In reviewJNR-006-L04

Logging exceptions well

On This Lesson 4 topics

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In this lesson

log an exception once, with its stack trace.

Pass the exception as the last argument: log.error("Payment failed for {}", id, e).
Do not use e.getMessage() alone; you lose the stack trace.
Log it once, at the place that handles it.
Do not log and rethrow: the same error then appears many times.
Either handle it (log) or pass it up (throw), not both.

Draft outline details

java

try { pay(order); }
catch (PaymentException e) {
    log.error("Payment failed for order {}", order.id(), e);
}

Why is log-and-rethrow bad?

Show answer

The same error is logged several times and confuses readers.

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