So which of these is your question?
(1) Why doesn't POI automatically set the width of columns to the number I am thinking of?
(2) How do I set the width of an Excel column in POI?
(3) Can POI set the width of an Excel column?
(4) How do I figure out what number to use for the width of a column?
(5) Why doesn't POI set the width of the column to the number I told it to use?
(6) ...
In other words: if you want people on the forum to help, then "what should be done" is that
you should formulate a clear question. Have a look at our FAQ link
TellTheDetails for more information.