log.info("#{} {} is completed.",index,task);

package logbackCfg;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

public class BuildinTester {

    private final static Logger log = LoggerFactory.getLogger(BuildinTester.class);

    public static void main(String[] args) {

        int index=3;

        String task="cleanExpiredData";

        // Traditional way to contruct a log msg

        log.info("#"+index+" "+task+" is completed.");

        // Built-in formatting to contruct a log msg

        log.info("#{} {} is completed.",index,task);

    }

}