Java : SimpleFormatter (logging) with Examples
December 31, 2023 
March 19, 2022
SimpleFormatter (Java SE 17 & JDK 17) API Examples.
You will find code examples on most SimpleFormatter methods.
Summary
Print a brief summary of the LogRecord in a human readable format. The summary will typically be 1 or 2 lines.
final var logger = Logger.getLogger("com.example.logging");
logger.setUseParentHandlers(false);
// The ConsoleHandler has the SimpleFormatter by default.
final var handler = new ConsoleHandler();
System.out.println(handler.getFormatter()); // java.util.logging.SimpleFormatter@d76b01a
logger.addHandler(handler);
logger.info("TEST LOG : 1");
logger.info("TEST LOG : 2");
logger.info("TEST LOG : 3");
// Result
// ↓
//Mar 18, 2022 12:07:30 AM com.example.logging.SimpleFormatterTest$1 method
//INFO: TEST LOG : 1
//Mar 18, 2022 12:07:30 AM com.example.logging.SimpleFormatterTest$1 method
//INFO: TEST LOG : 2
//Mar 18, 2022 12:07:30 AM com.example.logging.SimpleFormatterTest$1 method
//INFO: TEST LOG : 3
Constructors
SimpleFormatter ()
Create a SimpleFormatter.
final var logger = Logger.getLogger("com.example.logging");
logger.setUseParentHandlers(false);
final var pattern = Path.of("R:", "java-work", "log.txt");
final var handler = new FileHandler(pattern.toString());
logger.addHandler(handler);
System.out.println(handler.getFormatter()); // java.util.logging.XMLFormatter@2c83f1d1
handler.setFormatter(new SimpleFormatter());
System.out.println(handler.getFormatter()); // java.util.logging.SimpleFormatter@79acc4ff
logger.info("TEST LOG!");
System.out.print(Files.readString(pattern));
// Result
// ↓
//Mar 18, 2022 12:08:02 AM com.example.logging.SimpleFormatterTest$2 method
//INFO: TEST LOG!
Methods
String format (LogRecord record)
Format the given LogRecord.
class MyFormatter extends SimpleFormatter {
@Override
public String format(LogRecord logRecord) {
logRecord.setMessage(logRecord.getMessage() + " : override format!");
return super.format(logRecord);
}
}
final var logger = Logger.getLogger("com.example.logging");
logger.setUseParentHandlers(false);
final var handler = new ConsoleHandler();
logger.addHandler(handler);
handler.setFormatter(new MyFormatter());
logger.info("TEST LOG!");
// Result
// ↓
//Mar 18, 2022 12:08:44 AM com.example.logging.SimpleFormatterTest$3 method
//INFO: TEST LOG! : override format!