How to handle SQLiteException in Android activity?

Question

I am looking at how to handle exceptions in Android.

In the update() function in the sample code for the Notepad Content Provider, it calls getWriteableDatabase(), which can potentially throw an SQLiteException.

I notice that the NoteEditor Activity saveNote() function has the following code:

// Commit all of our changes to persistent storage. When the update completes
// the content provider will notify the cursor of the change, which will
// cause the UI to be updated.
try {
   getContentResolver().update(mUri, values, null, null);
 } catch (NullPointerException e) {
     Log.e(TAG, e.getMessage());
 }

What happens if an SQLiteException occurs?. I want to be able to catch this exception in the Activity and display an appropriate message to the user (via a toast or something similar).

I thought I could do by adding an extra catch for SQLiteException. However, I read the following info in the Google docs:

"Remember that the Android system must be able to communicate the Exception across process boundaries. Android can do this for the following exceptions that may be useful in >handling query errors:

IllegalArgumentException (You may choose to throw this if your provider receives an >invalid content URI)

NullPointerException"

So I am now confused - can I catch the SQLiteException or not?

Answer 1

Whenever possible, you should catch the Exception in the class or component in which the Exception occurred. Use some sort of broadcast mechanism or return value semantics to report errors across processes.

It's admittedly a tricky situation. Some people say that if an SQLite (or other Exception) occurs in a ContentProvider, the provider should propagate the exception upwards instead of returning null in the Cursor. However, this generally won't work across processes! On the other hand, returning null doesn't give you a lot of information.

A limited set of Exceptions do traverse process boundaries, but SQLiteException isn't among them - still they might be useful/appropriate.