| AppenderAttachable | Interface for attaching appenders to objects. | code | html |
| Configurator | Implemented by classes capable of configuring log4j using a URL. | code | html |
| ErrorCode | This interface defines commonly encoutered error codes. | code | html |
| ErrorHandler | Appenders may delegate their error handling to
ErrorHandlers. |
code | html |
| HierarchyEventListener | Listen to events occuring within a Hierarchy . | code | html |
| LoggerFactory | Implement this interface to create new instances of Logger or a sub-class of Logger. | code | html |
| LoggerRepository | A LoggerRepository is used to create and retrieve
Loggers. |
code | html |
| OptionHandler | A string based interface to configure package components. | code | html |
| RendererSupport | code | html | |
| RepositorySelector | The LogManager uses one (and only one)
RepositorySelector implementation to select the
LoggerRepository for a particular application context. |
code | html |
| TriggeringEventEvaluator | Implementions of this interface allow certain appenders to decide when to perform an appender specific action. | code | html |
| Filter | Users should extend this class to implement customized logging event filtering. | code | html |
| DefaultRepositorySelector | code | html | |
| LocationInfo | The internal representation of caller location information. | code | html |
| LoggingEvent | The internal representation of logging events. | code | html |
| NOPLogger | No-operation implementation of Logger used by NOPLoggerRepository. | code | html |
| NOPLoggerRepository | No-operation implementation of LoggerRepository which is used when LogManager.repositorySelector is erroneously nulled during class reloading. | code | html |
| NullWriter | NullWriter is an obsolete class provided only for binary compatibility with earlier versions of log4j and should not be used. | code | html |
| RootCategory | code | html | |
| RootLogger | RootLogger sits at the top of the logger hierachy. | code | html |
| ThrowableInformation | ThrowableInformation is log4j's internal representation of throwables. | code | html |
| VectorWriter | VectorWriter is an obsolete class provided only for binary compatibility with earlier versions of log4j and should not be used. | code | html |