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Grace Software
JavaLog
$Revision: 1.4 $
$Date: 1999/10/11 00:05:13 $
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public static void error(Exception); public static void error(String message); public static void error(String message, Object userData); public static void error(String message, Exception);The first of these functions is the most useful for handling exceptions. It can be used as follows:
try { ... code that throws an exception ... } catch (Exception e) { grace.log.Log.error(e); }The second of these functions can be used if an error has occurred but there is no exception to accompany it:
if (can_not_open_file) { grace.log.Log.error("can't open file"); }The third function is useful also where there is no exception to accompany the error but it allows the caller to log an object in the log:
if (!object.isValid()) { grace.log.Log.error("invalid object state", object); }
public static void warning(String message); public static void warning(String message, Object userData); public static void warning(String message, Exception);These functions are identical to their "error" counterparts other than the fact that they log a warning instead of an error.
public static void notice(String message); public static void notice(String message, Object userData);These functions allow the user to log information. They allows the programmer to write a simple message or a message and a user object. These messages should always be intended to be read by the user of the program (i.e. not just the programmer).
grace.log.Log.notice("program is operational");
public static void trace(); public static void trace(String message); public static void trace(Object userData); public static void trace(String message, Object userData);Tracing is intended as a debugging tool for the programmer. Log output is normally disabled in the normal operation of the program. The following example simply logs the entry and exit from a function called "cancel".
public void cancel(Flight flight) { grace.log.Log.trace("begin", flight); ... grace.log.Log.trace("end"); }
public static void log(String eventType, String message); public static void log(String eventType, Object userData); public static void log(String eventType, String message, Object userData);The above three functions allow the programmer to log events that are of any event type. In these functions, the eventType is passed as a user defined string. Using the event types "Error", "Warning", "Notice", or "Trace" is equivalent to calling the Log.error(), Log.warning(), Log.notice(), or Log.trace() function, respectively.
double transactionRate; ... grace.log.Log.log("statistics", "transaction-rate=" + transactionRate);Note, in the above code, the transactionRate double variable is appended to the "transaction-rate=" string instead of passing it as userData. This is because the Log interfaces do not accept primitive types currently. This may be an addition in the future.