How to set the text content of a node in XML in java?

Consider the example,

<PARAMETER FIELD="QUERYSTORE_TYPE" LABEL="Query Type" NAME="QUERYSTORE" NUM_ROW="40">
      <DEFAULT>""</DEFAULT>
    </PARAMETER>

    <PARAMETER FIELD="GUESS_SCHEMA" LABEL="Guess Schema" NAME="GUESS_SCHEMA" NUM_ROW="40">
      <DEFAULT></DEFAULT>
    </PARAMETER>

    <PARAMETER FIELD="MEMO_SQL" LABEL="Query" NAME="QUERY" NUM_ROW="45" REQUIRED="true">
      <DEFAULT>"select id, name from employee"</DEFAULT>
    </PARAMETER>

now I have to remove all double quotes in content of DEFAULT tag. I tried doing the following

NodeList nList = doc.getElementsByTagName("PARAMETER");

for (int temp = 0; temp < nList.getLength(); temp++) {

    Node nNode = nList.item(temp);

    if (nNode.getNodeType() == Node.ELEMENT_NODE) {
        Element eElement = (Element) nNode;
        NodeList nl = nNode.getChildNodes();
        for(int k = 0; k<nl.getLength(); k++)
        {
            if(nl.item(k).getNodeName().equals("DEFAULT"))
            {
                nl.item(k).setTextContent(nl.item(k).getTextContent().replaceAll("\"", ""));
            }
        }
 }

}

But its not working. When I open the XML file it still contains those double quotes. How do i do this? And also wherever there is double quote, I have to add another attribute to PARAMETER element namely encode with value indicating if there was a double quote in DEFAULT tag. ie

<PARAMETER FIELD="QUERYSTORE_TYPE" LABEL="Query Type" NAME="QUERYSTORE" NUM_ROW="40" encode ="true">
          <DEFAULT></DEFAULT>
        </PARAMETER>

        <PARAMETER FIELD="GUESS_SCHEMA" LABEL="Guess Schema" NAME="GUESS_SCHEMA" NUM_ROW="40" encode = "false">
          <DEFAULT></DEFAULT>
        </PARAMETER>

        <PARAMETER FIELD="MEMO_SQL" LABEL="Query" NAME="QUERY" NUM_ROW="45" REQUIRED="true" encode="true">
          <DEFAULT>"select id, name from employee"</DEFAULT>
        </PARAMETER>

How do I do this?