The exception message
U+0009 ('controlHT') is not available in this font Helvetica (generic: ArialMT) encoding: WinAnsiEncoding
means that the string you draw contains a character for which the font (in particular in its selected encoding) provides no glyph drawing instructions.
It even indicates which character is the culprit: "U+0009 ('controlHT')", i.e. a control character, the horizontal tab. Indeed, control characters have to be avoided as hardly any font will contain glyphs for them.
As you already have confirmed in the comments to your question
string.replaceAll("\t", " ")
worked fine for me
So horizontal tabs seem to have been the only problem characters.