Creating custom log levels in Java Logging API

20 Sep 2023

logging

Logging is an essential component of any software application as it helps in tracking and analyzing the application’s behavior and performance. The Java Logging API provides a flexible and powerful way to incorporate logging in your Java applications.

By default, the Java Logging API provides several predefined log levels such as SEVERE, WARNING, INFO, and FINE. However, there may be cases where you need to define your own custom log levels to track specific events or conditions in your application.

Why Create Custom Log Levels?

Creating custom log levels allows you to categorize and prioritize log messages based on your application’s specific requirements. By defining custom log levels, you can log messages at different granularities, making it easier to filter and analyze logs.

Implementing Custom Log Levels

To create custom log levels in the Java Logging API, follow these steps:

Define your custom log levels: You can define your custom log levels by extending the java.util.logging.Level class or by using the java.util.logging.Level constructor with a unique integer value. For example:

 public class MyCustomLevel extends Level {
     private static final int MY_CUSTOM_LEVEL_VALUE = 1001;

     public static final Level MY_CUSTOM_LEVEL = new MyCustomLevel();

     private MyCustomLevel() {
         super("MY_CUSTOM_LEVEL", MY_CUSTOM_LEVEL_VALUE);
     }
 }

Configure the logging properties: In order for the custom log levels to be recognized and utilized, you need to configure the logging properties file (usually logging.properties) to map your custom level name to the corresponding class. For example:
```
 .level=FINE
 .handlers=java.util.logging.ConsoleHandler

 com.example.MyCustomLevel=FINER
```

Use custom log levels in your application: Once the custom log level is defined and configured, you can use it in your application’s code by creating a logger and logging messages with the custom log level. For example:

 import java.util.logging.Logger;

 public class MyApp {
     private static final Logger LOGGER = Logger.getLogger(MyApp.class.getName());

     public void doSomething() {
         LOGGER.log(MyCustomLevel.MY_CUSTOM_LEVEL, "Custom log message");
     }
 }

Now, when running your application, the messages logged with the custom log level will be captured according to the configured logging properties.

Conclusion

Creating custom log levels in the Java Logging API gives you the flexibility to log messages at different granularities, allowing for better analysis and troubleshooting of your application. By following the steps outlined above, you can define and utilize custom log levels in your Java applications effectively.

#java #logging