Why are we checking if debugging or logerror is enabled?

Question

I always see it is better to check whether log.isDebugEnabled before adding a log.debug statement.

I guess it should be taken care by the logging framework, could you please let me know what is the advantage of having this condition check?

Answer 1

Consider the following example:

if (log.isDebugEnabled()) {
    log.debug("This is my complicated object" + veryComplicatedObject.toString());
}

String concatenation may be expensive (memory-wise), and there is no reason to perform it if we aren't going to log it anyway. Checking the logging level beforehand saves constructing redundant strings.