org.slf4j
Interface Logger

All Known Subinterfaces:
LocationAwareLogger
All Known Implementing Classes:
JCLLoggerAdapter, JDK14LoggerAdapter, LocLogger, Log4jLoggerAdapter, LoggerWrapper, MarkerIgnoringBase, NOPLogger, SimpleLogger, SubstituteLogger, XLogger

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.

Author:
Ceki Gülcü

Field Summary
static String ROOT_LOGGER_NAME
          Case insensitive String constant used to retrieve the name of the root logger.
 
Method Summary
 void debug(Marker marker, String msg)
          Log a message with the specific Marker at the DEBUG level.
 void debug(Marker marker, String format, Object... arguments)
          This method is similar to debug(String, Object...)
 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.
 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.
 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.
 void debug(String msg)
          Log a message at the DEBUG level.
 void debug(String format, Object... arguments)
          Log a message at the DEBUG level according to the specified format and arguments.
 void debug(String format, Object arg)
          Log a message at the DEBUG level according to the specified format and argument.
 void debug(String format, Object arg1, Object arg2)
          Log a message at the DEBUG level according to the specified format and arguments.
 void debug(String msg, Throwable t)
          Log an exception (throwable) at the DEBUG level with an accompanying message.
 void error(Marker marker, String msg)
          Log a message with the specific Marker at the ERROR level.
 void error(Marker marker, String format, Object... arguments)
          This method is similar to error(String, Object...)
 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.
 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.
 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.
 void error(String msg)
          Log a message at the ERROR level.
 void error(String format, Object... arguments)
          Log a message at the ERROR level according to the specified format and arguments.
 void error(String format, Object arg)
          Log a message at the ERROR level according to the specified format and argument.
 void error(String format, Object arg1, Object arg2)
          Log a message at the ERROR level according to the specified format and arguments.
 void error(String msg, Throwable t)
          Log an exception (throwable) at the ERROR level with an accompanying message.
 String getName()
          Return the name of this Logger instance.
 void info(Marker marker, String msg)
          Log a message with the specific Marker at the INFO level.
 void info(Marker marker, String format, Object... arguments)
          This method is similar to info(String, Object...)
 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.
 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.
 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.
 void info(String msg)
          Log a message at the INFO level.
 void info(String format, Object... arguments)
          Log a message at the INFO level according to the specified format and arguments.
 void info(String format, Object arg)
          Log a message at the INFO level according to the specified format and argument.
 void info(String format, Object arg1, Object arg2)
          Log a message at the INFO level according to the specified format and arguments.
 void info(String msg, Throwable t)
          Log an exception (throwable) at the INFO level with an accompanying message.
 boolean isDebugEnabled()
          Is the logger instance enabled for the DEBUG level?
 boolean isDebugEnabled(Marker marker)
          Similar to isDebugEnabled() method except that the marker data is also taken into account.
 boolean isErrorEnabled()
          Is the logger instance enabled for the ERROR level?
 boolean isErrorEnabled(Marker marker)
          Similar to isErrorEnabled() method except that the marker data is also taken into consideration.
 boolean isInfoEnabled()
          Is the logger instance enabled for the INFO level?
 boolean isInfoEnabled(Marker marker)
          Similar to isInfoEnabled() method except that the marker data is also taken into consideration.
 boolean isTraceEnabled()
          Is the logger instance enabled for the TRACE level?
 boolean isTraceEnabled(Marker marker)
          Similar to isTraceEnabled() method except that the marker data is also taken into account.
 boolean isWarnEnabled()
          Is the logger instance enabled for the WARN level?
 boolean isWarnEnabled(Marker marker)
          Similar to isWarnEnabled() method except that the marker data is also taken into consideration.
 void trace(Marker marker, String msg)
          Log a message with the specific Marker at the TRACE level.
 void trace(Marker marker, String format, Object... argArray)
          This method is similar to trace(String, Object...)
 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.
 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.
 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.
 void trace(String msg)
          Log a message at the TRACE level.
 void trace(String format, Object... arguments)
          Log a message at the TRACE level according to the specified format and arguments.
 void trace(String format, Object arg)
          Log a message at the TRACE level according to the specified format and argument.
 void trace(String format, Object arg1, Object arg2)
          Log a message at the TRACE level according to the specified format and arguments.
 void trace(String msg, Throwable t)
          Log an exception (throwable) at the TRACE level with an accompanying message.
 void warn(Marker marker, String msg)
          Log a message with the specific Marker at the WARN level.
 void warn(Marker marker, String format, Object... arguments)
          This method is similar to warn(String, Object...)
 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.
 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.
 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.
 void warn(String msg)
          Log a message at the WARN level.
 void warn(String format, Object... arguments)
          Log a message at the WARN level according to the specified format and arguments.
 void warn(String format, Object arg)
          Log a message at the WARN level according to the specified format and argument.
 void warn(String format, Object arg1, Object arg2)
          Log a message at the WARN level according to the specified format and arguments.
 void warn(String msg, Throwable t)
          Log an exception (throwable) at the WARN level with an accompanying message.
 

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


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