Why android.database.DatabaseUtils does not throw exceptions such as SQLException?

Question

I'm getting started with Android app development and I am extremely surprised that an API like android.database.DatabaseUtils does not throw exceptions upwards when using its methods. I wonder what is the reason for, what I consider, a bad design. (There must be a reason..)

As an example here

with the method long execute()

public long execute() {

  if (mPreparedStatement == null) {
    throw new IllegalStateException("you must prepare this inserter before calling "+ "execute");
  }
  try {
    if (LOCAL_LOGV) Log.v(TAG, "--- doing insert or replace in table " + mTableName);
    return mPreparedStatement.executeInsert();
  } catch (SQLException e) {
    Log.e(TAG, "Error executing InsertHelper with table " + mTableName, e);
    return -1;
   } finally {
   // you can only call this once per prepare
   mPreparedStatement = null;
  }
}

So this method is catching the SQLException and, instead throwing towards the invoker this or another wrapped Exception, it is simply returning -1 and logging the error with logcat.

As a developer I find this quite shocking as if I am using this API and I get a value -1 I know that something went wrong but I don't know why something went wrong unless I check the logcat logs.

Maybe I'm mistaken, please let me know, but an API with a method that returns -1 for an operation is a poorly OO design when it could simple throw an exception if something goes wrong and let the developer handle that exception in the way he/she wants extracting all the details from the Exception object. Don't you think?

Is there any reason to do it that way?

I have integrated logback with my application and I was hoping not to need to use logcat for anything. But after seeing this API I'm afraid I will have to, somehow, export a filtered logcat into a file to see what went wrong when my app received a -1 executing something on SQLlite.

Any advise please? Am I missing something here?

Much appreciated!

score 3 · Answer 1 · edited May 23 '17 at 11:57

First, we are not Google engineers who wrote the code in the first place nor mind readers. We cannot know for sure why a piece of code was designed the way it was. But we can make educated guesses. Consider the following:

The database APIs build on top of sqlite3 C library. C has no exceptions and exceptional error conditions are signalled by other means, such as returning a special value such as -1.
From design point of view, an API in android.database package throwing an exception android.database.sqlite package would be exposing unnecessary implementation detail. ( Though there are other methods that expose such detail by using SQL* classes.) Wrapping the detailed exception in an API level exception as you mention would be better.
"Utils" classes in general tend not to be designed really. They are just collection of methods the developers found to be needing often. You don't have to use them.
Exception handling is relatively expensive in terms of performance. Returning a special value is much cheaper. Avoiding exceptions can be a good idea especially in low level code that gets executed often. Though this point is not that relevant for the code you linked since it contains a try-catch block in it.
Overall, Android sqlite APIs are not particularly exemplary design. I've written about some of its oddities before, for example here.

Why android.database.DatabaseUtils does not throw exceptions such as SQLException?

1 Answers1