Java by API/java.util.logging/Handler

Handler: setFormatter(Formatter newFormatter)

 
import java.io.IOException;
import java.util.logging.ConsoleHandler;
import java.util.logging.FileHandler;
import java.util.logging.Handler;
import java.util.logging.Logger;
import java.util.logging.XMLFormatter;
public class MainClass {
  public static void main(String args[]) {
    Logger logger = Logger.getLogger("my.log");
    Handler handler = null;
    try {
      handler = new FileHandler("messages.log");
    } catch (IOException e) {
      System.out.println("Could not create file. Using the console handler");
      handler = new ConsoleHandler();
    }
    logger.addHandler(handler);
    handler.setFormatter(new XMLFormatter());
    logger.info("Our first logging message");
    logger.severe("Something terrible happened");
  }
}

implements Handler

  

import java.util.ArrayList;
import java.util.List;
import java.util.logging.Handler;
import java.util.logging.LogRecord;
import java.util.logging.Logger;
public class Main {
  private static Logger logger = Logger.getLogger("CustomHandler");
  private static List<String> strHolder = new ArrayList<String>();
  public static void main(String[] args) {
    logger.addHandler(new Handler() {
      public void publish(LogRecord logRecord) {
        strHolder.add(logRecord.getLevel() + ":");
        strHolder.add(logRecord.getSourceClassName() + ":");
        strHolder.add(logRecord.getSourceMethodName() + ":");
        strHolder.add("<" + logRecord.getMessage() + ">");
        strHolder.add("\n");
      }
      public void flush() {
      }
      public void close() {
      }
    });
    logger.warning("Logging Warning");
    logger.info("Logging Info");
    System.out.print(strHolder);
  }
}