Write Double value in numeric cell with specific format in Apache Poi 3.7

Question

I need to write a Double value in a numeric cell using a specific format, i mean, the generated xls must have numeric cells containing Double values like, for example: 8,1.

Answer 1

Do you need to put both values in one cell? Can you split them up into 2 columns? Excel has a built-in "Texts to Columns" function that you should be able to reference that will split an entire column of text strings into multiple columns based on a delimiter (like a comma). In VBA, it looks something like this:

Selection.TextToColumns Destination:=Range("A1"), DataType:=xlDelimited, _
TextQualifier:=xlDoubleQuote, ConsecutiveDelimiter:=False, Tab:=False, _
Semicolon:=False, Comma:=True, Space:=False, Other:=False, FieldInfo _
:=Array(Array(1, 1), Array(2, 1)), TrailingMinusNumbers:=True

As for your first proposed solution, it is not possible to force Excel to treat something as a number if it is not convertable to a number.