filling pdf by itext

I read the pdf that contain of text field and I want to fill this field in the same pdf file that it oppened? what the sutible procedure?

I have the folloing statment but I do not want this can you correct my code depond on my request??? I want read the PDFform.pdf and I want fill the field in PDFform.pdf ( the changing in the same file).... How I can do my request!?

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import com.itextpdf.text.DocumentException;

import com.itextpdf.text.pdf.AcroFields;

import com.itextpdf.text.pdf.PdfReader;

import com.itextpdf.text.pdf.PdfStamper;

public class FillText {

    public static void main(String[] args) throws IOException,DocumentException 
    { 
        editField(); // call methode editField 
    } // end methode main

private static void editField() throws IOException,FileNotFoundException, DocumentException

{

// read an existing pdf file

PdfReader reader1 = new PdfReader("PDFform.pdf");

// I do not want the chang in the test.pdf .... I want the chang in PDFform.pdf

PdfStamper stamper = new PdfStamper(reader1, new FileOutputStream("test.pdf"));

stamper.getAcroFields().setField("Name", "She is work");

stamper.close();

reader1.close(); } // end methode

} // end class