How to filter the results of content resolver in android?

Question

I would like to get user contacts and then append some kind of regular expression and append them to a list view. I am currently able to get all the contacts via

getContentResolver().query(People.CONTENT_URI, null, null, null, null);

and then pass them to a custom class that extends SimpleCursorAdapter.

So I would like to know how to get only the contacts that match a regular expression and not all of users contacts.

Answer 1

Instead of

getContentResolver().query(People.CONTENT_URI, null, null, null, null);  

you should use something like

final ContentResolver resolver = getContentResolver(); final String[] projection = { People._ID, People.NAME, People.NUMBER }; final String sa1 = "%A%"; // contains an "A" cursor = resolver.query(People.CONTENT_URI, projection, People.NAME + " LIKE ?",    new String[] { sa1 }, null); 

this uses a parameterized request (using ?) and provides the actual values as a different argument, this avoids concatenation and prevents SQL injection mainly if you are requesting the filter from the user. For example if you are using

cursor = resolver.query(People.CONTENT_URI, projection,    People.NAME + " = '" + name + "'",    new String[] { sa1 }, null); 

imagine if

name =  "Donald Duck' OR name = 'Mickey Mouse") // notice the " and ' 

and you are concatenating the strings.