org.slf4j

Interface Logger

  • All Known Subinterfaces:
    LocationAwareLogger
    All Known Implementing Classes:
    EventRecodingLogger, MarkerIgnoringBase, NOPLogger, SubstituteLogger 

    public interface Logger
    The org.slf4j.Logger interface is the main user entry point of SLF4J API. It is expected that logging takes place through concrete implementations of this interface.

    Typical usage pattern:

     import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 public class Wombat {

   final static Logger logger = LoggerFactory.getLogger(Wombat.class);
   Integer t;
   Integer oldT;

   public void setTemperature(Integer temperature) {
     oldT = t;
     t = temperature;
     logger.debug("Temperature set to {}. Old temperature was {}.", t, oldT);
     if(temperature.intValue() > 50) {
       logger.info("Temperature has risen above 50 degrees.");
     }
   }
 }
    Be sure to read the FAQ entry relating to parameterized logging. Note that logging statements can be parameterized in presence of an exception/throwable.

    Once you are comfortable using loggers, i.e. instances of this interface, consider using MDC as well as Markers.

    • Field Detail

      • ROOT_LOGGER_NAME

        static final String ROOT_LOGGER_NAME
        Case insensitive String constant used to retrieve the name of the root logger.
        Since:
        1.3
        See Also:
        Constant Field Values

    • Method Detail

      • getName

        String getName()
        Return the name of this Logger instance.
        Returns:
        name of this logger instance

      • isTraceEnabled

        boolean isTraceEnabled()
        Is the logger instance enabled for the TRACE level?
        Returns:
        True if this Logger is enabled for the TRACE level, false otherwise.
        Since:
        1.4

      • trace

        void trace(String msg)
        Log a message at the TRACE level.
        Parameters:
        msg - the message string to be logged
        Since:
        1.4

      • trace

        void trace(String format,
           Object arg)
        Log a message at the TRACE level according to the specified format and argument.

        This form avoids superfluous object creation when the logger is disabled for the TRACE level.

        Parameters:
        format - the format string
        arg - the argument
        Since:
        1.4

      • trace

        void trace(String format,
           Object arg1,
           Object arg2)
        Log a message at the TRACE level according to the specified format and arguments.

        This form avoids superfluous object creation when the logger is disabled for the TRACE level.

        Parameters:
        format - the format string
        arg1 - the first argument
        arg2 - the second argument
        Since:
        1.4

      • trace

        void trace(String format,
           Object... arguments)
        Log a message at the TRACE level according to the specified format and arguments.

        This form avoids superfluous string concatenation when the logger is disabled for the TRACE level. However, this variant incurs the hidden (and relatively small) cost of creating an Object[] before invoking the method, even if this logger is disabled for TRACE. The variants taking one and two arguments exist solely in order to avoid this hidden cost.

        Parameters:
        format - the format string
        arguments - a list of 3 or more arguments
        Since:
        1.4

      • trace

        void trace(String msg,
           Throwable t)
        Log an exception (throwable) at the TRACE level with an accompanying message.
        Parameters:
        msg - the message accompanying the exception
        t - the exception (throwable) to log
        Since:
        1.4

      • isTraceEnabled

        boolean isTraceEnabled(Marker marker)
        Similar to isTraceEnabled() method except that the marker data is also taken into account.
        Parameters:
        marker - The marker data to take into consideration
        Returns:
        True if this Logger is enabled for the TRACE level, false otherwise.
        Since:
        1.4

      • trace

        void trace(Marker marker,
           String msg)
        Log a message with the specific Marker at the TRACE level.
        Parameters:
        marker - the marker data specific to this log statement
        msg - the message string to be logged
        Since:
        1.4

      • trace

        void trace(Marker marker,
           String format,
           Object arg)
        This method is similar to trace(String, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg - the argument
        Since:
        1.4

      • trace

        void trace(Marker marker,
           String format,
           Object arg1,
           Object arg2)
        This method is similar to trace(String, Object, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg1 - the first argument
        arg2 - the second argument
        Since:
        1.4

      • trace

        void trace(Marker marker,
           String format,
           Object... argArray)
        This method is similar to trace(String, Object...) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        argArray - an array of arguments
        Since:
        1.4

      • trace

        void trace(Marker marker,
           String msg,
           Throwable t)
        This method is similar to trace(String, Throwable) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        msg - the message accompanying the exception
        t - the exception (throwable) to log
        Since:
        1.4

      • isDebugEnabled

        boolean isDebugEnabled()
        Is the logger instance enabled for the DEBUG level?
        Returns:
        True if this Logger is enabled for the DEBUG level, false otherwise.

      • debug

        void debug(String msg)
        Log a message at the DEBUG level.
        Parameters:
        msg - the message string to be logged

      • debug

        void debug(String format,
           Object arg)
        Log a message at the DEBUG level according to the specified format and argument.

        This form avoids superfluous object creation when the logger is disabled for the DEBUG level.

        Parameters:
        format - the format string
        arg - the argument

      • debug

        void debug(String format,
           Object arg1,
           Object arg2)
        Log a message at the DEBUG level according to the specified format and arguments.

        This form avoids superfluous object creation when the logger is disabled for the DEBUG level.

        Parameters:
        format - the format string
        arg1 - the first argument
        arg2 - the second argument

      • debug

        void debug(String format,
           Object... arguments)
        Log a message at the DEBUG level according to the specified format and arguments.

        This form avoids superfluous string concatenation when the logger is disabled for the DEBUG level. However, this variant incurs the hidden (and relatively small) cost of creating an Object[] before invoking the method, even if this logger is disabled for DEBUG. The variants taking one and two arguments exist solely in order to avoid this hidden cost.

        Parameters:
        format - the format string
        arguments - a list of 3 or more arguments

      • debug

        void debug(String msg,
           Throwable t)
        Log an exception (throwable) at the DEBUG level with an accompanying message.
        Parameters:
        msg - the message accompanying the exception
        t - the exception (throwable) to log

      • isDebugEnabled

        boolean isDebugEnabled(Marker marker)
        Similar to isDebugEnabled() method except that the marker data is also taken into account.
        Parameters:
        marker - The marker data to take into consideration
        Returns:
        True if this Logger is enabled for the DEBUG level, false otherwise.

      • debug

        void debug(Marker marker,
           String msg)
        Log a message with the specific Marker at the DEBUG level.
        Parameters:
        marker - the marker data specific to this log statement
        msg - the message string to be logged

      • debug

        void debug(Marker marker,
           String format,
           Object arg)
        This method is similar to debug(String, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg - the argument

      • debug

        void debug(Marker marker,
           String format,
           Object arg1,
           Object arg2)
        This method is similar to debug(String, Object, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg1 - the first argument
        arg2 - the second argument

      • debug

        void debug(Marker marker,
           String format,
           Object... arguments)
        This method is similar to debug(String, Object...) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arguments - a list of 3 or more arguments

      • debug

        void debug(Marker marker,
           String msg,
           Throwable t)
        This method is similar to debug(String, Throwable) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        msg - the message accompanying the exception
        t - the exception (throwable) to log

      • isInfoEnabled

        boolean isInfoEnabled()
        Is the logger instance enabled for the INFO level?
        Returns:
        True if this Logger is enabled for the INFO level, false otherwise.

      • info

        void info(String msg)
        Log a message at the INFO level.
        Parameters:
        msg - the message string to be logged

      • info

        void info(String format,
          Object arg)
        Log a message at the INFO level according to the specified format and argument.

        This form avoids superfluous object creation when the logger is disabled for the INFO level.

        Parameters:
        format - the format string
        arg - the argument

      • info

        void info(String format,
          Object arg1,
          Object arg2)
        Log a message at the INFO level according to the specified format and arguments.

        This form avoids superfluous object creation when the logger is disabled for the INFO level.

        Parameters:
        format - the format string
        arg1 - the first argument
        arg2 - the second argument

      • info

        void info(String format,
          Object... arguments)
        Log a message at the INFO level according to the specified format and arguments.

        This form avoids superfluous string concatenation when the logger is disabled for the INFO level. However, this variant incurs the hidden (and relatively small) cost of creating an Object[] before invoking the method, even if this logger is disabled for INFO. The variants taking one and two arguments exist solely in order to avoid this hidden cost.

        Parameters:
        format - the format string
        arguments - a list of 3 or more arguments

      • info

        void info(String msg,
          Throwable t)
        Log an exception (throwable) at the INFO level with an accompanying message.
        Parameters:
        msg - the message accompanying the exception
        t - the exception (throwable) to log

      • isInfoEnabled

        boolean isInfoEnabled(Marker marker)
        Similar to isInfoEnabled() method except that the marker data is also taken into consideration.
        Parameters:
        marker - The marker data to take into consideration
        Returns:
        true if this logger is warn enabled, false otherwise

      • info

        void info(Marker marker,
          String msg)
        Log a message with the specific Marker at the INFO level.
        Parameters:
        marker - The marker specific to this log statement
        msg - the message string to be logged

      • info

        void info(Marker marker,
          String format,
          Object arg)
        This method is similar to info(String, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg - the argument

      • info

        void info(Marker marker,
          String format,
          Object arg1,
          Object arg2)
        This method is similar to info(String, Object, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg1 - the first argument
        arg2 - the second argument

      • info

        void info(Marker marker,
          String format,
          Object... arguments)
        This method is similar to info(String, Object...) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arguments - a list of 3 or more arguments

      • info

        void info(Marker marker,
          String msg,
          Throwable t)
        This method is similar to info(String, Throwable) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data for this log statement
        msg - the message accompanying the exception
        t - the exception (throwable) to log

      • isWarnEnabled

        boolean isWarnEnabled()
        Is the logger instance enabled for the WARN level?
        Returns:
        True if this Logger is enabled for the WARN level, false otherwise.

      • warn

        void warn(String msg)
        Log a message at the WARN level.
        Parameters:
        msg - the message string to be logged

      • warn

        void warn(String format,
          Object arg)
        Log a message at the WARN level according to the specified format and argument.

        This form avoids superfluous object creation when the logger is disabled for the WARN level.

        Parameters:
        format - the format string
        arg - the argument

      • warn

        void warn(String format,
          Object... arguments)
        Log a message at the WARN level according to the specified format and arguments.

        This form avoids superfluous string concatenation when the logger is disabled for the WARN level. However, this variant incurs the hidden (and relatively small) cost of creating an Object[] before invoking the method, even if this logger is disabled for WARN. The variants taking one and two arguments exist solely in order to avoid this hidden cost.

        Parameters:
        format - the format string
        arguments - a list of 3 or more arguments

      • warn

        void warn(String format,
          Object arg1,
          Object arg2)
        Log a message at the WARN level according to the specified format and arguments.

        This form avoids superfluous object creation when the logger is disabled for the WARN level.

        Parameters:
        format - the format string
        arg1 - the first argument
        arg2 - the second argument

      • warn

        void warn(String msg,
          Throwable t)
        Log an exception (throwable) at the WARN level with an accompanying message.
        Parameters:
        msg - the message accompanying the exception
        t - the exception (throwable) to log

      • isWarnEnabled

        boolean isWarnEnabled(Marker marker)
        Similar to isWarnEnabled() method except that the marker data is also taken into consideration.
        Parameters:
        marker - The marker data to take into consideration
        Returns:
        True if this Logger is enabled for the WARN level, false otherwise.

      • warn

        void warn(Marker marker,
          String msg)
        Log a message with the specific Marker at the WARN level.
        Parameters:
        marker - The marker specific to this log statement
        msg - the message string to be logged

      • warn

        void warn(Marker marker,
          String format,
          Object arg)
        This method is similar to warn(String, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg - the argument

      • warn

        void warn(Marker marker,
          String format,
          Object arg1,
          Object arg2)
        This method is similar to warn(String, Object, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg1 - the first argument
        arg2 - the second argument

      • warn

        void warn(Marker marker,
          String format,
          Object... arguments)
        This method is similar to warn(String, Object...) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arguments - a list of 3 or more arguments

      • warn

        void warn(Marker marker,
          String msg,
          Throwable t)
        This method is similar to warn(String, Throwable) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data for this log statement
        msg - the message accompanying the exception
        t - the exception (throwable) to log

      • isErrorEnabled

        boolean isErrorEnabled()
        Is the logger instance enabled for the ERROR level?
        Returns:
        True if this Logger is enabled for the ERROR level, false otherwise.

      • error

        void error(String msg)
        Log a message at the ERROR level.
        Parameters:
        msg - the message string to be logged

      • error

        void error(String format,
           Object arg)
        Log a message at the ERROR level according to the specified format and argument.

        This form avoids superfluous object creation when the logger is disabled for the ERROR level.

        Parameters:
        format - the format string
        arg - the argument

      • error

        void error(String format,
           Object arg1,
           Object arg2)
        Log a message at the ERROR level according to the specified format and arguments.

        This form avoids superfluous object creation when the logger is disabled for the ERROR level.

        Parameters:
        format - the format string
        arg1 - the first argument
        arg2 - the second argument

      • error

        void error(String format,
           Object... arguments)
        Log a message at the ERROR level according to the specified format and arguments.

        This form avoids superfluous string concatenation when the logger is disabled for the ERROR level. However, this variant incurs the hidden (and relatively small) cost of creating an Object[] before invoking the method, even if this logger is disabled for ERROR. The variants taking one and two arguments exist solely in order to avoid this hidden cost.

        Parameters:
        format - the format string
        arguments - a list of 3 or more arguments

      • error

        void error(String msg,
           Throwable t)
        Log an exception (throwable) at the ERROR level with an accompanying message.
        Parameters:
        msg - the message accompanying the exception
        t - the exception (throwable) to log

      • isErrorEnabled

        boolean isErrorEnabled(Marker marker)
        Similar to isErrorEnabled() method except that the marker data is also taken into consideration.
        Parameters:
        marker - The marker data to take into consideration
        Returns:
        True if this Logger is enabled for the ERROR level, false otherwise.

      • error

        void error(Marker marker,
           String msg)
        Log a message with the specific Marker at the ERROR level.
        Parameters:
        marker - The marker specific to this log statement
        msg - the message string to be logged

      • error

        void error(Marker marker,
           String format,
           Object arg)
        This method is similar to error(String, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg - the argument

      • error

        void error(Marker marker,
           String format,
           Object arg1,
           Object arg2)
        This method is similar to error(String, Object, Object) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arg1 - the first argument
        arg2 - the second argument

      • error

        void error(Marker marker,
           String format,
           Object... arguments)
        This method is similar to error(String, Object...) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        format - the format string
        arguments - a list of 3 or more arguments

      • error

        void error(Marker marker,
           String msg,
           Throwable t)
        This method is similar to error(String, Throwable) method except that the marker data is also taken into consideration.
        Parameters:
        marker - the marker data specific to this log statement
        msg - the message accompanying the exception
        t - the exception (throwable) to log