从XML文件java程序中删除节点

Question

When I try to remove a node from XML node from java program it is giving me a strange problem. It is removing alternate nodes. I have to remove existing nodes before inserting new nodes. my xml file is:

<?xml version="1.0" encoding="windows-1252" ?>
<chart>
<categories>
 <category label="3 seconds"/>
 <category label="6 seconds"/>
 <category label="9 seconds"/>
 <category label="12 seconds"/>
</categories>

</chart>

my java program is:

      DocumentBuilderFactory  docFactory  = DocumentBuilderFactory.newInstance();
      DocumentBuilder docBuilder = docFactory.newDocumentBuilder();

      Document doc = docBuilder.parse(filePath);


      Node categories = doc.getElementsByTagName("categories").item(0);

      NodeList categorieslist = categories.getChildNodes();

      // if exists delete old data the insert new data.


      for (int c = 0; c < categorieslist.getLength(); c++) {

        Node node = categorieslist.item(c);
        categories.removeChild(node);
      }
    for(int i=1;i<20;i++){

    Element category = doc.createElement("category");
    category.setAttribute("label",3*i+" seconds");
    categories.appendChild(category);
  }

This code is deleting alternative nodes I don't know why. The resulting XML is showing like this:

<categories>
 <category label="6 seconds"/>
 <category label="12 seconds"/>
 <category label="3 seconds"/>
 <category label="6 seconds"/>
 <category label="9 seconds"/>
      .....
      .....
 </categories>

Answer 1

Every time you remove a child the list becomes shorter, the list isn't a static collections, so every time you call getLength() you get the actual size

Node categories = doc.getElementsByTagName("categories").item(0);
NodeList categorieslist = categories.getChildNodes();
while (categorieslist.getLength() > 0) {
    Node node = categorieslist.item(0);
    node.getParentNode().removeChild(node);
}