If cursor.moveToFirst()
returns false do I still need to close it?
Since it returns false when the cursor is empty.
I'm doubt about the correct approach:
if (cursor != null && cursor.moveToFirst()) {
// some code
cursor.close();
}
Or:
if(cursor != null) {
if (cursor.moveToFirst()) {
// some code
}
cursor.close();
}
You must close all
Cursors
which are not nulls, regardless of whether they have populated entries or not.The only exception to the above statement would be if you know that the
Cursor
in question is managed by some "external" framework and will be automatically closed without your interaction (as is the case withLoaderManager
framework when used withCursorLoader
).At least two (good) reasons to close any non-null
Cursor
:Cursors
can have "memory-allocations" which need to be explicitly released even if they are empty (as is the case withAbstractWindowedCursor
)Cursor
can become non-empty ifrequery()
is called. Your means to prevent this explicitly is to close theCursor
The most general and error prone approach would be (it is an overkill in some cases):
Another popular pattern if you need to iterate over
Cursor's
entries:Don't feel bad with one extra
c != null
comparison - it is totally justified in these cases.