import java.io.*;
import org.apache.poi.hwpf.HWPFDocument;
import org.apache.poi.hwpf.usermodel.CharacterRun;
import org.apache.poi.hwpf.usermodel.Range;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;

public class WriteInDocument{
public static void main(String[] args)throws IOException{
File file = new File("C:/sample.doc");
POIFSFileSystem fs = new POIFSFileSystem(new FileInputStream(file));
HWPFDocument doc = new HWPFDocument(fs);
Range range = doc.getRange();
CharacterRun run = range.insertAfter("Hello World!");
run.setFontSize(2 * 18);
run.setBold(true);
run.setItalic(true);
run.setCapitalized(true);
OutputStream out = new FileOutputStream(new File("C:/new.doc"));
doc.write(out);
out.flush();
out.close();
 }
}

For the above code, poi-scratchpad-3.7-20101029.jar is needed.

its not working correctly..font style is not getting changed. any1 tell me right method