SimpleFormatter

AI-generated Key Takeaways

• SimpleFormatter provides a human-readable summary of log records, typically in 1-2 lines.

• It uses a format string, configurable via system properties or logging properties, to define the output structure.

• The default format is implementation-specific if the java.util.logging.SimpleFormatter.format property is undefined or invalid.

• The format string utilizes the java.util.Formatter syntax and can include date, source, logger name, level, message, and throwable information.

• SimpleFormatter can be extended for custom formatting by overriding the format method.

public class SimpleFormatter extends Formatter

Print a brief summary of the LogRecord in a human readable format. The summary will typically be 1 or 2 lines.

Configuration: The SimpleFormatter is initialized with the format string specified in the java.util.logging.SimpleFormatter.format property to {@linkplain #format format} the log messages. This property can be defined in the {@linkplain LogManager#getProperty logging properties} configuration file or as a system property. If this property is set in both the logging properties and system properties, the format string specified in the system property will be used. If this property is not defined or the given format string is {@linkplain java.util.IllegalFormatException illegal}, the default format is implementation-specific.

See Also

• Formatter

Public Constructor Summary

SimpleFormatter()

Public Method Summary

synchronized String

format(LogRecord record) Format the given LogRecord.

Inherited Method Summary

From class java.util.logging.Formatter

abstract String	format(LogRecord record) Format the given log record and return the formatted string.
synchronized String	formatMessage(LogRecord record) Localize and format the message string from a log record.
String	getHead(Handler h) Return the header string for a set of formatted records.
String	getTail(Handler h) Return the tail string for a set of formatted records.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Public Constructors

public SimpleFormatter ()

Public Methods

public synchronized String format (LogRecord record)

Format the given LogRecord.

The formatting can be customized by specifying the format string in the java.util.logging.SimpleFormatter.format property. The given LogRecord will be formatted as if by calling:

    String.format(format, date, source, logger, level, message, thrown);
 

where the arguments are:

1. format - the java.util.Formatter format string specified in the java.util.logging.SimpleFormatter.format property or the default format.
2. date - a Date object representing {@linkplain LogRecord#getMillis event time} of the log record.
3. source - a string representing the caller, if available; otherwise, the logger's name.
4. logger - the logger's name.
5. level - the {@linkplain Level#getLocalizedName log level}.
6. message - the formatted log message returned from the Formatter.formatMessage(LogRecord) method. It uses java.text formatting and does not use the java.util.Formatter format argument.
7. thrown - a string representing the {@linkplain LogRecord#getThrown throwable} associated with the log record and its backtrace beginning with a newline character, if any; otherwise, an empty string.

Some example formats:

• java.util.logging.SimpleFormatter.format="%4$s: %5$s [%1$tc]%n"

  This prints 1 line with the log level (4$), the log message (5$) and the timestamp (1$) in a square bracket.

       WARNING: warning message [Tue Mar 22 13:11:31 PDT 2011]
       

• java.util.logging.SimpleFormatter.format="%1$tc %2$s%n%4$s: %5$s%6$s%n"

  This prints 2 lines where the first line includes the timestamp (1$) and the source (2$); the second line includes the log level (4$) and the log message (5$) followed with the throwable and its backtrace (6$), if any:

       Tue Mar 22 13:11:31 PDT 2011 MyClass fatal
       SEVERE: several message with an exception
       java.lang.IllegalArgumentException: invalid argument
               at MyClass.mash(MyClass.java:9)
               at MyClass.crunch(MyClass.java:6)
               at MyClass.main(MyClass.java:3)
       

• java.util.logging.SimpleFormatter.format="%1$tb %1$td, %1$tY %1$tl:%1$tM:%1$tS %1$Tp %2$s%n%4$s: %5$s%n"

  This prints 2 lines similar to the example above with a different date/time formatting and does not print the throwable and its backtrace:

       Mar 22, 2011 1:11:31 PM MyClass fatal
       SEVERE: several message with an exception
       

This method can also be overridden in a subclass. It is recommended to use the Formatter.formatMessage(LogRecord) convenience method to localize and format the message field.

Parameters

record	the log record to be formatted.

Returns

• a formatted log record