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Java Parsing xml document from url

When parsing an URL, I got this error:
[Fatal Error] :1:1: Content is not allowed in prolog
What should be improved in the code?
There is also required link.
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
public class Main2 {
public static void main(String[] args) throws ParserConfigurationException, MalformedURLException {
String link = "https://samples.openweathermap.org/data/2.5/weather?q=London&appid=b6907d289e10d714a6e88b30761fae22";
URL url = new URL(link);
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder;
Document doc;
try {
builder = factory.newDocumentBuilder();
doc = builder.parse(url.openStream());
} catch (ParserConfigurationException | SAXException | IOException ex) {
ex.printStackTrace();
}
}
}

Please could you check the exact response type is coming for URL you provided , as I see the Json response type in browser as well as in postman even if i am sending content type as "application/xml". So dont parse the response using xml parser as your response is coming in JSON format. You need to use json parser for parsing Json object.

Parse String to XML Document jdom2

I have a problem. I want to convert the string to a xml document.
But this code is throw exception:
Exception in thread "main" java.lang.ClassCastException: com.sun.org.apache.xerces.internal.dom.DeferredDocumentImpl cannot be cast to org.jdom2.Document
at ru.unicus.osp.Test.main(Test.java:17)
import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.jdom2.Document;
import org.xml.sax.InputSource;
public class Test {
public static void main(String[] args) throws Exception {
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader("<root><node1></node1></root>"));
Document doc = (Document) db.parse(is);
}
}
Got any ideas?

You mixed two libraries here. The simplest thing that can be done is to change the import from:
import org.jdom2.Document;
to
import org.w3c.dom.Document;
So the code should look like:
import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
public class Test {
public static void main(String[] args) throws Exception {
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader("<root><node1></node1></root>"));
Document doc = (Document) db.parse(is);
}
}

You are mixing two libraries here, DOM, and JDOM.
your current output Document is a JDOM document, it seems, but you are trying to cast a w3 DOM Document instance to be one, and you are failing.
If you want to have a JDOM Document as your output, then your code should likely be:
SAXBuilder builder = new SAXBuilder();
Document doc = builder.build(new StringReader("<root><node1></node1></root>"));
For a DOM document output, just use a DOM Document (org.w3c.dom.Document) instead of org.jdom2.Document

org.xml.sax.SAXParseException: Premature end file

I currently have the following XML file.
http://www.cse.unsw.edu.au/~cs9321/14s1/assignments/musicDb.xml
My XMLParser.java class.
package edu.unsw.comp9321.assignment1;
import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
public class XMLParser {
public void search () {
try{
File fXmlFile = new File("/COMP9321Assignment1/xml/musicDb.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);
System.out.println("Root element :" + doc.getDocumentElement().getNodeName());
} catch (Exception e) {
e.printStackTrace();
}
}
}
I create an object in another class and call the search but I keep receiving the above stated error.
Would anyone know what the problem might be?
Thanks for your help.

Normally "org.xml.sax.SAXParseException: Premature end file" occurrs due to several reasons
1.Check your xml were all the tags are closed properly at same level
2.check if any name space issues.
3.check for welformness of your xml document

Reading XML online and Storing It (Using Java)

I found and followed an example from Stackoverflow (http://stackoverflow.com/questions/2310139/how-to-read-xml-response-from-a-url-in-java) of how to read an XML file from a URL (as you can see in my code pasted below). My only trouble is that now that I got the program to read the XML, how do I get it to store it? For example, could I make it save the information to a XML file built into the project (this would be the best solution for me, if it's possible)? Such as, take for example, I have a blank XML file built into the project. The program runs, reads the XML code off of the URL, and stores it all into the pre-built blank XML file. Could I do this?
If I sound confusing or un-clear about anything, just ask me to clarify what I'm looking for.
And here is my code, if you'd like to look at what I have so far:
package xml.parsing.example;
import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
public class XmlParser {
public static void main (String[] args) throws IOException, ParserConfigurationException, SAXException, TransformerException {
URL url = new URL("http://totheriver.com/learn/xml/code/employees.xml");
URLConnection conn = url.openConnection();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(conn.getInputStream());
TransformerFactory tfactory = TransformerFactory.newInstance();
Transformer xform = tfactory.newTransformer();
// that’s the default xform; use a stylesheet to get a real one
xform.transform(new DOMSource(doc), new StreamResult(System.out));
}
}

Very simply:
File myOutput = new File("c:\\myDirectory\\myOutput.xml");
xform.transform(new DOMSource(doc), new StreamResult(myOutput));

This page has some great examples of how to serialize the DOM object to a neatly formatted XML file.

Creating an XML document using namespaces in Java

I am looking for example Java code that can construct an XML document that uses namespaces. I cannot seem to find anything using my normal favourite tool so was hoping someone may be able to help me out.

There are a number of ways of doing this. Just a couple of examples:
Using XOM
import nu.xom.Document;
import nu.xom.Element;
public class XomTest {
public static void main(String[] args) {
XomTest xomTest = new XomTest();
xomTest.testXmlDocumentWithNamespaces();
}
private void testXmlDocumentWithNamespaces() {
Element root = new Element("my:example", "urn:example.namespace");
Document document = new Document(root);
Element element = new Element("element", "http://another.namespace");
root.appendChild(element);
System.out.print(document.toXML());
}
}
Using Java Implementation of W3C DOM
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.ls.DOMImplementationLS;
import org.w3c.dom.ls.LSOutput;
import org.w3c.dom.ls.LSSerializer;
public class DomTest {
private static DocumentBuilderFactory dbf = DocumentBuilderFactory
.newInstance();
public static void main(String[] args) throws Exception {
DomTest domTest = new DomTest();
domTest.testXmlDocumentWithNamespaces();
}
public void testXmlDocumentWithNamespaces() throws Exception {
DocumentBuilder db = dbf.newDocumentBuilder();
DOMImplementation domImpl = db.getDOMImplementation();
Document document = buildExampleDocumentWithNamespaces(domImpl);
serialize(domImpl, document);
}
private Document buildExampleDocumentWithNamespaces(
DOMImplementation domImpl) {
Document document = domImpl.createDocument("urn:example.namespace",
"my:example", null);
Element element = document.createElementNS("http://another.namespace",
"element");
document.getDocumentElement().appendChild(element);
return document;
}
private void serialize(DOMImplementation domImpl, Document document) {
DOMImplementationLS ls = (DOMImplementationLS) domImpl;
LSSerializer lss = ls.createLSSerializer();
LSOutput lso = ls.createLSOutput();
lso.setByteStream(System.out);
lss.write(document, lso);
}
}

I am not sure, what you trying to do, but I use jdom for most of my xml-issues and it supports namespaces (of course).
The code:
Document doc = new Document();
Namespace sNS = Namespace.getNamespace("someNS", "someNamespace");
Element element = new Element("SomeElement", sNS);
element.setAttribute("someKey", "someValue", Namespace.getNamespace("someONS", "someOtherNamespace"));
Element element2 = new Element("SomeElement", Namespace.getNamespace("someNS", "someNamespace"));
element2.setAttribute("someKey", "someValue", sNS);
element.addContent(element2);
doc.addContent(element);
produces the following xml:
<?xml version="1.0" encoding="UTF-8"?>
<someNS:SomeElement xmlns:someNS="someNamespace" xmlns:someONS="someOtherNamespace" someONS:someKey="someValue">
<someNS:SomeElement someNS:someKey="someValue" />
</someNS:SomeElement>
Which should contain everything you need. Hope that helps.