iText PDF中的Java Unicode字符

Question

我正在尝试在我的Android App Studio生成的PDF中添加一些特殊字符，但是除了°，在iText生成的pdf中看不到任何字符。请帮忙！

Document doc = new Document(PageSize.A4, 15f, 15f, 35f, 25f);
String outPath = Environment.getExternalStorageDirectory()+"/Bar_Fixed_Compressive.pdf";
try {
     PdfWriter pdfWriter = PdfWriter.getInstance(doc, new FileOutputStream(outPath));
     doc.open();
     doc.add(new Paragraph("On increase in the temperature of the bar by " +mEditText4b1113.getText().toString() +"\u00B0 C, the uniform thermal " +
                            "strain is given by, \n " +"\u03B5 =" +"\u03B1" +"x T " ));
     doc.close();
}