = 2;
logger.info("User " + user + " has logged in " + logins +
" times and made " + purchases + " purchases.");
}
}

Fortunately, the Java Logging API gives you the ability to parameterize your statements (similar to JDBC prepared statements) so that you can turn the above into something like this:

package com.arc90.example;
import java.util.logging.Level;
import java.util.logging.Logger;
public class LoggingExample2
{
public static void main(String[] args)
{
Logger logger = Logger.getLogger(LoggingExample2.class.getName());
String user = "dougb";
int logins = 17;
int purchases = 2;
// Single parameter
logger.log(Level.INFO, "User {0} successfully logged in.", user);
// Multiple parameters
logger.log(Level.INFO, "User {0} has logged in {1} times and made {2} purchases.",
new Object[] {user, logins, purchases});
}
}

You’ll need to use the logger.log(…) method rather than the more convenient logger.fine(…), logger.info(…) (etc.) methods, but in the end it makes for much cleaner code.