Edit

We can edit a PDF, we have to create a new copy from original.

private static String sInPutfile = "Android/data/Example.pdf";
    private static String sOutPutFile = "Android/data/ExampleCopy.pdf";

Then we have to PdfReader and PdfStamper, you can check the library iText.

private void editPDF(String string) {

        try {

            FileInputStream is = new FileInputStream(mPdfFile);
            PdfReader pdfReader = new PdfReader(is);
            PdfStamper pdfStamper = new PdfStamper(pdfReader,
                    new FileOutputStream(mPdfFileOutPut));

            for (int i = 1; i <= pdfReader.getNumberOfPages(); i++) {

                //create content from pdfStamper
                PdfContentByte content = pdfStamper.getUnderContent(i);

                // Text over the existing page
                BaseFont bf = BaseFont.createFont(BaseFont.HELVETICA,
                        BaseFont.WINANSI, BaseFont.EMBEDDED);

                content.beginText();
                //set the font
                content.setFontAndSize(bf, 18);
                content.showTextAligned(PdfContentByte.ALIGN_LEFT, string, 430, 15, 0);
                content.endText();

            }

            pdfStamper.close();

        } catch (IOException e) {
            e.printStackTrace();

        } catch (DocumentException e) {
            e.printStackTrace();

        }

    }

And we can edit the PDF generated other PDF in android.

Example in Github