Develop Reference

How do i fix Document: null error on GML-Response

I have to convert a GML-Server Response to a GPX-File with jdom in Java
So far the Get-Feature-Request i send to the server is correct and gives me a GML-File as response, but when i want to print the file it says [#document: null]
The output on console:
url https://www.geoportal-amt-beetzsee.de/isk/beet_radwanderwege?service=WFS&version=1.0.0&REQUEST=GetFeature&typename=Riewend-Burgwall-Wanderweg
[#document: null]
try {
//zu Funktionstestzwecken - löschen wenn nicht mehr benötigt
String typename = gui.ConverterDialog.tfconverter.getText();
String urlString = gui.UrlDialog.txturlinput.getText() + "?service=WFS&version=1.0.0&REQUEST=GetFeature&typename=" + typename;
//entfernen wenn nicht mehr benötigt
System.out.println("url "+ urlString);
URL url = new URL(urlString);
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(url.openStream());
//doc.getDocumentElement().normalize();
//entfernen wenn nicht mehr benötigt
//doc null ???
System.out.println(doc);
} catch(Exception e) {
String errorMessage = "An error occured:" + e;
System.err.println(errorMessage);
e.printStackTrace();
}

When the line
System.out.println(doc);
runs, it calls the toString() method of the document doc and prints out that. The toString() method of the document doesn't serialize the XML document to a string; instead it just prints the node name and its value. The name of the document node is #document, and document nodes don't have values, so null gets printed instead.
I tried running your XML parsing code on a test XML document and it also printed out [#document: null].
It might look like your XML parsing has failed and left you with an empty document, but I don't believe that to be the case. Your code is quite probably working correctly.
If you want to serialize an XML document to a string, see this question.

This Code solved the issue:
//...
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(url.openStream());
doc.getDocumentElement().normalize();
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
StreamResult result = new StreamResult(new StringWriter());
DOMSource source = new DOMSource(doc);
transformer.transform(source, result);
String xmlString = result.getWriter().toString();
System.out.println(xmlString);

How to append new nodes to an existing xml file

Hello Im new in useing xml and now trying to append new nodes for existing xml file.
This is my code to write a xml
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBulder = docFactory.newDocumentBuilder();
//root mainElement
Document doc = docBulder.newDocument();
Element rootElement = doc.createElement("Books");
doc.appendChild(rootElement);
//root Book
Element Book = doc.createElement("Book");
rootElement.appendChild(Book);
//setting ganre for a book
Attr att = doc.createAttribute("ganre");
att.setValue(ganre);
Book.setAttributeNode(att);
//book id
Element bookId = doc.createElement("bookId");
bookId.appendChild(doc.createTextNode(randomString(4)));
Book.appendChild(bookId);
//bookname element
Element bookname = doc.createElement("bookName");
bookname.appendChild(doc.createTextNode(name));
Book.appendChild(bookname);
//book author
Element bookAuthor = doc.createElement("bookAuthor");
bookAuthor.appendChild(doc.createTextNode(author));
Book.appendChild(bookAuthor);
//book year
Element bookYear = doc.createElement("bookYear");
bookYear.appendChild(doc.createTextNode(String.valueOf(year)));
Book.appendChild(bookYear);
//book available
Element bookAvail = doc.createElement("bookAvailable");
bookAvail.appendChild(doc.createTextNode(String.valueOf(free)));
Book.appendChild(bookAvail);
//write in a XMLFile
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File("Test/Books.xml"));
transformer.transform(source, result);
System.out.println("File saved!");
this is how I trying to append new nodes
File fXmlFile = new File("Test/Books.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);
Node books = doc.getFirstChild();
Element newBook = doc.createElement("Book");
[here the troubles comes]
what i want to do is rewrite file like this:
<Books>
<Book ganre="fantasy">
<bookId>7111</bookId>
<bookName>Tron</bookName>
<bookAuthor>Brawm</bookAuthor>
<bookYear>15</bookYear>
<bookAvailable>true</bookAvailable>
</Book>
<Book ganre="action">
<bookId>312</bookId>
<bookName>Corn</bookName>
<bookAuthor>Down</bookAuthor>
<bookYear>23</bookYear>
<bookAvailable>false</bookAvailable>
</Book>
</Books>
but every time Im can only rewrite or damage the xml file.
ps Im getting all my bookName's and so on from the input

I can just suggest to use the JDom library. Its very easy to use and implement, always worked for me.
JDOM is, quite simply, a Java representation of an XML document. JDOM provides a way to represent that document for easy and efficient reading, manipulation, and writing. It has a straightforward API, is a lightweight and fast, and is optimized for the Java programmer. It’s an alternative to DOM and SAX, although it integrates well with both DOM and SAX.
There are some good tutorials at mykong.com explaining how to read, modify and create xml-files :
http://www.mkyong.com/java/how-to-modify-xml-file-in-java-jdom/

problem was solved. My solution is:
File fXmlFile = new File("Test/Books.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);
// doc.getDocumentElement().normalize();
Element nList = doc.getDocumentElement();
System.out.println("-----------------------");
//root a new book
Element newBook = doc.createElement("Book");
//setting ganre for a book
Attr att = doc.createAttribute("ganre");
att.setValue(ganre);
newBook.setAttributeNode(att);
//book id
Element bookId = doc.createElement("bookId");
bookId.appendChild(doc.createTextNode(randomString(4)));
newBook.appendChild(bookId);
//bookname element
Element bookname = doc.createElement("bookName");
bookname.appendChild(doc.createTextNode(name));
newBook.appendChild(bookname);
//book author
Element bookAuthor = doc.createElement("bookAuthor");
bookAuthor.appendChild(doc.createTextNode(author));
newBook.appendChild(bookAuthor);
//book year
Element bookYear = doc.createElement("bookYear");
bookYear.appendChild(doc.createTextNode(String.valueOf(year)));
newBook.appendChild(bookYear);
//book available
Element bookAvail = doc.createElement("bookAvailable");
bookAvail.appendChild(doc.createTextNode(String.valueOf(free)));
newBook.appendChild(bookAvail);
nList.appendChild(newBook);
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
//initialize StreamResult with File object to save to file
StreamResult result = new StreamResult(new File("Test/Books.xml"));
DOMSource source = new DOMSource(doc);
transformer.transform(source, result);
System.out.println("DONE");

Modifying an XML in Java

I have an XML document which has null values in its Value tag (something similar to below)
<ns2:Attribute Name="Store" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri">
<ns2:AttributeValue/>
</ns2:Attribute>
Now, I have to write Java code to modify the values as below.
<ns2:Attribute Name="Store" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:uri">
<ns2:AttributeValue>ABCDEF</ns2:AttributeValue>
</ns2:Attribute>
I am using DOM parser to parse the XML. I am able to delete the null tag for " but not able to add new values. I am not even sure if we have a direct way to replace or add the values.
Below is the code I am using to remove the child("")
Node aNode = nodeList.item(i);
eElement = (Element) aNode;
eElement.removeChild(eElement.getFirstChild().getNextSibling());
Thanks in advance

Just add data through setTextContent to the element. Sample code is as below:
public static void main(String[] args) throws IOException, SAXException, ParserConfigurationException, TransformerException {
String xml = "<ns2:Attribute Name=\"Store\" NameFormat=\"urn:oasis:names:tc:SAML:2.0:attrname-format:uri\"><ns2:AttributeValue/></ns2:Attribute>";
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(new ByteArrayInputStream(xml.getBytes()));
doc.getDocumentElement().normalize();
NodeList nList = doc.getElementsByTagName("ns2:AttributeValue");
for (int i=0;i<nList.getLength();i++) {
Element elem = (Element)nList.item(i);
elem.setTextContent("Content"+i);
}
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(System.out);
transformer.transform(source, result);
System.out.println(nList.getLength());
}

Getting value of child node from XML in java

My xml file looks like this
<InNetworkCostSharing>
<FamilyAnnualDeductibleAmount>
<Amount>6000</Amount>
</FamilyAnnualDeductibleAmount>
<IndividualAnnualDeductibleAmount>
<NotApplicable>Not Applicable</NotApplicable>
</IndividualAnnualDeductibleAmount>
<PCPCopayAmount>
<CoveredAmount>0</CoveredAmount>
</PCPCopayAmount>
<CoinsuranceRate>
<CoveredPercent>0</CoveredPercent>
</CoinsuranceRate>
<FamilyAnnualOOPLimitAmount>
<Amount>6000</Amount>
</FamilyAnnualOOPLimitAmount>
<IndividualAnnualOOPLimitAmount>
<NotApplicable>Not Applicable</NotApplicable>
</IndividualAnnualOOPLimitAmount>
</InNetworkCostSharing>
I am trying to get Amount value from <FamilyAnnualDeductibleAmount> and also from <FamilyAnnualOOPLimitAmount>. How do i get those values in java?

You may use two XPath queries /InNetworkCostSharing/FamilyAnnualDeductibleAmount and InNetworkCostSharing/FamilyAnnualOOPLimitAmount or just get the node InNetworkCostSharing and retrieve the values of its two direct children.
Solution using XPath:
// load the XML as String into a DOM Document object
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
ByteArrayInputStream bis = new ByteArrayInputStream("YOUR XML".getBytes());
Document doc = docBuilder.parse(bis);
// XPath to retrieve the content of the <FamilyAnnualDeductibleAmount> tag
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xpath.compile("/InNetworkCostSharing/FamilyAnnualDeductibleAmount/text()");
String familyAnnualDeductibleAmount = (String)expr.evaluate(doc, XPathConstants.STRING);

StAX based solution:
XMLInputFactory f = XMLInputFactory.newInstance();
XMLStreamReader rdr = f.createXMLStreamReader(new FileReader("test.xml"));
while (rdr.hasNext()) {
if (rdr.next() == XMLStreamConstants.START_ELEMENT) {
if (rdr.getLocalName().equals("FamilyAnnualDeductibleAmount")) {
rdr.nextTag();
int familyAnnualDeductibleAmount = Integer.parseInt(rdr.getElementText());
System.out.println("familyAnnualDeductibleAmount = " + familyAnnualDeductibleAmount);
} else if (rdr.getLocalName().equals("FamilyAnnualOOPLimitAmount")) {
rdr.nextTag();
int familyAnnualOOPLimitAmount = Integer.parseInt(rdr.getElementText());
System.out.println("FamilyAnnualOOPLimitAmount = " + familyAnnualOOPLimitAmount);
}
}
}
rdr.close();
Note that StAX is especially good for cases like yours, it skips all unnecessary elements reading only the ones you need

Try something like this(use getElementsByTagName to get the parent nodes and then get the value be reaching out to child node):
File xmlFile = new File("NetworkCost.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(xmlFile );
doc.getDocumentElement().normalize();
NodeList nList = doc.getElementsByTagName("FamilyAnnualDeductibleAmount");
String familyDedAmount = nList.item(0).getChildNodes().item(0).getTextContent();
nList = doc.getElementsByTagName("FamilyAnnualOOPLimitAmount");
String familyAnnualAmount =
nList.item(0).getChildNodes().item(0).getTextContent();

I think I found the solution with this question from stackoverflow
Getting XML Node text value with Java DOM

How to convert String to DOM Document object in java?

I have a case like getting an XML and convert the XML elements to document object and getting the element values and attributes which i have been created already
Here is the piece of code i have tried to convert the string to DOM document object
String xmlString = " <r><e>d</e></r>";
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
org.w3c.dom.Document document = builder.parse(new InputSource(new StringReader(xmlString)));
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(document);
StreamResult result = new StreamResult(new StringWriter());
transformer.transform(source, result);
String str1 = result.getWriter().toString();
System.out.println(str1);
But this case is valid for only elements without attributes
what can we do if the
String xmlString = "<element attribname="value" attribname1="value1"> pcdata</element>"
we are using Double quotes for the attribute values"value". The compiler is showing error
Suggest me if there any xml encoder and decoder is there to handle this scenarios ??

you can try
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader("<root><node1></node1></root>"));
Document doc = db.parse(is);
refer this http://www.java2s.com/Code/Java/XML/ParseanXMLstringUsingDOMandaStringReader.htm

Either escape the double quotes with \
String xmlString = "<element attribname=\"value\" attribname1=\"value1\"> pcdata</element>"
or use single quotes instead
String xmlString = "<element attribname='value' attribname1='value1'> pcdata</element>"

DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document document = db.parse(new ByteArrayInputStream(xmlString.getBytes("UTF-8"))); //remove the parameter UTF-8 if you don't want to specify the Encoding type.
this works well for me even though the XML structure is complex.
And please make sure your xmlString is valid for XML, notice the escape character should be added "\" at the front.
The main problem might not come from the attributes.

public static void main(String[] args) {
final String xmlStr = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>\n"+
"<Emp id=\"1\"><name>Pankaj</name><age>25</age>\n"+
"<role>Developer</role><gen>Male</gen></Emp>";
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder;
try
{
builder = factory.newDocumentBuilder();
Document doc = builder.parse( new InputSource( new StringReader( xmlStr )) );
} catch (Exception e) {
e.printStackTrace();
}
}