How to find and replace text in word files both doc and docx

I hope this would solve your problem my friend. I have written it for docx to search and replace using apache.poi I recommend you to read complete Apache POI for more

public class Find_Replace_DOCX {

     public static void main(String args[]) throws IOException,
       InvalidFormatException,
       org.apache.poi.openxml4j.exceptions.InvalidFormatException {
      try {

       /**
        * if uploaded doc then use HWPF else if uploaded Docx file use
        * XWPFDocument
        */
       XWPFDocument doc = new XWPFDocument(
         OPCPackage.open("d:\\1\\rpt.docx"));
       for (XWPFParagraph p : doc.getParagraphs()) {
        List<XWPFRun> runs = p.getRuns();
        if (runs != null) {
         for (XWPFRun r : runs) {
          String text = r.getText(0);
          if (text != null && text.contains("$$key$$")) {
           text = text.replace("$$key$$", "ABCD");//your content
           r.setText(text, 0);
          }
         }
        }
       }

       for (XWPFTable tbl : doc.getTables()) {
        for (XWPFTableRow row : tbl.getRows()) {
         for (XWPFTableCell cell : row.getTableCells()) {
          for (XWPFParagraph p : cell.getParagraphs()) {
           for (XWPFRun r : p.getRuns()) {
            String text = r.getText(0);
            if (text != null && text.contains("$$key$$")) {
             text = text.replace("$$key$$", "abcd");
             r.setText(text, 0);
            }
           }
          }
         }
        }
       }

       doc.write(new FileOutputStream("d:\\1\\output.docx"));
      } finally {

      }

     }

    }

These document formats are complex objects that you almost certainly don't want to try to parse yourself. I would strongly suggest that you take a look at the apache poi libraries - these libraries have function to load and save doc and docx formats and means to access and modify the content of the files.

They are well documented, open source, currently maintained and freely available.

In Summary use these libraries to: a) load the file b) go through the content of the file programmatically and modify it as you need (i.e. do the search and replace) and c) save it back to disk.