This API provides a flexible and consistent logging mechanism. The logging level determins the volumn of log messages. In other words, only log records with a level equal to or higher than the set logging level will be actually generated. At global initialization time, read the global logging configuration file if any and initialize Logger's global configuration, including the global logging level, the logging output devices and flags et al.
Step 2. In each class, define an static instance of the Logger. Each instance will inherit the global settings initially, but you may override them at any time. Each Logger instance has a name, which follows Java's package naming convention. You can re-config all the Logger instances in a particular namespace dynamically during run-time. Step 3. In your methods log messages as you see fit, using one of the Logger's logging methods. For instance use Logger's fatal Method to log a fatal message, and info method to log an informational message.
Logs errors detected in the program. Usually recoverable. Set this flag if log records should include the name of the logging thread. The default setting is on so that no thread name will appear in any log record.
Sets the global logging level. This level will be inherited by each Logger instance. All existing loggers will be affected and use this new logging level. Sets the global logging level for the named loggers.
The advantage of the non-static form is that you can declare it in an abstract base class like follows without worrying that the right classname will be used:. However its disadvantage is obviously that a whole new logger instance will be created for every instance of the class.
This may not per se be expensive, but it adds a significant overhead. If you'd like to avoid this, you'd like to use the static form instead.
But its disadvantage is in turn that you have to declare it in every individual class and take care in every class that the right classname is been used during logger's construction because getClass cannot be used in static context. However, in the average IDE you can create an autocomplete template for this. On the other hand, if you obtain the logger by a factory which in turn may cache the already-instantiated loggers, then using the non-static form won't add that much overhead.
Log4j for example has a LogManager for this purpose. I used to think that all loggers should be static; however, this article at wiki. Declaring a logger as static prevents the declaring class and associated classloaders from being garbage collected in J2EE containers that use a shared classloader. This will result in PermGen errors if you redeploy your application enough times. Static key word in java is made for the same. Hence we declare it static. How are we doing?
Please help us improve Stack Overflow. Take our short survey. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Why do we declare Loggers static final? Ask Question. Asked 10 years, 4 months ago. Active 7 months ago. Viewed k times. In Java, why is it best practice to declare a logger static final? Improve this question. Add a comment. Active Oldest Votes. Improve this answer.
Community Bot 1 1 1 silver badge. Tomasz Nurkiewicz Tomasz Nurkiewicz k 67 67 gold badges silver badges bronze badges. Some follow Java naming convention religiously nothing wrong with that , but I prefer easier to write and more pleasant to read log name rather than scattering the code with LOG.
Just a matter of dev. Please note that it is no longer always recommended to declare loggers as static and final, see slf4j. Logger isn't constant. Show 8 more comments. This is how you use slf4j with jcabi-log : import com. An interesting alternative and definitely cleaner. I wonder how this scales compared to individual class loggers. Write longer Logger.. The first comment in the related blog post indicates the evil side of the static methods : So using private final Logger is the best practice I guess.
Andrzej Doyle Andrzej Doyle When would you want to change the value of the field? Jon Skeet Jon Skeet 1. In many-many cases it IS obvious without adding the word final, which it this case becomes a kind of junk. Dima: Well I'm still grateful that the compiler will still throw an error if I do accidentally try to change the value in these cases
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