How to display stack trace on a caught exception?

Your logging framework should have the ability to log exceptions, so simply passing the exception to the proper .error(Object, Throwable) call should be enough:

• log4j can do it
• commons logging can do it
• java.util.logging can do it

If your logging framework can't do that, or you need the stack trace in a String for any other reason, then it becomes a bit harder. You'll have to create a PrintWriter wrapping a StringWriter and call .printStackTrace() on the Exception:

StringWriter sw = new StringWriter();
ex.printStackTrace(new PrintWriter(sw));
String stacktrace = sw.toString();

Throwable.getStackTrace returns an array of StackTraceElements, hence the toString method is returning a textual representation of the array itself.

In order to actually retrieve the stack trace information, one would have to go through each StackTraceElement to get more information.

Have you tried?

private void _showErrorMessage(Exception e) {
    log.error("Hey! got an exception", e);
}

I use the ExceptionUtils#getFullStackTrace method of Jakarta Commons Lang