SAX解析器返回null

Question

我正在尝试解析在线XML文档，但是当我运行以下代码时，它会在get()方法中返回NULL异常。我尝试进一步调试以实现输入流可能返回空值。谁知道什么是错的？

public class XMLHelper extends DefaultHandler{

private String URL_MAIN = "https://www.ura.gov.sg/LsmMap/xml/lsm-test.xml";

String TAG = "XMLHelper";
Boolean currTag = false;
String currTagVal = "";

private PostValue post ;

private ArrayList<PostValue> postsList = new ArrayList<PostValue>();


//to read the XML
public void get() {
    try {
        SAXParserFactory factory = SAXParserFactory.newInstance();
        SAXParser mSaxParser = factory.newSAXParser();
        XMLReader mXmlReader = mSaxParser.getXMLReader();

        mXmlReader.setContentHandler(this);

        InputStream mInputStream = new URL(URL_MAIN).openStream();
        mXmlReader.parse(new InputSource(mInputStream));

    } catch (Exception e) {
        Log.e(TAG, "Exception123: " + e.getMessage());

    }
}

}