hi Mark

howdy, Julius!

how can I help you today?

I have a question, but expected it to be busy and have to compose it

nope, pretty quiet

I was wondering if it's possible to combine the reults of two Cursors

define "combine"

I have a list and it will get data from two places: 1. a ContentProvider and 2. a SQLiteDatabase

(At the moment the only thing I can think of is to copy all the data from the ContentProvider's db to my db which seems wrong! :))

meaning that you want a single ListView containing one Cursor's data, followed by the other Cursor's data?

well I was hoping to combine both

it's for music

so I have good meta data in my db for some music

again, I need you to define "combine"

and I have the meta data for the music on the device itself which varies in quality depending on how it was encoded

oh right

uh ok so I have a list of say songs and usually I would create a query and get a Cursor and supply an ordered cursor to the adapter (for the list)

so now I would like to have a Cursor which is populated with data from both sources

and what will you do with the Cursor?

and when you say "populated with data from both sources", is this an append operation, a SQL-style JOIN, or something else?

supply it to a CursorAdapter which will be set for the ListActivity (eg.)

and when you say "populated with data from both sources", is this an append operation, a SQL-style JOIN, or something else?

that's the question really, I'm not sure how to combine the data from the two different dources

sources

OK, this is frustrating, so hang on while I try to explain

(sorry!)

let's say you have Cursor A and Cursor B

and you are aiming for a "combined" Cursor C

yes

there are probably millions of possible ways to "combine" A and B to get C

oh I didn't realise that

for example, C could be the data from A, followed by the data from B, assuming they both have the same column layout

or, C could have the same number of rows as A, but have extra columns obtained from B

or, C could have the same number of rows as B, but have extra columns obtained from A

oh I see

they'll have different numbers of rows

(almost every time)

OK

is Cursor C then the combination of A's rows and B's rows?

and the columns could be different too - but they should share some attributes

er columns

yes

then you cannot have Cursor C

well, OK

you could do a SQL-ish full outer join or something

why do you want them in one Cursor? isn't the goal to have them in one ListView?

can't you achieve that by two CursorAdapters, concatenated via a MergeAdapter?

I figured with the Cursor I could manipulate the combined dataset more easily so I coul then say order the combination by title or create date

well, you'd have to build a MatrixCursor

basically, assemble the 2D array yourself

that will be slow and memory intensive for lots of rows, though

ah ok MergeAdapter looks like it might e the way to go

how much data are you anticipating?

hundreds

depends on how many mp3 files a person has

that might be tolerable

you'd have to try it with a MatrixCursor

of course, you could also just assemble the stuff into POJOs and use an ArrayAdapter, then

I'll take a look at those two options thank you - apologies for not being clearer :)

(it wouldn't be a problem if I didn't need to sort the combination I coul just tack the result of one onto the other)

Looking forward to reading any updates of your books (and sections I haven't yet read) at the beach after christmas.

See you again soon :)

see ya!