NPE when transcoding data that contains un-mapped chars

Michael Lockhart — Tue, 19 Aug 2008 01:23:56 -0000

When testing the filter function using an input file, the program crashed with Null Pointer Exception.

-- Condition
run dvorcode to decode or encode an input file
-- Expected Result
output produced either encoded or decoded as requested
-- Actual Result
Null Pointer Exception in call to String.replace()

-- Investigation

This is due to the replace call being supplied a Null String reference. When the Map is asked to retrieve a character which is not a key, it returns Null.

-- Resolution

Rather than have a COMMON_STRING that contains all characters in common between encodings, use the Map's own predicates to guard string replacement.

That is, replace the guarding code that does a String.contains() with a call to Map.containsKey()

Recent changes to bugs

NPE when transcoding data that contains un-mapped chars