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LocalizedError.javaAPI DocExample3524Sat Jan 24 10:44:30 GMT 2004je3.i18n

LocalizedError

public class LocalizedError extends Object
A convenience class that can display a localized exception message depending on the class of the exception. It uses a MessageFormat, and passes five arguments that the localized message may include: {0}: the message included in the exception or error. {1}: the full class name of the exception or error. {2}: the file the exception occurred in {3}: a line number in that file. {4}: the current date and time. Messages are looked up in a ResourceBundle with the basename "Errors", using a the full class name of the exception object as the resource name. If no resource is found for a given exception class, the superclasses are checked.

Fields Summary
Constructors Summary
Methods Summary
public static voiddisplay(java.lang.Throwable error)

        ResourceBundle bundle;
        // Try to get the resource bundle.
        // If none, print the error in a non-localized way.
        try {
	    String bundleName = "com.davidflanagan.examples.i18n.Errors";
	    bundle = ResourceBundle.getBundle(bundleName);
	}
        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; }
	
	// Get the filename and linenumber for the exception
	// In Java 1.4, this is easy, but in prior releases, we had to try
	// parsing the output Throwable.printStackTrace();
	StackTraceElement frame = error.getStackTrace()[0];  // Java 1.4
	String filename = frame.getFileName();
	int linenum = frame.getLineNumber();

        // 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.err.println(MessageFormat.format(message, args));
public static voidmain(java.lang.String[] 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

	try { FileReader in = new FileReader(args[0]); }
	catch(Exception e) { LocalizedError.display(e);	}