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 Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	ROOT_LOGGER_NAME Case insensitive String constant used to retrieve the name of the root logger.

Method Summary

Modifier and Type	Method and Description
void	debug(Marker marker, java.lang.String msg) Log a message with the specific Marker at the DEBUG level.
void	debug(Marker marker, java.lang.String format, java.lang.Object... arguments) This method is similar to debug(String, Object...) method except that the marker data is also taken into consideration.
void	debug(Marker marker, java.lang.String format, java.lang.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, java.lang.String format, java.lang.Object arg1, java.lang.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, java.lang.String msg, java.lang.Throwable t) This method is similar to debug(String, Throwable) method except that the marker data is also taken into consideration.
void	debug(java.lang.String msg) Log a message at the DEBUG level.
void	debug(java.lang.String format, java.lang.Object... arguments) Log a message at the DEBUG level according to the specified format and arguments.
void	debug(java.lang.String format, java.lang.Object arg) Log a message at the DEBUG level according to the specified format and argument.
void	debug(java.lang.String format, java.lang.Object arg1, java.lang.Object arg2) Log a message at the DEBUG level according to the specified format and arguments.
void	debug(java.lang.String msg, java.lang.Throwable t) Log an exception (throwable) at the DEBUG level with an accompanying message.
void	error(Marker marker, java.lang.String msg) Log a message with the specific Marker at the ERROR level.
void	error(Marker marker, java.lang.String format, java.lang.Object... arguments) This method is similar to error(String, Object...) method except that the marker data is also taken into consideration.
void	error(Marker marker, java.lang.String format, java.lang.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, java.lang.String format, java.lang.Object arg1, java.lang.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, java.lang.String msg, java.lang.Throwable t) This method is similar to error(String, Throwable) method except that the marker data is also taken into consideration.
void	error(java.lang.String msg) Log a message at the ERROR level.
void	error(java.lang.String format, java.lang.Object... arguments) Log a message at the ERROR level according to the specified format and arguments.
void	error(java.lang.String format, java.lang.Object arg) Log a message at the ERROR level according to the specified format and argument.
void	error(java.lang.String format, java.lang.Object arg1, java.lang.Object arg2) Log a message at the ERROR level according to the specified format and arguments.
void	error(java.lang.String msg, java.lang.Throwable t) Log an exception (throwable) at the ERROR level with an accompanying message.
java.lang.String	getName() Return the name of this Logger instance.
void	info(Marker marker, java.lang.String msg) Log a message with the specific Marker at the INFO level.
void	info(Marker marker, java.lang.String format, java.lang.Object... arguments) This method is similar to info(String, Object...) method except that the marker data is also taken into consideration.
void	info(Marker marker, java.lang.String format, java.lang.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, java.lang.String format, java.lang.Object arg1, java.lang.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, java.lang.String msg, java.lang.Throwable t) This method is similar to info(String, Throwable) method except that the marker data is also taken into consideration.
void	info(java.lang.String msg) Log a message at the INFO level.
void	info(java.lang.String format, java.lang.Object... arguments) Log a message at the INFO level according to the specified format and arguments.
void	info(java.lang.String format, java.lang.Object arg) Log a message at the INFO level according to the specified format and argument.
void	info(java.lang.String format, java.lang.Object arg1, java.lang.Object arg2) Log a message at the INFO level according to the specified format and arguments.
void	info(java.lang.String msg, java.lang.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, java.lang.String msg) Log a message with the specific Marker at the TRACE level.
void	trace(Marker marker, java.lang.String format, java.lang.Object... argArray) This method is similar to trace(String, Object...) method except that the marker data is also taken into consideration.
void	trace(Marker marker, java.lang.String format, java.lang.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, java.lang.String format, java.lang.Object arg1, java.lang.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, java.lang.String msg, java.lang.Throwable t) This method is similar to trace(String, Throwable) method except that the marker data is also taken into consideration.
void	trace(java.lang.String msg) Log a message at the TRACE level.
void	trace(java.lang.String format, java.lang.Object... arguments) Log a message at the TRACE level according to the specified format and arguments.
void	trace(java.lang.String format, java.lang.Object arg) Log a message at the TRACE level according to the specified format and argument.
void	trace(java.lang.String format, java.lang.Object arg1, java.lang.Object arg2) Log a message at the TRACE level according to the specified format and arguments.
void	trace(java.lang.String msg, java.lang.Throwable t) Log an exception (throwable) at the TRACE level with an accompanying message.
void	warn(Marker marker, java.lang.String msg) Log a message with the specific Marker at the WARN level.
void	warn(Marker marker, java.lang.String format, java.lang.Object... arguments) This method is similar to warn(String, Object...) method except that the marker data is also taken into consideration.
void	warn(Marker marker, java.lang.String format, java.lang.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, java.lang.String format, java.lang.Object arg1, java.lang.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, java.lang.String msg, java.lang.Throwable t) This method is similar to warn(String, Throwable) method except that the marker data is also taken into consideration.
void	warn(java.lang.String msg) Log a message at the WARN level.
void	warn(java.lang.String format, java.lang.Object... arguments) Log a message at the WARN level according to the specified format and arguments.
void	warn(java.lang.String format, java.lang.Object arg) Log a message at the WARN level according to the specified format and argument.
void	warn(java.lang.String format, java.lang.Object arg1, java.lang.Object arg2) Log a message at the WARN level according to the specified format and arguments.
void	warn(java.lang.String msg, java.lang.Throwable t) Log an exception (throwable) at the WARN level with an accompanying message.

Field Detail

ROOT_LOGGER_NAME

static final java.lang.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

java.lang.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(java.lang.String msg)

Log a message at the TRACE level.

Parameters:

msg - the message string to be logged

Since:

1.4

trace

void trace(java.lang.String format,
           java.lang.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(java.lang.String format,
           java.lang.Object arg1,
           java.lang.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(java.lang.String format,
           java.lang.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(java.lang.String msg,
           java.lang.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,
           java.lang.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,
           java.lang.String format,
           java.lang.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,
           java.lang.String format,
           java.lang.Object arg1,
           java.lang.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,
           java.lang.String format,
           java.lang.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,
           java.lang.String msg,
           java.lang.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(java.lang.String msg)

Log a message at the DEBUG level.

Parameters:

msg - the message string to be logged

debug

void debug(java.lang.String format,
           java.lang.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(java.lang.String format,
           java.lang.Object arg1,
           java.lang.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(java.lang.String format,
           java.lang.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(java.lang.String msg,
           java.lang.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,
           java.lang.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,
           java.lang.String format,
           java.lang.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,
           java.lang.String format,
           java.lang.Object arg1,
           java.lang.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,
           java.lang.String format,
           java.lang.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,
           java.lang.String msg,
           java.lang.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(java.lang.String msg)

Log a message at the INFO level.

Parameters:

msg - the message string to be logged

info

void info(java.lang.String format,
          java.lang.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(java.lang.String format,
          java.lang.Object arg1,
          java.lang.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(java.lang.String format,
          java.lang.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(java.lang.String msg,
          java.lang.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,
          java.lang.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,
          java.lang.String format,
          java.lang.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,
          java.lang.String format,
          java.lang.Object arg1,
          java.lang.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,
          java.lang.String format,
          java.lang.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,
          java.lang.String msg,
          java.lang.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(java.lang.String msg)

Log a message at the WARN level.

Parameters:

msg - the message string to be logged

warn

void warn(java.lang.String format,
          java.lang.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(java.lang.String format,
          java.lang.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(java.lang.String format,
          java.lang.Object arg1,
          java.lang.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(java.lang.String msg,
          java.lang.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,
          java.lang.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,
          java.lang.String format,
          java.lang.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,
          java.lang.String format,
          java.lang.Object arg1,
          java.lang.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,
          java.lang.String format,
          java.lang.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,
          java.lang.String msg,
          java.lang.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(java.lang.String msg)

Log a message at the ERROR level.

Parameters:

msg - the message string to be logged

error

void error(java.lang.String format,
           java.lang.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(java.lang.String format,
           java.lang.Object arg1,
           java.lang.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(java.lang.String format,
           java.lang.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(java.lang.String msg,
           java.lang.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,
           java.lang.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,
           java.lang.String format,
           java.lang.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,
           java.lang.String format,
           java.lang.Object arg1,
           java.lang.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,
           java.lang.String format,
           java.lang.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,
           java.lang.String msg,
           java.lang.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