Question

For example,I want to generate the following xml file by using java with DOM

 <catalogue>
    <books>
        <book id="1">
           <name>Gone with the wind</name>
            <quantity>2</quantity>
        </book>
        <book id="2">
           <name>Call of the wind</name>
           <quantity>3</quantity>
         </book>
         <book id="3">
           <quality>Good</quality>
          </book>
    </books>
    </catalogue>

It’s not very difficult to produce xml file with only 1 node named book, but with more than 1 with the same name, I dont know how to do it? I got the error:

Duplicate local variable

This is one part of my java code:
I tried to create the first book element with the code:

  Element book = doc.createElement("book");
  rootElement.appendChild(book);

  Element name = doc.createElement("name");
  name.appendChild(doc.createTextNode("Gone with the wind"));
  book.appendChild(name);

And then I used the same code to create the second and the third book element, and I found the error.
Is there any other way to do it?
Can anyone give me a suggestion please?
Thank you very much for your time

Answer 1

I’m guessing you are appending the same object twice. You need to call createElement each time.

This won’t work

    Element name = doc.createElement("name");
    name.appendChild(doc.createTextNode("Gone with the wind"));
    book.appendChild(name);

    name.appendChild(doc.createTextNode("Call of the wind"));
    book.appendChild(name);

You need to do

    Element name = doc.createElement("name");
    name.appendChild(doc.createTextNode("Gone with the wind"));
    book.appendChild(name);

    name = doc.createElement("name");
    name.appendChild(doc.createTextNode("Call of the wind"));
    book.appendChild(name);

Complete example

     Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();

    Element root = doc.createElement("catalogue");
    doc.appendChild(root);

    Element books = doc.createElement("books");
    root.appendChild(books);

    Element book1 = doc.createElement("book");
    book1.setAttribute("id", "1");
    books.appendChild(book1);

    Element book1_name = doc.createElement("name");
    book1_name.setTextContent("Gone with the wind");
    book1.appendChild(book1_name);

    Element book1_quantity = doc.createElement("quantity");
    book1_quantity.setTextContent("2");
    book1.appendChild(book1_quantity);

    Element book2 = doc.createElement("book");
    book2.setAttribute("id", "2");
    books.appendChild(book2);

    Element book2_name = doc.createElement("name");
    book2_name.setTextContent("Call of the wind");
    book2.appendChild(book2_name);

    Element book2_quantity = doc.createElement("quantity");
    book2_quantity.setTextContent("3");
    book2.appendChild(book2_quantity);

    Element book3 = doc.createElement("book");
    book3.setAttribute("id", "3");
    books.appendChild(book3);

    Element book3_quality = doc.createElement("quality");
    book3_quality.setTextContent("Good");
    book3.appendChild(book3_quality);