Android Log Levels

Question

Android supports various log levels, Verbose, Debug, Info, Warn and Error. I understand how the logging levels work; I'm more interested in the typical output expected for a given level.

For example, when developing an application I might be curious when a certain method is doing something (this often tends to be for debugging purposes). I'll look through the logs to make sure the methods are being called in an expected order, if the network response is what I think it should be, if the parsers finds the right information, etc.

Why would some one use Verbose vs Debug vs Info?

From the perspective of a developer, for a first, second, or third party application aren't all logs for debugging purposes? (assuming devs don't stare a logs for fun... I'm not that sadistic)

From the perspective of a consumer, when the s*** hits the fan and they need to contact customer support because their super important / business critical application isn't working a developer uses the log for debugging purposes.

The only reason I could see for using verbose or info is perhaps metrics gathering / data warehouse related operations. If so, why use verbose vs info.

Not sure If I'm overcomplicating this or if the android framework is...

Answer 1

I basically follow what Tomasz Nurkiewicz has to say when considering logging level:

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ERROR – something terribly wrong had happened, that must be investigated immediately. No system can tolerate items logged on this level. Example: NPE, database unavailable, mission critical use case cannot be continued.

WARN – the process might be continued, but take extra caution. Example: “Application running in development mode” or “Administration console is not secured with a password”. The application can tolerate warning messages, but they should always be justified and examined.

INFO – Important business process has finished. In ideal world, administrator or advanced user should be able to understand INFO messages and quickly find out what the application is doing. For example if an application is all about booking airplane tickets, there should be only one INFO statement per each ticket saying “[Who] booked ticket from [Where] to [Where]“. Other definition of INFO message: each action that changes the state of the application significantly (database update, external system request).

DEBUG – Developers stuff.

VERBOSE – Very detailed information, intended only for development. You might keep trace messages for a short period of time after deployment on production environment, but treat these log statements as temporary, that should or might be turned-off eventually. The distinction between DEBUG and VERBOSE is the most difficult, but if you put logging statement and remove it after the feature has been developed and tested, it should probably be on VERBOSE level.

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My most favorite level is WTF(2.2+) which is supposed to stand for "What a Terrible Failure", for situations that should never happen.

I normally use "info" for simple messages.