protected Logger(String name) 
{
    super(name);
}

 public static Logger getLogger(String name) 
{
    return LogManager.getLogger(name);
}

Retrieve a logger named according to the value of the name parameter. If the named logger already exists, then the existing instance will be returned. Otherwise, a new instance is created.

By default, loggers do not have a set level but inherit it from their neareast ancestor with a set level. This is one of the central features of log4j.

 public static Logger getLogger(Class clazz) 
{
    return LogManager.getLogger(clazz.getName());
}

Shorthand for getLogger(clazz.getName()).

 public static Logger getLogger(String name,
    LoggerFactory factory) 
{
    return LogManager.getLogger(name, factory);
}

Like #getLogger(String) except that the type of logger instantiated depends on the type returned by the LoggerFactory#makeNewLoggerInstance method of the factory parameter.

This method is intended to be used by sub-classes.

 public static Logger getRootLogger() 
{
    return LogManager.getRootLogger();
}

Return the root logger for the current logger repository.

The Logger.getName() method for the root logger always returns stirng value: "root". However, calling Logger.getLogger("root") does not retrieve the root logger but a logger just under root named "root".

In other words, calling this method is the only way to retrieve the root logger.

 public boolean isTraceEnabled() 
{
        if (repository.isDisabled(Level.TRACE_INT)) {
            return false;
          }
          return Level.TRACE.isGreaterOrEqual(this.getEffectiveLevel());
}

Check whether this category is enabled for the TRACE Level.

 public  void trace(Object message) 
{
      if (repository.isDisabled(Level.TRACE_INT)) {
        return;
      }
      if (Level.TRACE.isGreaterOrEqual(this.getEffectiveLevel())) {
        forcedLog(FQCN, Level.TRACE, message, null);
      }
}

Log a message object with the TRACE level.

 public  void trace(Object message,
    Throwable t) 
{
      if (repository.isDisabled(Level.TRACE_INT)) {
        return;
      }
      if (Level.TRACE.isGreaterOrEqual(this.getEffectiveLevel())) {
        forcedLog(FQCN, Level.TRACE, message, t);
      }
}

Log a message object with the TRACE level including the stack trace of the Throwable t passed as parameter.

See #debug(Object) form for more detailed information.