public class

Logger

extends Object
java.lang.Object
   ↳ java.util.logging.Logger

Class Overview

Loggers are used to log records to certain outputs, including file, console, etc. They use various handlers to actually do the output-dependent operations.

Client applications can get named loggers by calling the getLogger methods. They can also get anonymous loggers by calling the getAnonymousLogger methods. Named loggers are organized in a namespace hierarchy managed by a log manager. The naming convention is usually the same as java package's naming convention, that is using dot-separated strings. Anonymous loggers do not belong to any namespace.

Loggers "inherit" log level setting from their parent if their own level is set to null. This is also true for the resource bundle. The logger's resource bundle is used to localize the log messages if no resource bundle name is given when a log method is called. If getUseParentHandlers() returns true, loggers also inherit their parent's handlers. In this context, "inherit" only means that "behavior" is inherited. The internal field values will not change, for example, getLevel() still returns null.

When loading a given resource bundle, the logger first tries to use the context classloader. If that fails, it tries the system classloader. And if that still fails, it searches up the class stack and uses each class's classloader to try to locate the resource bundle.

Some log methods accept log requests that do not specify the source class and source method. In these cases, the logging framework will automatically infer the calling class and method, but this is not guaranteed to be accurate.

Once a LogRecord object has been passed into the logging framework, it is owned by the logging framework and the client applications should not use it any longer.

All methods of this class are thread-safe.

See Also

Summary

Constants
Logger global The global logger is provided as convenience for casual use.
Protected Constructors
Logger(String name, String resourceBundleName)
Constructs a Logger object with the supplied name and resource bundle name; notifiyParentHandlers is set to true.
Public Methods
void addHandler(Handler handler)
Adds a handler to this logger.
void config(String msg)
Logs a message of level Level.CONFIG; the message is transmitted to all subscribed handlers.
void entering(String sourceClass, String sourceMethod, Object[] params)
Logs a message indicating that a method has been entered.
void entering(String sourceClass, String sourceMethod, Object param)
Logs a message indicating that a method has been entered.
void entering(String sourceClass, String sourceMethod)
Logs a message indicating that a method has been entered.
void exiting(String sourceClass, String sourceMethod, Object result)
Logs a message indicating that a method is exited.
void exiting(String sourceClass, String sourceMethod)
Logs a message indicating that a method is exited.
void fine(String msg)
Logs a message of level Level.FINE; the message is transmitted to all subscribed handlers.
void finer(String msg)
Logs a message of level Level.FINER; the message is transmitted to all subscribed handlers.
void finest(String msg)
Logs a message of level Level.FINEST; the message is transmitted to all subscribed handlers.
static Logger getAnonymousLogger()
Gets an anonymous logger to use internally in a thread.
static Logger getAnonymousLogger(String resourceBundleName)
Gets an anonymous logger to use internally in a thread.
Filter getFilter()
Gets the filter used by this logger.
Handler[] getHandlers()
Gets all the handlers associated with this logger.
Level getLevel()
Gets the logging level of this logger.
static Logger getLogger(String name)
Gets a named logger.
static Logger getLogger(String name, String resourceBundleName)
Gets a named logger associated with the supplied resource bundle.
String getName()
Gets the name of this logger, null for anonymous loggers.
Logger getParent()
Gets the nearest parent of this logger in the namespace, a null value will be returned if called on the root logger.
ResourceBundle getResourceBundle()
Gets the loaded resource bundle used by this logger to localize logging messages.
String getResourceBundleName()
Gets the name of the loaded resource bundle used by this logger to localize logging messages.
boolean getUseParentHandlers()
Gets the flag which indicates whether to use the handlers of this logger's parent to publish incoming log records, potentially recursively up the namespace.
void info(String msg)
Logs a message of level Level.INFO; the message is transmitted to all subscribed handlers.
boolean isLoggable(Level l)
Determines whether this logger will actually log messages of the specified level.
void log(Level logLevel, String msg, Throwable thrown)
Logs a message of the specified level with the supplied Throwable object.
void log(Level logLevel, String msg, Object[] params)
Logs a message of the specified level with the supplied parameter array.
void log(Level logLevel, String msg)
Logs a message of the specified level.
void log(Level logLevel, String msg, Object param)
Logs a message of the specified level with the supplied parameter.
void log(LogRecord record)
Logs a given log record.
void logp(Level logLevel, String sourceClass, String sourceMethod, String msg, Object[] params)
Logs a message of the given level with the specified source class name, source method name and parameter array.
void logp(Level logLevel, String sourceClass, String sourceMethod, String msg)
Logs a message of the given level with the specified source class name and source method name.
void logp(Level logLevel, String sourceClass, String sourceMethod, String msg, Object param)
Logs a message of the given level with the specified source class name, source method name and parameter.
void logp(Level logLevel, String sourceClass, String sourceMethod, String msg, Throwable thrown)
Logs a message of the given level with the specified source class name, source method name and Throwable object.
void logrb(Level logLevel, String sourceClass, String sourceMethod, String bundleName, String msg)
Logs a message of the given level with the specified source class name and source method name, using the given resource bundle to localize the message.
void logrb(Level logLevel, String sourceClass, String sourceMethod, String bundleName, String msg, Throwable thrown)
Logs a message of the given level with the specified source class name, source method name and Throwable object, using the given resource bundle to localize the message.
void logrb(Level logLevel, String sourceClass, String sourceMethod, String bundleName, String msg, Object param)
Logs a message of the given level with the specified source class name, source method name and parameter, using the given resource bundle to localize the message.
void logrb(Level logLevel, String sourceClass, String sourceMethod, String bundleName, String msg, Object[] params)
Logs a message of the given level with the specified source class name, source method name and parameter array, using the given resource bundle to localize the message.
void removeHandler(Handler handler)
Removes a handler from this logger.
void setFilter(Filter newFilter)
Sets the filter used by this logger.
void setLevel(Level newLevel)
Sets the logging level for this logger.
void setParent(Logger parent)
Sets the parent of this logger in the namespace.
void setUseParentHandlers(boolean notifyParentHandlers)
Sets the flag which indicates whether to use the handlers of this logger's parent, potentially recursively up the namespace.
void severe(String msg)
Logs a message of level Level.SEVERE; the message is transmitted to all subscribed handlers.
void throwing(String sourceClass, String sourceMethod, Throwable thrown)
Logs a message indicating that an exception is thrown.
void warning(String msg)
Logs a message of level Level.WARNING; the message is transmitted to all subscribed handlers.
[Expand]
Inherited Methods
From class java.lang.Object

Constants

public static final Logger global

Since: API Level 1

The global logger is provided as convenience for casual use.

Protected Constructors

protected Logger (String name, String resourceBundleName)

Since: API Level 1

Constructs a Logger object with the supplied name and resource bundle name; notifiyParentHandlers is set to true.

Notice : Loggers use a naming hierarchy. Thus "z.x.y" is a child of "z.x".

Parameters
name the name of this logger, may be null for anonymous loggers.
resourceBundleName the name of the resource bundle used to localize logging messages, may be null.
Throws
MissingResourceException if the specified resource bundle can not be loaded.

Public Methods

public void addHandler (Handler handler)

Since: API Level 1

Adds a handler to this logger. The name will be fed with log records received by this logger.

Parameters
handler the handler object to add, cannot be null.
Throws
SecurityException if a security manager determines that the caller does not have the required permission.

public void config (String msg)

Since: API Level 1

Logs a message of level Level.CONFIG; the message is transmitted to all subscribed handlers.

Parameters
msg the message to log.

public void entering (String sourceClass, String sourceMethod, Object[] params)

Since: API Level 1

Logs a message indicating that a method has been entered. A log record with log level Level.FINER, log message "ENTRY", the specified source class name, source method name and array of parameters is submitted for logging.

Parameters
sourceClass the source class name.
sourceMethod the source method name.
params an array of parameters for the method call.

public void entering (String sourceClass, String sourceMethod, Object param)

Since: API Level 1

Logs a message indicating that a method has been entered. A log record with log level Level.FINER, log message "ENTRY", the specified source class name, source method name and one parameter is submitted for logging.

Parameters
sourceClass the source class name.
sourceMethod the source method name.
param the parameter for the method call.

public void entering (String sourceClass, String sourceMethod)

Since: API Level 1

Logs a message indicating that a method has been entered. A log record with log level Level.FINER, log message "ENTRY", the specified source class name and source method name is submitted for logging.

Parameters
sourceClass the calling class name.
sourceMethod the method name.

public void exiting (String sourceClass, String sourceMethod, Object result)

Since: API Level 1

Logs a message indicating that a method is exited. A log record with log level Level.FINER, log message "RETURN", the specified source class name, source method name and return value is submitted for logging.

Parameters
sourceClass the source class name.
sourceMethod the source method name.
result the return value of the method call.

public void exiting (String sourceClass, String sourceMethod)

Since: API Level 1

Logs a message indicating that a method is exited. A log record with log level Level.FINER, log message "RETURN", the specified source class name and source method name is submitted for logging.

Parameters
sourceClass the calling class name.
sourceMethod the method name.

public void fine (String msg)

Since: API Level 1

Logs a message of level Level.FINE; the message is transmitted to all subscribed handlers.

Parameters
msg the message to log.

public void finer (String msg)

Since: API Level 1

Logs a message of level Level.FINER; the message is transmitted to all subscribed handlers.

Parameters
msg the message to log.

public void finest (String msg)

Since: API Level 1

Logs a message of level Level.FINEST; the message is transmitted to all subscribed handlers.

Parameters
msg the message to log.

public static Logger getAnonymousLogger ()

Since: API Level 1

Gets an anonymous logger to use internally in a thread. Anonymous loggers are not registered in the log manager's namespace. No security checks will be performed when updating an anonymous logger's control settings.

The anonymous loggers' parent is set to be the root logger. This way it inherits the default logging level and handlers from the root logger.

Returns
  • a new instance of anonymous logger.

public static Logger getAnonymousLogger (String resourceBundleName)

Since: API Level 1

Gets an anonymous logger to use internally in a thread. Anonymous loggers are not registered in the log manager's namespace. No security checks will be performed when updating an anonymous logger's control settings.

The anonymous loggers' parent is set to be the root logger. This way it inherits default logging level and handlers from the root logger.

Parameters
resourceBundleName the name of the resource bundle used to localize log messages.
Returns
  • a new instance of anonymous logger.
Throws
MissingResourceException if the specified resource bundle can not be loaded.

public Filter getFilter ()

Since: API Level 1

Gets the filter used by this logger.

Returns
  • the filter used by this logger, may be null.

public Handler[] getHandlers ()

Since: API Level 1

Gets all the handlers associated with this logger.

Returns
  • an array of all the handlers associated with this logger.

public Level getLevel ()

Since: API Level 1

Gets the logging level of this logger. A null level indicates that this logger inherits its parent's level.

Returns
  • the logging level of this logger.

public static Logger getLogger (String name)

Since: API Level 1

Gets a named logger. The returned logger may already exist or may be newly created. In the latter case, its level will be set to the configured level according to the LogManager's properties.

Parameters
name the name of the logger to get, cannot be null.
Returns
  • a named logger.
Throws
MissingResourceException If the specified resource bundle can not be loaded.

public static Logger getLogger (String name, String resourceBundleName)

Since: API Level 1

Gets a named logger associated with the supplied resource bundle. The resource bundle will be used to localize logging messages.

Parameters
name the name of the logger to get, cannot be null.
resourceBundleName the name of the resource bundle, may be null.
Returns
  • a named logger.
Throws
IllegalArgumentException if the logger identified by name is associated with a resource bundle and its name is not equal to resourceBundleName.
MissingResourceException if the name of the resource bundle cannot be found.

public String getName ()

Since: API Level 1

Gets the name of this logger, null for anonymous loggers.

Returns
  • the name of this logger.

public Logger getParent ()

Since: API Level 1

Gets the nearest parent of this logger in the namespace, a null value will be returned if called on the root logger.

Returns
  • the parent of this logger in the namespace.

public ResourceBundle getResourceBundle ()

Since: API Level 1

Gets the loaded resource bundle used by this logger to localize logging messages. If the value is null, the parent's resource bundle will be inherited.

Returns
  • the loaded resource bundle used by this logger.

public String getResourceBundleName ()

Since: API Level 1

Gets the name of the loaded resource bundle used by this logger to localize logging messages. If the value is null, the parent's resource bundle name will be inherited.

Returns
  • the name of the loaded resource bundle used by this logger.

public boolean getUseParentHandlers ()

Since: API Level 1

Gets the flag which indicates whether to use the handlers of this logger's parent to publish incoming log records, potentially recursively up the namespace.

Returns
  • true if set to use parent's handlers, false otherwise.

public void info (String msg)

Since: API Level 1

Logs a message of level Level.INFO; the message is transmitted to all subscribed handlers.

Parameters
msg the message to log.

public boolean isLoggable (Level l)

Since: API Level 1

Determines whether this logger will actually log messages of the specified level. The effective level used to do the determination may be inherited from its parent. The default level is Level.INFO.

Parameters
l the level to check.
Returns
  • true if this logger will actually log this level, otherwise false.

public void log (Level logLevel, String msg, Throwable thrown)

Since: API Level 1

Logs a message of the specified level with the supplied Throwable object. The message is then transmitted to all subscribed handlers.

Parameters
logLevel the level of the given message.
msg the message to log.
thrown the Throwable object associated with the event that is logged.

public void log (Level logLevel, String msg, Object[] params)

Since: API Level 1

Logs a message of the specified level with the supplied parameter array. The message is then transmitted to all subscribed handlers.

Parameters
logLevel the level of the given message
msg the message to log.
params the parameter array associated with the event that is logged.

public void log (Level logLevel, String msg)

Since: API Level 1

Logs a message of the specified level. The message is transmitted to all subscribed handlers.

Parameters
logLevel the level of the specified message.
msg the message to log.

public void log (Level logLevel, String msg, Object param)

Since: API Level 1

Logs a message of the specified level with the supplied parameter. The message is then transmitted to all subscribed handlers.

Parameters
logLevel the level of the given message.
msg the message to log.
param the parameter associated with the event that is logged.

public void log (LogRecord record)

Since: API Level 1

Logs a given log record. Only records with a logging level that is equal or greater than this logger's level will be submitted to this logger's handlers for logging. If getUseParentHandlers() returns true, the log record will also be submitted to the handlers of this logger's parent, potentially recursively up the namespace.

Since all other log methods call this method to actually perform the logging action, subclasses of this class can override this method to catch all logging activities.

Parameters
record the log record to be logged.

public void logp (Level logLevel, String sourceClass, String sourceMethod, String msg, Object[] params)

Since: API Level 1

Logs a message of the given level with the specified source class name, source method name and parameter array.

Parameters
logLevel the level of the given message.
sourceClass the source class name.
sourceMethod the source method name.
msg the message to be logged.
params the parameter array associated with the event that is logged.

public void logp (Level logLevel, String sourceClass, String sourceMethod, String msg)

Since: API Level 1

Logs a message of the given level with the specified source class name and source method name.

Parameters
logLevel the level of the given message.
sourceClass the source class name.
sourceMethod the source method name.
msg the message to be logged.

public void logp (Level logLevel, String sourceClass, String sourceMethod, String msg, Object param)

Since: API Level 1

Logs a message of the given level with the specified source class name, source method name and parameter.

Parameters
logLevel the level of the given message
sourceClass the source class name
sourceMethod the source method name
msg the message to be logged
param the parameter associated with the event that is logged.

public void logp (Level logLevel, String sourceClass, String sourceMethod, String msg, Throwable thrown)

Since: API Level 1

Logs a message of the given level with the specified source class name, source method name and Throwable object.

Parameters
logLevel the level of the given message.
sourceClass the source class name.
sourceMethod the source method name.
msg the message to be logged.
thrown the Throwable object.

public void logrb (Level logLevel, String sourceClass, String sourceMethod, String bundleName, String msg)

Since: API Level 1

Logs a message of the given level with the specified source class name and source method name, using the given resource bundle to localize the message. If bundleName is null, the empty string or not valid then the message is not localized.

Parameters
logLevel the level of the given message.
sourceClass the source class name.
sourceMethod the source method name.
bundleName the name of the resource bundle used to localize the message.
msg the message to be logged.

public void logrb (Level logLevel, String sourceClass, String sourceMethod, String bundleName, String msg, Throwable thrown)

Since: API Level 1

Logs a message of the given level with the specified source class name, source method name and Throwable object, using the given resource bundle to localize the message. If bundleName is null, the empty string or not valid then the message is not localized.

Parameters
logLevel the level of the given message
sourceClass the source class name
sourceMethod the source method name
bundleName the name of the resource bundle used to localize the message.
msg the message to be logged.
thrown the Throwable object.

public void logrb (Level logLevel, String sourceClass, String sourceMethod, String bundleName, String msg, Object param)

Since: API Level 1

Logs a message of the given level with the specified source class name, source method name and parameter, using the given resource bundle to localize the message. If bundleName is null, the empty string or not valid then the message is not localized.

Parameters
logLevel the level of the given message.
sourceClass the source class name.
sourceMethod the source method name.
bundleName the name of the resource bundle used to localize the message.
msg the message to be logged.
param the parameter associated with the event that is logged.

public void logrb (Level logLevel, String sourceClass, String sourceMethod, String bundleName, String msg, Object[] params)

Since: API Level 1

Logs a message of the given level with the specified source class name, source method name and parameter array, using the given resource bundle to localize the message. If bundleName is null, the empty string or not valid then the message is not localized.

Parameters
logLevel the level of the given message.
sourceClass the source class name.
sourceMethod the source method name.
bundleName the name of the resource bundle used to localize the message.
msg the message to be logged.
params the parameter array associated with the event that is logged.

public void removeHandler (Handler handler)

Since: API Level 1

Removes a handler from this logger. If the specified handler does not exist then this method has no effect.

Parameters
handler the handler to be removed.
Throws
SecurityException if a security manager determines that the caller does not have the required permission.

public void setFilter (Filter newFilter)

Since: API Level 1

Sets the filter used by this logger.

Parameters
newFilter the filter to set, may be null.
Throws
SecurityException if a security manager determines that the caller does not have the required permission.

public void setLevel (Level newLevel)

Since: API Level 1

Sets the logging level for this logger. A null level indicates that this logger will inherit its parent's level.

Parameters
newLevel the logging level to set.
Throws
SecurityException if a security manager determines that the caller does not have the required permission.

public void setParent (Logger parent)

Since: API Level 1

Sets the parent of this logger in the namespace. This method should be used by the LogManager object only.

Parameters
parent the parent logger to set.
Throws
SecurityException if a security manager determines that the caller does not have the required permission.

public void setUseParentHandlers (boolean notifyParentHandlers)

Since: API Level 1

Sets the flag which indicates whether to use the handlers of this logger's parent, potentially recursively up the namespace.

Parameters
notifyParentHandlers the new flag indicating whether to use the parent's handlers.
Throws
SecurityException if a security manager determines that the caller does not have the required permission.

public void severe (String msg)

Since: API Level 1

Logs a message of level Level.SEVERE; the message is transmitted to all subscribed handlers.

Parameters
msg the message to log.

public void throwing (String sourceClass, String sourceMethod, Throwable thrown)

Since: API Level 1

Logs a message indicating that an exception is thrown. A log record with log level Level.FINER, log message "THROW", the specified source class name, source method name and the Throwable object is submitted for logging.

Parameters
sourceClass the source class name.
sourceMethod the source method name.
thrown the Throwable object.

public void warning (String msg)

Since: API Level 1

Logs a message of level Level.WARNING; the message is transmitted to all subscribed handlers.

Parameters
msg the message to log.