Module java.base

Package java.lang

Interface System.Logger

Enclosing class:

System

public static interface System.Logger

System.Logger instances log messages that will be routed to the underlying logging framework the LoggerFinder uses. System.Logger instances are typically obtained from the System class, by calling System.getLogger(loggerName) or System.getLogger(loggerName, bundle).

Since:

9

See Also:

• System.getLogger(java.lang.String)
• System.getLogger(java.lang.String, java.util.ResourceBundle)
• System.LoggerFinder

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static enum	System.Logger.Level	System loggers levels.

Method Summary

Modifier and Type	Method	Description
String	getName()	Returns the name of this logger.
boolean	isLoggable(System.Logger.Level level)	Checks if a message of the given level would be logged by this logger.
default void	log(System.Logger.Level level, Object obj)	Logs a message produced from the given object.
default void	log(System.Logger.Level level, String msg)	Logs a message.
default void	log(System.Logger.Level level, String format, Object... params)	Logs a message with an optional list of parameters.
default void	log(System.Logger.Level level, String msg, Throwable thrown)	Logs a message associated with a given throwable.
default void	log(System.Logger.Level level, Supplier<String> msgSupplier)	Logs a lazily supplied message.
default void	log(System.Logger.Level level, Supplier<String> msgSupplier, Throwable thrown)	Logs a lazily supplied message associated with a given throwable.
void	log(System.Logger.Level level, ResourceBundle bundle, String format, Object... params)	Logs a message with resource bundle and an optional list of parameters.
void	log(System.Logger.Level level, ResourceBundle bundle, String msg, Throwable thrown)	Logs a localized message associated with a given throwable.

Method Details

getName

String getName()

Returns the name of this logger.

Returns:

the logger name.

isLoggable

boolean isLoggable(System.Logger.Level level)

Checks if a message of the given level would be logged by this logger.

Parameters:

level - the log message level.

Returns:

true if the given log message level is currently being logged.

Throws:

NullPointerException - if level is null.

log

default void log(System.Logger.Level level,
 String msg)

Logs a message.

Implementation Requirements:

The default implementation for this method calls this.log(level, (ResourceBundle)null, msg, (Object[])null);

Parameters:

level - the log message level.

msg - the string message (or a key in the message catalog, if this logger is a localized logger); can be null.

Throws:

NullPointerException - if level is null.

log

default void log(System.Logger.Level level,
 Supplier<String> msgSupplier)

Logs a lazily supplied message. If the logger is currently enabled for the given log message level then a message is logged that is the result produced by the given supplier function. Otherwise, the supplier is not operated on.

Implementation Requirements:

When logging is enabled for the given level, the default implementation for this method calls this.log(level, (ResourceBundle)null, msgSupplier.get(), (Object[])null);

Parameters:

level - the log message level.

msgSupplier - a supplier function that produces a message.

Throws:

NullPointerException - if level is null, or msgSupplier is null.

log

default void log(System.Logger.Level level,
 Object obj)

Logs a message produced from the given object. If the logger is currently enabled for the given log message level then a message is logged that, by default, is the result produced from calling toString on the given object. Otherwise, the object is not operated on.

Implementation Requirements:

When logging is enabled for the given level, the default implementation for this method calls this.log(level, (ResourceBundle)null, obj.toString(), (Object[])null);

Parameters:

level - the log message level.

obj - the object to log.

Throws:

NullPointerException - if level is null, or obj is null.

log

default void log(System.Logger.Level level,
 String msg,
 Throwable thrown)

Logs a message associated with a given throwable.

Implementation Requirements:

The default implementation for this method calls this.log(level, (ResourceBundle)null, msg, thrown);

Parameters:

level - the log message level.

msg - the string message (or a key in the message catalog, if this logger is a localized logger); can be null.

thrown - a Throwable associated with the log message; can be null.

Throws:

NullPointerException - if level is null.

log

default void log(System.Logger.Level level,
 Supplier<String> msgSupplier,
 Throwable thrown)

Logs a lazily supplied message associated with a given throwable. If the logger is currently enabled for the given log message level then a message is logged that is the result produced by the given supplier function. Otherwise, the supplier is not operated on.

Implementation Requirements:

When logging is enabled for the given level, the default implementation for this method calls this.log(level, (ResourceBundle)null, msgSupplier.get(), thrown);

Parameters:

level - one of the log message level identifiers.

msgSupplier - a supplier function that produces a message.

thrown - a Throwable associated with log message; can be null.

Throws:

NullPointerException - if level is null, or msgSupplier is null.

log

default void log(System.Logger.Level level,
 String format,
 Object... params)

Logs a message with an optional list of parameters.

Implementation Requirements:

The default implementation for this method calls this.log(level, (ResourceBundle)null, format, params);

Parameters:

level - one of the log message level identifiers.

format - the string message format in MessageFormat format, (or a key in the message catalog, if this logger is a localized logger); can be null.

params - an optional list of parameters to the message (may be none).

Throws:

NullPointerException - if level is null.

log

void log(System.Logger.Level level,
 ResourceBundle bundle,
 String msg,
 Throwable thrown)

Logs a localized message associated with a given throwable. If the given resource bundle is non-null, the msg string is localized using the given resource bundle. Otherwise the msg string is not localized.

Parameters:

level - the log message level.

bundle - a resource bundle to localize msg; can be null.

msg - the string message (or a key in the message catalog, if bundle is not null); can be null.

thrown - a Throwable associated with the log message; can be null.

Throws:

NullPointerException - if level is null.

log

void log(System.Logger.Level level,
 ResourceBundle bundle,
 String format,
 Object... params)

Logs a message with resource bundle and an optional list of parameters. If the given resource bundle is non-null, the format string is localized using the given resource bundle. Otherwise the format string is not localized.

Parameters:

level - the log message level.

bundle - a resource bundle to localize format; can be null.

format - the string message format in MessageFormat format, (or a key in the message catalog if bundle is not null); can be null.

params - an optional list of parameters to the message (may be none).

Throws:

NullPointerException - if level is null.