How to Converting large Text to PDF so all the text fits on the same page

Question

I try reading a text file and then generate a pdf from the text but the resulting PDF does not contain all the text.

Here is a snippet of my code:

PDDocument document = new PDDocument();

PDPage page = new PDPage();
document.addPage(page);

PDPageContentStream contentStream = new PDPageContentStream(document,page);
contentStream.beginText();
contentStream.setFont(PDType1Font.HELVETICA, 14);
contentStream.newLineAtOffset(25, 700);
contentStream.setLeading(18f);

while ((line = reader.readLine()) != null) {
    contentStream.showText(line);
    contentStream.newLine();
}

contentStream.endText();
contentStream.close();

document.save(targetPath);
document.close();