java - 有谁知道如何向 org.w3c.dom.Element 添加值以实例化 MiningSchema 和 SupportVectorMachineModel ？

Question

我有一个 github 存储库 here里面有我所有的代码。给我一个空指针的代码片段位于模型中，空指针位于模型:32。我仍然不完全确定在这里做什么。我已经准备好其他一切，可以工作了，这是给我带来问题的一件事。代码片段如下:

 private SupportVectorMachine svm = new SupportVectorMachine();
 private SupportVectors supportVectors = new SupportVectors();
 private SupportVectorMachineModel svmModel;
 private MiningSchema schema;
 private ClassLoader loader = new ClassLoader();

 private Element element;

public  void create(Instances instances) throws IOException, SAXException
{
    assert instances!=null;
        DocumentBuilder builder = null;
        element = (Element) builder.parse(instances.toString());
        try
        {
            schema = new MiningSchema(element, instances, schema.getTransformationDictionary());
            svmModel = new SupportVectorMachineModel(element, instances, schema);
        } catch (Exception e)
        {
            e.printStackTrace();
        }
    }

Answer 1

 private Element element;
 Document doc;

 public  void create(Instances instances) throws IOException, SAXException, ParserConfigurationException {
     assert instances!=null;
     DocumentBuilderFactory documentBuilderFactory = new DocumentBuilderFactoryImpl();
     DocumentBuilder builder = documentBuilderFactory.newDocumentBuilder();
     assert builder != null;
     doc = builder.parse(instances.toString());
         element = (Element) doc;    

我从实例创建了一个新文档，然后将其转换为一个元素。