I have a xml file that looks like this.
<Device>
<Staff>
<Name>ABC</Name>
<Name>Hello</Name>
</Staff>
<Connect>
<Speed>123</Speed>
<Speed>456</Speed>
</Connect>
</Device>
I need help in retrieving the value of name & speed as i have never tried xml before. I am getting null pointer exception whenever I try to retrieve the element values. Any help is appreciated.
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
// Load the input XML document, parse it and return an instance of the
// Document class.
Document document = builder.parse(new File("C:/Users/AA/Desktop/eclipse/lol/testing.xml"));//change to own directory
NodeList nodeList = document.getDocumentElement().getChildNodes();
System.out.println(nodeList.getLength());
for (int i = 0; i < nodeList.getLength(); i++) {
Node node = nodeList.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE) {
System.out.println(i);
Element elem = (Element) node;
// Get the value of the ID attribute.
// String ID = node.getAttributes().getNamedItem("ID").getNodeValue();
// Get the value of all sub-elements.
String name = elem.getElementsByTagName("Name")
.item(0).getChildNodes().item(0).getNodeValue();
Integer speed = Integer.parseInt(elem.getElementsByTagName("Connect")
.item(0).getChildNodes().item(0).getNodeValue());//null pointer exception happens here
staffList.add(new staff(name));
connectList.add(new connect(speed));
}
}
// Print all employees.
for (staff stl : staffList)
{System.out.println("STAFF "+stl.getName());}
for (connect ctl : connectList)
{System.out.println("Connect "+ctl.getSpeed());}
You will have null pointer exceptions because you're assuming that in every iteration of the for loop, the desired nodes have children elements:
String name = elem.getElementsByTagName("Name")
.item(0).getChildNodes().item(0).getNodeValue();
In the above code, you are accessing the first child of a Name element which is a text node (e.g. ABC), and then getting its children nodes, which will cause an exception since there no children elements inside the text node.
Likewise,
Integer speed = Integer.parseInt(elem.getElementsByTagName("Connect")
.item(0).getChildNodes().item(0).getNodeValue());
will cause an exception in one of the iterations of the loop where elem corresponds to Connect itself.
You can try the following code instead:
if (node.getNodeType() == Node.ELEMENT_NODE) {
System.out.println(i);
Element elem = (Element) node;
// Get the value of the ID attribute.
// String ID =
// node.getAttributes().getNamedItem("ID").getNodeValue();
// Get the value of all sub-elements.
NodeList nameNodes = elem.getElementsByTagName("Name");
for(int j = 0; j < nameNodes.getLength(); j++) {
Node nameNode = nameNodes.item(j);
staffList.add(new staff(nameNode.getTextContent()));
}
NodeList speedNodes = elem.getElementsByTagName("Speed");
for(int j = 0; j < speedNodes.getLength(); j++) {
Node speedNode = speedNodes.item(j);
connectList.add(new connect(Integer.parseInt(speedNode.getTextContent())));
}
}
P.S.: Try to use class names that start with an uppercase.
You want getTextContent() rather than getNodeValue() - the latter always returns null for element nodes.
See: DOMDocument getNodeValue() returns null (contains an output escaped string)
Related
I have to extract tag value from an xml Document that contains a single tag like below:
<error>Permission denied</error>
i have tried:
String xmlRecords = "<error>Permission denied</error>"
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(xmlRecords));
Document doc = db.parse(is);
Node nodes = doc.getFirstChild();
String = nodes.getNodeValue();
but it dont works.
How can i do it ?
Use doc.getDocumentElement().getTextContent() to get the string Permission denied.
With DOM it´s util to know the structure of the XML document, and which node level are you looking for.
After get Document, you can use document.getElementsByTagName("root") to look for the root or father tags, and get the childs as a list to look for the item. Something like this:
NodeList listresults = document.getElementsByTagName('father/root element string');
NodeList nl = listresults.item(0).getChildNodes();
// Recorremos los nodos
for (int temp = 0; temp < nl.getLength(); temp++) {
Node node = nl.item(temp);
// Check if it is a node
if (node.getNodeType() == Node.ELEMENT_NODE) {
Element element = (Element) node;
if(element.getNodeName().equals("error")){
// check the element
}
}
}
I hope this helps you.
just try following code.
String value = nodes.getTextContent();
You have to construct the string if you are using the above approach. You will get the string values of the tag name and content using the functions.
Tag name = nodes.getTextContent()
tag value = nodes.getLocalName()
I guess this is what you want
Element element = document.getDocumentElement();
NodeList errorTagList = element.getElementsByTagName("error");
if (errorTagList != null && errorTagList.getLength() > 0) {
NodeList errorTagSubList = errorTagList.item(0).getChildNodes();
if (errorTagSubList != null && errorTagSubList.getLength() > 0) {
String value = errorTagSubList.item(0).getNodeValue();
}
}
How do I list the element names at a given level in an xml schema hierarchy? The code I have below is listing all element names at every level of the hierarchy, with no concept of nesting.
Here is my xml file:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?><?xml-stylesheet type="text/xsl" href="CDA.xsl"?>
<SomeDocument xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:something">
<title>some title</title>
<languageCode code="en-US"/>
<versionNumber value="1"/>
<recordTarget>
<someRole>
<id extension="998991"/>
<addr use="HP">
<streetAddressLine>1357 Amber Drive</streetAddressLine>
<city>Beaverton</city>
<state>OR</state>
<postalCode>97867</postalCode>
<country>US</country>
</addr>
<telecom value="tel:(816)276-6909" use="HP"/>
</someRole>
</recordTarget>
</SomeDocument>
Here is my java method for importing and iterating the xml file:
public static void parseFile() {
//get the factory
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
try {
//Using factory get an instance of document builder
DocumentBuilder db = dbf.newDocumentBuilder();
//parse using builder to get DOM representation of the XML file
Document dom = db.parse("D:\\mypath\\somefile.xml");
//get the root element
Element docEle = dom.getDocumentElement();
//get a nodelist of elements
NodeList nl = docEle.getElementsByTagName("*");
if (nl != null && nl.getLength() > 0) {
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE) {
System.out.println("node.getNodeName() is: "+node.getNodeName());
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
The output of the above program is:
title
languageCode
versionNumber
recordTarget
someRole
id
addr
streetAddressLine
city
state
postalCode
country
telecom
Instead, I would like to output the following:
title
languageCode
versionNumber
recordTarget
It would be nice to then be able to list the children of recordTarget as someRole, and then to list the children of someRole as id, addr, and telecom. And so on, but at my discretion in the code. How can I change my code to get the output that I want?
You're getting all nodes with this line:
NodeList nl = docEle.getElementsByTagName("*");
Change it to
NodeList nl = docEle.getChildNodes();
to get all of its children. Your print statement will then give you the output you're looking for.
Then, when you iterate through your NodeList, you can choose to call the same method on each Node you create:
NodeList children = node.getChildNodes();
If you want to print an XML-like structure, perhaps a recursive method that prints all child nodes is what you are looking for.
You could re-write the parseFile (I'd rather call it parseChildrenElementNames) method to take an input String that specifies the element name for which you want to print out its children element names:
public static void parseChildrenElementNames(String parentElementName) {
// get the factory
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
try {
// Using factory get an instance of document builder
DocumentBuilder db = dbf.newDocumentBuilder();
// parse using builder to get DOM representation of the XML file
Document dom = db
.parse("D:\\mypath\\somefile.xml");
// get the root element
NodeList elementsByTagName = dom.getElementsByTagName(parentElementName);
if(elementsByTagName != null) {
Node parentElement = elementsByTagName.item(0);
// get a nodelist of elements
NodeList nl = parentElement.getChildNodes();
if (nl != null) {
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE) {
System.out.println("node.getNodeName() is: "
+ node.getNodeName());
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
However, this will only consider the first element that matches the specified name.
For example, to get the list of elements under the first node named someRole, you would call parseChildrenElementNames("someRole"); which would print out:
node.getNodeName() is: id
node.getNodeName() is: addr
node.getNodeName() is: telecom
I have a function I would like to loop through the xml and pull out certain tags.
My xml looks like this:
<Report_Data>
<Report_Entry>
<Company>Test</Company>
<Name>Test Name</Name>
<Division>Test Division</Division>
</Report_Entry>
<Report_Entry>
<Company>Test 2</Company>
<Name>Test Name 2</Name>
<Division>Test Division 2</Division>
</Report_Entry>
<Report_Entry>
<Company>Test 3</Company>
<Name>Test Name 3</Name>
<Division>Test Division 3</Division>
</Report_Entry>
</Report_Data>
Here is my code to loop through:
String comp, name, div, nodeName, NodeValue;
Node node;
try
{
XPathFactory xpathFactory = XPathFactory.newInstance();
XPath xpath = xpathFactory.newXPath();
InputSource source = new InputSource(new StringReader(coaFULL));
Document doc2 = (Document) xpath.evaluate("/", source, XPathConstants.NODE);
NodeList nodeList = (NodeList) xpath.compile("/Report_Data/Report_Entry").evaluate(doc2, XPathConstants.NODESET);
System.out.println("NODE LIST LENGTH =" + nodeList.getLength());
String nodeName, nodeValue = "";
Node node;
for(int i = 0; i < nodeList.getLength(); i++)
{
node = nodeList.item(i);
node = nodeList.item(i).getFirstChild();
nodeName = node.getNodeName();
nodeValue = node.getChildNodes().item( 0 ).getNodeValue();
if(nodeName.equals("Company"))
{
comp = nodeValue;
}
else if( nodeName.equals("Name"))
{
name = nodeValue;
}
else if(nodeName.equals("Division"))
{
div = nodeValue;
}
System.out.println("COMPANY = " + comp);
System.out.println("NAME = " + name);
System.out.println("DIVISION = " + div);
}
When I run my code, only the first value (company) gets an actual value, everything else is blank. I also tried adding node = nodeList.item(i).getNextSibling(); inside of each if statement to grab the next node, but that did not work.
My nodeList does have items in it, over 1000. Is there a problem with this statement: NodeList nodeList = (NodeList) xpath.compile("/Report_Data/Report_Entry").evaluate(doc2, XPathConstants.NODESET);?
Should it be: NodeList nodeList = (NodeList) xpath.compile("/Report_Data/Report_Entry/*").evaluate(doc2, XPathConstants.NODESET);
I tried it with the /* at the end but that caused the nodeList to have every single node in it. I want to make sure that when I grab a Report_Entry node, that I set the string variables to the correct values that correspond to each other.
==========================================================
Solution: It's ugly but my solution was to just go with one loop and use the second list of children nodes with hard coded values:
for(int i = 0; i < nodeList.getLength(); i++)
{
node = nodeList.item(i);
tempList = node.getChildNodes();
System.out.println("TEMP LIST LENGTH =" + tempList.getLength());
comp = tempList.item(0).getTextContent();
name = tempList.item(1).getTextContent();
div = tempList.item(2).getTextContent();
}
Thanks to #hage for his help.
Maybe it's because your node is only the first child?
node = nodeList.item(i);
node = nodeList.item(i).getFirstChild();
I guess nodeList.item(i) will give you the Report_Entrys and their first child is the Company.
You will need to loop over all children of the Company entry
EDIT (regarding your edit):
tempList.item(x) is the Company, Name, and then Division. When you get the first child of this one, you are at the text node (the actual content). And because you try to get the name of this node, you get the #text output (see this).
To get name and value of the nodes, try this (untested)
nodeName = tempList.item(x).getNodeName();
nodeValue = tempList.item(x).getTextContent();
I have a XML file that looks like this:
<exist:result xmlns:exist="http://exist.sourceforge.net/NS/exist">
<exist:collection name="/db/RCM" created="2013-03-24T09:37:34.957+05:30" owner="admin" group="dba" permissions="rwxrwxrwx">
<exist:resource name="demo2.xml" created="2013-03-24T09:44:13.696+05:30" last-modified="2013-03-24T09:44:13.696+05:30" owner="guest" group="guest" permissions="rw-r--r--"/>
<exist:resource name="demo3.xml" created="2013-03-24T09:45:47.592+05:30" last-modified="2013-03-24T09:45:47.592+05:30" owner="guest" group="guest" permissions="rw-r--r--"/>
<exist:resource name="rcmdemo.xml" created="2013-03-25T11:36:45.659+05:30" last-modified="2013-03-25T11:36:45.659+05:30" owner="guest" group="guest" permissions="rw-r--r--"/>
<exist:resource name="rcmdemo2.xml" created="2013-03-25T11:47:03.564+05:30" last-modified="2013-03-25T11:47:03.564+05:30" owner="guest" group="guest" permissions="rw-r--r--"/>
</exist:collection>
</exist:result>
I want to fetch the name of the XML files, so the output looks like this:
demo2.xml
demo3.xml
rcmdemo.xml
rcmdemo2.xml
I have written the following code:
NodeList nodeList = doc.getElementsByTagName("exist:resource");
for (int i = 0; i < nodeList.getLength(); i++) {
Node n = nodeList.item(i);
Node actualNode = n.getFirstChild();
if (actualNode != null) {
System.out.println(actualNode.getNodeValue());
}
}
But it does not return the output that I want, where am I going wrong?
In this example name is an attribute of the node rather than the name of the node. Please look at the following question for information regarding attributes of nodes, the second answer in particular is what you are looking for i think.
get the the attributes from an XML File using Java
You have to get the attribute from the given node since your name is an attribute of exist:resource.
NodeList nodeList = doc.getElementsByTagName("exist:resource");
for (int i = 0; i < nodeList.getLength(); i++) {
Node n = nodeList.item(i);
Node actualNode = n.getFirstChild();
if (actualNode != null) {
// Will return node value
System.out.println(actualNode.getNodeValue());
// Will return the attribute value
System.out.println(current.getAttributeValue("name"));
}
}
I want to read a multi level tags from xml(DOM) using java and the sample xml is : <root>
<subclass>
<subclass>
<subclass>
<name>test1</name>
<address>address1</address>
</subclass>
<name>test2</name>
<address>address2</address>
</subclass>
<name>test3</name>
<address>address3</address>
</subclass>
</root>
How to read <name>test2</name> and <address>address2</address> from the above xml?
I have given a sample code .. but i need to find the values dynamically.
when i am iterating bu using subclass tag, it's giving all the data. just i want to know how to get the specific data like <name>test2</name> and <address>address2</address> .
Below is my java code which is reading the above xml:
NodeList fList = firstWordElement
.getElementsByTagName("root");
for (int i = 0; i < fList.getLength(); i++) {
Node firstFLNode = fList.item(i);
if (firstFLNode.getNodeType() == Node.ELEMENT_NODE) {
Element firstWdElement = (Element) firstFLNode;
NodeList firstWdList = firstWdElement.getElementsByTagName("innerclass");
for (int j = 0; j < firstWdList.getLength(); j++) {
Element firstWd1Element = (Element) firstWdList.item(j);
if (firstWd1Element.getNodeType() == Node.ELEMENT_NODE) {
String InnerName = ParseUtil.getTagValue("name", firstWd1Element);
String InnerFormat = ParseUtil.getTagValue("format", firstWd1Element);
String InnerDescription = ParseUtil.getTagValue("description", firstWd1Element);
NodeList innerClassList = firstWd1Element.getElementsByTagName("subclass");
for (int k = 0; k < innerClassList.getLength(); k++) {
Element subClassElement = (Element) innerClassList
.item(k);
if (subClassElement.getNodeType() == Node.ELEMENT_NODE) {
String InnerSubName = ParseUtil.getTagValue("name", subClassElement);
System.out.println("Innername==="+ InnerSubName);
String InnerSubFormat = ParseUtil.getTagValue("format", subClassElement);
System.out.println("Innerformat==="+ InnerSubFormat);
String InnerSubDescription = ParseUtil.getTagValue("description", subClassElement);
System.out.println("Innerdescription==="+ InnerSubDescription);
}
}
}
}
}
}
A quick way to do this is by using XPath queries. Check out these tutorials:
http://www.ibm.com/developerworks/library/x-javaxpathapi/index.html
http://www.javabeat.net/2009/03/how-to-query-xml-using-xpath/
Traditionally you have to iterate trough the nodes, usually done by creating a NodeList with getChildren() from the parent node. If you only want the test2 -node you have to perform some sort of comparison - you can't jump straight to the second node. That is to say you can, but that wont make a very robust or scale able solution.