How to edit a node's value of an existing XML file from a SD card and save it back?

Question

I want to edit a node's value of an existing XML file from the SD card.

For example if I want to edit RouteName's value from Mountain Trip to Sea Trip.

<Trip> 
   <RouteID>12345</RouteID>
   <RouteName>Mountain Trip</RouteName>
</Trip>

I try to use the following code but it doesn't effect to the XML file on the SD card.

try {
    DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
    Document doc = docBuilder.parse(
        new File(Environment.getExternalStorageDirectory()+"/Trip/"+tripID+".trip"));

    Node nodes = doc.getElementsByTagName("RouteName").item(0);
    // newname is String variable which retrives value from edittext
    nodes.setNodeValue(newname);

    TransformerFactory factory = TransformerFactory.newInstance();
    Transformer transformer = factory.newTransformer();

    DOMSource source = new DOMSource(doc);
    StreamResult result = new StreamResult(
        new File(Environment.getExternalStorageDirectory()+"/Trip/"+tripID+".trip"));
    transformer.transform(source, result);
} catch (Exception e) {
    e.printStackTrace();
}

Why doesn't the XML file on the SD card get updated?

Answer 1

I finally got the answer from here, thanks ProfSmiles.

The fix was a change from nodes.setNodeValue to nodes.setTextContent.

try {
    String filePath = Environment.getExternalStorageDirectory()+"/Trip/"+tripID+".trip";  
    File file = new File(filePath);
    DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
    Document doc = docBuilder.parse(file);

    // Change the content of node
    Node nodes = doc.getElementsByTagName("RouteName").item(0);
    // I changed the below line form nodes.setNodeValue to nodes.setTextContent
    nodes.setTextContent(newname);

    Transformer transformer = TransformerFactory.newInstance().newTransformer();
    transformer.setOutputProperty(OutputKeys.INDENT, "yes");

    // initialize StreamResult with File object to save to file
    StreamResult result = new StreamResult(file);
    DOMSource source = new DOMSource(doc);
    transformer.transform(source, result);

} catch (Exception e) {
    e.printStackTrace();
}