How to read and write a HashMap to a file?

Question

I have the following HashMap:

HashMap fileObj = new HashMap();

ArrayList cols         


        

Answer 1

Your first line:

HashMap fileObj = new HashMap();

gave me pause, as the values are not guaranteed to be Serializable and thus may not be written out correctly. You should really define the object as a HashMap (or if you prefer, simpy Map).

I would also consider serializing the Map in a simple text format such as JSON since you are doing a simple String -> List mapping.