Error handling in a GUI

[Dennis Grimbergen]

Hi,

I need a nice way to handle errors in a Swing GUI. Imagine a two-layered application (gui and database). A user clicks a button in the GUI, after which the database performs some action. Let's say a DatabaseException is thrown in the database code. Because I want to show a user friendly exception, I would assume something like this (in the GUI):

try {
    database.doSomethingTricky();
} catch(DatabaseException e) {
    throw new UserFriendlyException("Oops, something went wrong!");
}

From here it's not hard to show this thrown Exception in a alert box or something like that.

While searching the internet for some nice ways I noticed that something like this seems to be common?

try {
    database.doSomethingTricky();
} catch(DatabaseException e) {
    MyErrorHandler.showError(MyConstants.SOMETHING_WENT_WRONG);
}

Is this a correct way to deal with this? To me it seems not correct to use a static method (showError), from an OO perspective.

[Karthik Shiraly]

The design I usually follow is:

- translate API and framework exceptions to my own application defined (and related to application use cases) exceptions. For example, IOException to DiaryLoadException or DiarySaveException

- propagate these app defined exceptions all the way up so that other layers can take corrective actions if any (may help with requirements yet to come)

- At the highest layer of the application, catch and either log the exception, or pass it onto a view class for display. The display class uses the details in the exception (an integer ID is common in my apps) to form a locale specific error message and display it.

Can't say which approach is 'correct' because it's subjective. The above design has helped keep my apps flexible and extensible.