There are many legitimate reasons to create log files on a mobile device, such as keeping track of crashes, errors, and usage statistics. Log files can be stored locally when the app is offline and sent to the endpoint once the app is online. However, logging sensitive data may expose the data to attackers or malicious applications, and it violates user confidentiality. You can create log files in several ways.
The Log.wtf() method is used to log terrible failures that should never happen. ("WTF" stands for "What a Terrible Failure!" of course.)