Logger

java.lang.Object
- java.util.logging.Logger

```
public class Logger
extends Object
```
A Logger is used to log messages.
Loggers normally have a name, which is an arbitrary string. Named Loggers are created with the factory getLogger(String). This method will either create a new Logger or return a suitable existing Logger, using the name.
It also possible to create anonymous Loggers which are independent from the named Loggers and independent from one another.
Each Logger has an associated Level. This reflects a minimum level that this Logger will care about. If the level is high, the Logger will only care about important messages. When it low, it will care about more messages. Caring means logging. The Level can be changed dynamically, which is useful to augment or diminish the amount of messages that are actually logged.
The names of the logging methods, such as severe(String) or finer(String) denote the importance of the message. Their names match the standard levels given by the class Level. When using one of these methods, the Logger performs a test to compare its own Level and the Level associated with the logging request. If the level of the request is lower than the Logger's level, nothing happens. Otherwise, the Logger forwards the message to a list of Handlers that have been added with the method addHandler(Handler).

Field Summary

Fields
Modifier and Type	Field and Description
`protected Level`	`effectiveLevel` This is the real level of the logger.
`static String`	`GLOBAL_LOGGER_NAME` This is a name for the global logger.
`protected Level`	`publicLevel` This is the level set with `setLevel(Level)` and returned by `getLevel()`.

Constructor Summary

Constructors
Modifier Constructor and Description

protected Logger(String name, String resourceBundleName)
Protected method to create a logger.

Constructors
Modifier	Constructor and Description
`protected`	`Logger(String name, String resourceBundleName)` Protected method to create a logger.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addHandler(Handler handler)` Add a log Handler to the list of Handlers known by the Logger.
`void`	`config(String msg)` Log a CONFIG message.
`void`	`fine(String msg)` Log a FINE message.
`void`	`finer(String msg)` Log a FINER message.
`void`	`finest(String msg)` Log a FINEST message.
`static Logger`	`getAnonymousLogger()` Each call to this method creates a new Logger.
`static Logger`	`getGlobal()` Get the logger with the name Logger.GLOBAL_LOGGER_NAME.
`Level`	`getLevel()` Get the current level of this Logger.
`static Logger`	`getLogger(String name)` Find or create a logger.
`String`	`getName()` Get the name of this logger.
`Logger`	`getParent()` Get the parent of this logger.
`void`	`info(String msg)` Log an INFO message.
`boolean`	`isLoggable(Level level)` Check if a message of the given level would be logged by this Logger.
`void`	`log(Level level, String msg)` Log a message, with no arguments.
`void`	`log(Level level, String msg, Throwable thrown)` Log a message, with an associated throwable object.
`void`	`log(LogRecord record)` Log a LogRecord.
`void`	`removeHandler(Handler handler)` Remove the given Handler from the Logger's list.
`void`	`setLevel(Level newLevel)` Set the specified Level to the Logger.
`void`	`severe(String msg)` Log a SEVERE message.
`void`	`throwing(String sourceClass, String sourceMethod, Throwable thrown)` Log a that a method is terminating by throwing an Exception.
`void`	`warning(String msg)` Log a WARNING message.

Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - effectiveLevel
```
@Nullable
protected Level effectiveLevel
```
    This is the real level of the logger.
  - GLOBAL_LOGGER_NAME
```
public static final String GLOBAL_LOGGER_NAME
```
    This is a name for the global logger.
    
    See Also:
    
    Constant Field Values
  - publicLevel
```
@Nullable
protected Level publicLevel
```
    This is the level set with setLevel(Level) and returned by getLevel(). It may be null, that's why implementation will use the effectiveLevel to determine whether a message must be logged or not.
- Constructor Detail
  - Logger
```
protected Logger(@Nullable
                 String name,
                 @Nullable
                 String resourceBundleName)
```
    Protected method to create a logger. The second parameter is silently ignored, hence any call to this method is equivalent to getLogger(name, null).
    
    Parameters:
    
    name - used to identify the logger.
    
    resourceBundleName - not used.
- Method Detail
  - addHandler
```
public void addHandler(Handler handler)
```
    Add a log Handler to the list of Handlers known by the Logger.
    
    Parameters:
    
    handler - a new Handler for the Logger
  - config
```
public void config(@Nullable
                   String msg)
```
    Log a CONFIG message.
    If the logger is currently enabled for the CONFIG message level then the given message is forwarded to all the registered output handler objects.
    
    Parameters:
    
    msg - message to log.
  - fine
```
public void fine(@Nullable
                 String msg)
```
    Log a FINE message.
    If the logger is currently enabled for the FINE message level then the given message is forwarded to all the registered output handler objects.
    
    Parameters:
    
    msg - message to log.
  - finer
```
public void finer(@Nullable
                  String msg)
```
    Log a FINER message.
    If the logger is currently enabled for the FINER message level then the given message is forwarded to all the registered output handler objects.
    
    Parameters:
    
    msg - message to log.
  - finest
```
public void finest(@Nullable
                   String msg)
```
    Log a FINEST message.
    If the logger is currently enabled for the FINEST message level then the given message is forwarded to all the registered output handler objects.
    
    Parameters:
    
    msg - message to log.
  - getAnonymousLogger
```
public static Logger getAnonymousLogger()
```
    Each call to this method creates a new Logger. Its level is set to Level.ALL. An anonymous logger is not registered in the LogManager.
    
    Returns:
    
    a new anonymous Logger, whose name is null
  - getGlobal
```
public static final Logger getGlobal()
```
    Get the logger with the name Logger.GLOBAL_LOGGER_NAME.
    
    Returns:
    
    the global logger
  - getLevel
```
@Nullable
public Level getLevel()
```
    Get the current level of this Logger.
    
    Returns:
    
    the Logger's current level.
  - getLogger
```
public static Logger getLogger(String name)
```
    Find or create a logger.
    If a logger has already been with the same name, this logger is returned (note that case is not taken into account). Otherwise a new logger is created.
    If a new logger is created its log level will be configured based on the LogManager configuration and it will configured to also send logging output to its parent's handlers. It will be registered in the LogManager global namespace.
    Note: The LogManager may only retain a weak reference to the newly created logger. It is important to understand that a previously created logger with the given name may be garbage collected at any time if there is no strong reference to the Logger. In particular, this means that two back-to-back calls like getLogger("MyLogger").log(...) may use different Logger objects named "MyLogger" if there is no strong reference to the Logger named "MyLogger" elsewhere in the program.
    
    Parameters:
    
    name - used to identify a logger. Case is not taken into account.
    
    Returns:
    
    a suitable Logger.
    
    Throws:
    
    NullPointerException - if name is null.
  - getName
```
@Nullable
public String getName()
```
    Get the name of this logger. It is the name used for its creation or null for anonymous Loggers.
    
    Returns:
    
    the Logger's name (or null for anonymous Loggers).
  - getParent
```
@Nullable
public Logger getParent()
```
    Get the parent of this logger.
    
    Returns:
    
    the parent of this logger; null for the root logger
  - info
```
public void info(@Nullable
                 String msg)
```
    Log an INFO message.
    If the logger is currently enabled for the INFO message level then the given message is forwarded to all the registered output handler objects.
    
    Parameters:
    
    msg - message to log.
  - isLoggable
```
public boolean isLoggable(Level level)
```
    Check if a message of the given level would be logged by this Logger. This depends on the Logger current level. If the Logger's current level is lower than 'level', the message would be logged ; otherwise, it would not.
    
    Parameters:
    
    level - a logging Level.
    
    Returns:
    
    true if the message would be logged.
  - log
```
public void log(Level level,
                @Nullable
                String msg)
```
    Log a message, with no arguments. If the logger is currently enabled for the given message level then the given message is forwarded to all the registered output Handler objects.
    
    Parameters:
    
    level - One of the message level identifiers, e.g. SEVERE
    
    msg - The string message (or a key in the message catalog)
  - log
```
public void log(Level level,
                @Nullable
                String msg,
                @Nullable
                Throwable thrown)
```
    Log a message, with an associated throwable object. If the logger is currently enabled for the given message level then the given message is forwarded to all the registered output Handler objects.
    
    Parameters:
    
    level - One of the message level identifiers, e.g. SEVERE
    
    msg - The string message (or a key in the message catalog)
    
    thrown - The throwable associated with the message
  - log
```
public void log(LogRecord record)
```
    Log a LogRecord.
    
    Parameters:
    
    record - the log record to publish
  - removeHandler
```
public void removeHandler(Handler handler)
```
    Remove the given Handler from the Logger's list. If the Handlers is null or is not know by the Logger, then the method does nothing.
    
    Parameters:
    
    handler - the Handler to remove
  - setLevel
```
public void setLevel(@Nullable
                     Level newLevel)
```
    Set the specified Level to the Logger. This level specifies which message levels will be logged by this Logger from now on.
    Level.OFF can be used to turn off logging.
    
    Parameters:
    
    newLevel - the new Level for the Logger (may be null)
  - severe
```
public void severe(@Nullable
                   String msg)
```
    Log a SEVERE message.
    If the logger is currently enabled for the SEVERE message level then the given message is forwarded to all the registered output handler objects.
    
    Parameters:
    
    msg - message to log.
  - throwing
```
public void throwing(String sourceClass,
                     String sourceMethod,
                     Throwable thrown)
```
    Log a that a method is terminating by throwing an Exception. The level FINER is used.
    
    Parameters:
    
    sourceClass - name of the class that requested the log
    
    sourceMethod - name of the method inside this class
    
    thrown - the throwable being thrown
  - warning
```
public void warning(@Nullable
                    String msg)
```
    Log a WARNING message.
    If the logger is currently enabled for the WARNING message level then the given message is forwarded to all the registered output handler objects.
    
    Parameters:
    
    msg - message to log.

Class Logger

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

effectiveLevel

GLOBAL_LOGGER_NAME

publicLevel

Constructor Detail

Logger

Method Detail

addHandler

config

fine

finer

finest

getAnonymousLogger

getGlobal

getLevel

getLogger

getName

getParent

info

isLoggable

log

log

log

removeHandler

setLevel

severe

throwing

warning