posted 13 years ago
'a' is table of primitives.
'a1' and 'b1' are tables of objects (Boolean, Integer, Char, Number etc. etc. are all descendants of Object).
Cells of table of primitive booleans are initialized to 'false'.
Cells of table of Objects (Booleans, Integers, Bytes, Longs etc.) are initialized to null.
When you try to access a table cell which is initialized to null, you get NullPioterException.