log4j-logging

log4j is a very popular logging library for Java development. It provides convenient and flexible logging mechanism as well as fast performance.

Typically, configuring log4j involves in the following tasks:

• Configure the root logger.
• Configure individual loggers (if needed).
• Specify appenders.
• Specify message layout.

The specifiers used in the above example:

• t: name of the current executing thread.
• p: priority
• c: category
• m: log message.
• n: line separator character.

There are three ways to configure log4j:

• Using .properties file.
• Using XML file.
• Using Java code programmatically.