Java Reference
In-Depth Information
Example 7−5: LocalizedError.java (continued)
// If none, print the error in a non-localized way.
try { bundle = ResourceBundle.getBundle("Errors"); }
catch (MissingResourceException e) {
error.printStackTrace(System.err);
return;
}
// Look up a localized message resource in that bundle, using the
// classname of the error (or its superclasses) as the resource name.
// If no resource was found, display the error without localization.
String message = null;
Class c = error.getClass();
while((message == null) && (c != Object.class)) {
try { message = bundle.getString(c.getName()); }
catch (MissingResourceException e) { c = c.getSuperclass(); }
}
if (message == null) { error.printStackTrace(System.err); return; }
// Try to figure out the filename and line number of the
// exception. Output the error's stack trace into a string, and
// use the heuristic that the first line number that appears in
// the stack trace is after the first or second colon. We assume that
// this stack frame is the first one the programmer has any control
// over, and so report it as the location of the exception.
// Note that this is implementation-dependent and not robust...
String filename = "";
int linenum = 0;
try {
StringWriter sw = new StringWriter(); // Output stream to a string.
PrintWriter out=new PrintWriter(sw); // PrintWriter wrapper.
error.printStackTrace(out); // Print stacktrace.
String trace = sw.toString(); // Get it as a string.
int pos = trace.indexOf(':'); // Look for first colon.
if (error.getMessage() != null) // If the error has a message
pos = trace.indexOf(':', pos+1); // look for second colon.
int pos2 = trace.indexOf(')', pos); // Look for end of line #
linenum = Integer.parseInt(trace.substring(pos+1,pos2)); // line #
pos2 = trace.lastIndexOf('(', pos); // Back to start of filename.
filename = trace.substring(pos2+1, pos); // Get filename.
}
catch (Exception e) { ; }
// Ignore exceptions.
// Set up an array of arguments to use with the message
String errmsg = error.getMessage();
Object[] args = {
((errmsg!= null)?errmsg:""), error.getClass().getName(),
filename, new Integer(linenum), new Date()
};
// Finally, display the localized error message, using
// MessageFormat.format() to substitute the arguments into the message.
System.out.println(MessageFormat.format(message, args));
}
/**
* This is a simple test program that demonstrates the display() method.
* You can use it to generate and display a FileNotFoundException or an
* ArrayIndexOutOfBoundsException
**/
