ExceptionDialog
What the user sees when code threw. It shows a box with the message you passed as its title, and what it puts inside depends on whether anything recognises the exception.
try {
save();
} catch(Exception x) {
ExceptionDialog.create(this, "Saving the order failed", x);
}
Showing one
| Method | What it does |
|---|---|
ExceptionDialog.create(NodeContainer, String message, Throwable) |
show the exception in a box |
ExceptionDialog.createIgnore(NodeContainer, String message, Throwable) |
the same, but a failure while making the box is logged instead of thrown |
node.executeWithDialog(String message, IExecute) |
run the code, show the dialog if it threw, and return false in that case |
executeWithDialog is on NodeContainer, so it is available on every page and
component; it is the try/catch above, written once:
cp.add(new DefaultButton("Save", () -> executeWithDialog("Saving the order failed", () -> save())));
A ValidationException is ignored on purpose: the control that threw it has
already put its message on the screen, and a box on top of that would say the
same thing twice.
What ends up in the box
The exception is unwrapped out of any WrappedException and offered to the
registered translators - functions from an exception to an
ExceptionPresentation, which is either a sentence or a piece of DOM. The first
one that returns something decides what is shown. If none of them recognise it,
the exception is logged as an error and the box shows its toString() and its
stack trace.
| Exception | What the user sees instead of a stack trace |
|---|---|
CodeException, MessageException |
the message of the exception, translated |
QConcurrentUpdateException, JPA's OptimisticLockException |
"somebody else changed this data" |
a SQLException with SQL state 23505, BetterSQLException |
the message of the database error |
Your own exceptions get the same treatment by registering a translator:
ExceptionDialog.register(x -> x instanceof OutOfStockException osx
? new ExceptionPresentation(Msg.orderOutOfStock.format(osx.getAlbum()))
: null);
The list is global and the last translator registered is asked first, so
this belongs in the initialize() of your DomApplication - it is a decision of
the application, not of a page.
Exceptions that nobody catches at all do not reach this class; they are handled by the exception listeners of the application, which telling something to a user describes.