How to send a stacktrace to log4j?

java

logging

exception-handling

stacktrace

byAnton Shumikhin·Feb 21, 2025

You can tackle stacktraces logging in log4j using the logger.error(String message, Throwable t) method. This logs your custom messages and full stacktrace straight from the exception.

private static final Logger LOGGER = Logger.getLogger(YourClass.class);

try {
  // This is where the magic happens... or breaks
} catch (Exception e) {
  LOGGER.error("Exception: Houston, we have a problem here", e);
}

Don't forget to set your logger to ERROR level, ensuring you capture the full glory of that stacktrace, as well as Indie band names!

Advanced logging methods you wish you knew earlier

Seems like you're not much into "magic" logging? Let's dive a bit deeper into customization capabilities.

Add more context to catch block

Become the Sherlock Holmes of logging. Augment your catch blocks with timestamps and thread ids for that extra debugging clue.

catch (Exception e) {
  LOGGER.error("{} failed and caused a scene at {} in the realm of thread {}", new Object[]{"Operation", new Date(), Thread.currentThread().getName()}, e);
  // Timestamp and thread id added. It's like the breadcrumbs of coding!
}

When strings are your thing: ExceptionUtils

Apache Commons Lang to the rescue when you want a stacktrace sings to you in a string:

import org.apache.commons.lang3.exception.ExceptionUtils;

catch (Exception e) {
  String stacktrace = ExceptionUtils.getStackTrace(e);
  LOGGER.error(stacktrace); // Your stacktrace, serenaded in a string
}

Be it for storing stacktrace in a database, sending it to your pet parrot, or custom formatting - this is a handy utility to save the day.

Retrieve a stacktrace from thin air

Life would be sweet if exceptions always showed up when things went wrong! For a diagnostic without throwing an exception, grab a stacktrace like this:

String trace = Arrays.stream(Thread.currentThread().getStackTrace())
                     .map(StackTraceElement::toString)
                     .collect(Collectors.joining(System.lineSeparator()));
LOGGER.error("Diagnostic stack trace:", trace);
// Just like fishing, but instead of fish, you catch stack traces. Fun, right?

It's highly beneficial to diagnose curious behaviour manifested out of the blue!

Do not shy away from using different logging levels

Why not try with warnings or debug messages for less severe issues?

LOGGER.warn("Rough day, not a fatal failure though:", e);

Or ensure reading comfort by customizing Log4j layouts. Let newlines take shape for your stacktrace elements! Be mindful and use them properly to maximise readability.

Leverage open source stacktrace utilities

Bring the best out of tools like Apache Commons Lang's ExceptionUtils or others to filter out the redundant, so the important stands out. Make sure such libraries are readily available as Maven artifacts or Git sources.

Stay vigilant of Unicode quirks

Sometimes, the Unicode parsing is the villain in disguise. Go the extra step to integrate a Unicode converter, maintain proper output and keep your logs tidy.