Wrong character on conversion PDF to TXT

I am trying to convert PDF to TXT and some PDF, after converted, the String present wrong character. Could be UNICODE problem ? Can somebody help me ?

I oberved that the problem when try to convert PDF, created by PDFCreator, in Text. The character are wrong. Any suggesting ?

the code

public class PDFTextParser {

PDFParser parser;
String parsedText;
PDFTextStripper pdfStripper;
PDDocument pdDoc;
COSDocument cosDoc;
PDDocumentInformation pdDocInfo;

// PDFTextParser Constructor
public PDFTextParser() {
}

// Extract text from PDF Document
public String pdftoText(String fileName) {

System.out.println("Parsing text from PDF file " + fileName + "....");
File f = new File(fileName);

if (!f.isFile())

{ System.out.println("File " + fileName + " does not exist."); return null; }

try

{ parser = new PDFParser(new FileInputStream(f)); }

catch (Exception e)

{ System.out.println("Unable to open PDF Parser."); return null; }

try

{ parser.parse(); cosDoc = parser.getDocument(); pdfStripper = new PDFTextStripper(); pdDoc = new PDDocument(cosDoc); parsedText = pdfStripper.getText(pdDoc); }

catch (Exception e) {
System.out.println("An exception occured in parsing the PDF Document.");
e.printStackTrace();
try

{ if (cosDoc != null) cosDoc.close(); if (pdDoc != null) pdDoc.close(); }

catch (Exception e1)

{ e.printStackTrace(); }

return null;
}
System.out.println("Done.");
return parsedText;
}