Log4j Logging Levels and Methods

In this tutorial, we will discuss different logging levels and methods. As logging levels and methods are correlated, we will discuss them with some examples.

Logging Levels

The logging levels can be set to the logger. The standard levels are ordered as ALL, TRACE, DEBUG, INFO, WARN, ERROR, FATAL, and OFF. There is a provision to set custom levels by inheriting the org.apache.log4j.Level class. The description of the logging levels is shown in the following table.

Level Description

ALL It is used to log all the events.

TRACE It is used for fine-grained informational events.

DEBUG This level is mainly used at the time of debugging the application.

INFO This level is used to log the informational messages to represent the progress of the application.

WARN It is used to log harmful situations, which are to be avoided.

ERROR This one is used where error events are generated but the error does not terminate the application.

FATAL It designates the error events which cause the abort of the application.

OFF This is the highest level and is used to turn off logging.

There are different ways to set the logging level. One is setting the log level within Java source code and in another approach, the log level can be set using the properties file.

First, we will discuss how to set up the log level in the Java source code. Later we will discuss how to set up the log level using log4j.properties file.

Logging Methods

For the above-mentioned log levels, the associated methods of the Logger class are as follows:

1. public void trace(Object msg)

2. public void debug(Object msg)

3. public void info(Object msg)

4. public void warn(Object msg)

5. public void error(Object msg)

6. public void fatal(Object msg)

Happy Exploring!