Question

Currently I’m using ContentProvider in my application. Because of “layers” and no actual need for provider – I’m working on optimizing data access as much as possible. Here is my attempt to do this:

public static String getPreferenceString(Context context, String key)
    {
        DatabaseHelper helper = new DatabaseHelper(context);
        SQLiteDatabase database = helper.getReadableDatabase();
        SQLiteStatement statement = database.compileStatement("SELECT Value FROM Preferences WHERE Key='" + key + "' LIMIT 1");

        try
        {
            return statement.simpleQueryForString();

        }
        catch (Exception ex)
        {
            return "";
        }
        finally
        {
            statement.close();
            database.close();
            helper.close();
        }
    }

    public static void setPreferenceString(Context context, String key, String value)
    {
        DatabaseHelper helper = new DatabaseHelper(context);
        SQLiteDatabase database = helper.getReadableDatabase();
        SQLiteStatement statement = database.compileStatement("INSERT OR REPLACE INTO Preferences (Key, UpdatedOn, Value) VALUES ('" +
                key + "', '" +
                Utility.getDateConvertedToUTCDBString(new Date()) + "', '" +
                value + "'); ");
        try
        {
            statement.execute();
        }
        finally
        {
            statement.close();
            database.close();
            helper.close();
        }
    }

1. Is that about as close as I can get to direct calls to SQLite?
2. Should I have all this .close() statements in my code?
3. In setPreferenceString I did copy/paste and called getReadableDatabase even though I write data and it works. Why?

Answer 1

Is that about as close as I can get to direct calls to SQLite?

AFAIK SQL queries are closest you can go against RDBs

Should I have all this .close() statements in my code?

Personally, I would not create a DatabaseHelper, an SQLiteDatabase, and an SQLiteStatement each time I call that method. I would create all this just before you need them, and close them when no needed anymore. Also centralizing this is a good idea IMHO (using a singleton, for example).

Also your SQL statement could be written like

SELECT Value FROM Preferences WHERE Key= ? LIMIT 1

This way you only have to prepare it once and bind parameters as you need the statement. Same goes for any SQL query.