JSON/XML PARSING IN JAVA

In this tutorial we are going to see how to parse xml and json files. first we will just parse a xml file and later we will parse xml elements to objects

1) for java we are using DOM parser

xml file to be parsed


<?xml version="1.0"?>
<company>
<employee id="1001">
<firstname>yong</firstname>
<lastname>mna</lastname>
<nickname>mrreferenc</nickname>
<salary>100000</salary>
</employee>
<employee id="2001">
<firstname>dev</firstname>
<lastname>journal</lastname>
<nickname>general</nickname>
<salary>200000</salary>
</employee>
       <employee id="2002">
<firstname>darth</firstname>
<lastname>vader</lastname>
<nickname>anakan</nickname>
<salary>2000</salary>
</employee>
<employee id="2003">
<firstname>obi</firstname>
<lastname>van kanobi</lastname>
<nickname>ben kanobi</nickname>
<salary>1500</salary>
</employee>
<employee id="2009">
<firstname>hello</firstname>
<lastname>world</lastname>
<nickname>wasteland</nickname>
<salary>20</salary>
</employee>
</company>


and the coe to parse the nodes and attributes were


package xmlparsing;

import java.io.File;
import java.io.IOException;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class Domparsing {

public static void main(String[] args) throws SAXException, IOException, ParserConfigurationException {
File file= new File("/home/solomon/solo.xml");
System.out.println(file.exists());
Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(file);
       NodeList companylist= doc.getElementsByTagName("employee");
       for(int i=0;i<companylist.getLength();i++){
      Node companynoes=companylist.item(i);
      System.out.println(companynoes.getTextContent());
   if(companynoes.hasAttributes()){
  NamedNodeMap attributes = companynoes.getAttributes();
  for(int j=0;j<attributes.getLength();j++){
  System.out.println("attribut values"+attributes.getNamedItem("id").getNodeValue());
  }
   }
   
   
       }
}

}

and the output is

true

yong
mna
mrreferenc
100000

attribut values1001

dev
journal
general
200000

attribut values2001

darth
vader
anakan
2000

attribut values2002

obi
van kanobi
ben kanobi
1500

attribut values2003

hello
world
wasteland
20

attribut values2009

XPATH;
  now we use get the firstname of all employees whose salary is greater than 1500

1)create an xpath object
      XPath xpath= XPathFactory.newInstance().newXPath();

private static void getdata(Document doc, XPath path){
List<String>salarybyname= new ArrayList<>();
try {
XPathExpression expression = path.compile("/company/employee[salary>"+1500+"]/firstname/text()");
NodeList nodelist=(NodeList)expression.evaluate(doc, XPathConstants.NODESET);
System.out.println(nodelist.getLength());
for(int i=0;i<nodelist.getLength();i++){
System.out.println(nodelist.item(i).getTextContent());
}
System.out.println("Number of items added to the list"+salarybyname.size());
for(String employee:salarybyname){
System.out.println(employee);
}

} catch (XPathExpressionException e) {
e.printStackTrace();
e.printStackTrace();
}

}

and the o/p is

yong
dev
darth