Update or Edit XML File using DOM Parser

Update or Edit XML File using DOM Parser

DOM and SAX Parser  

In our earlier tutorial we have seen how to read XML file using DOM and SAX Parser. In this tutorial we will see how to edit or update XMl file using DOM parser. We have used below sample XML to update using DOM parser.

SAMPLE XML:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?> 
<organization>
 <employee mode="permanent">
  <name>John</name>
  <empid>1234</empid>
  <designation>SE</designation>
  <technology>Java</technology>
 </employee>
 <employee mode="contract">
  <name>David</name>
  <empid>4545</empid>
  <designation>Manager</designation>
  <technology>.NET</technology>
 </employee>
</organization>

XML AFTER UPDATE: 

<?xml version="1.0" encoding="UTF-8" standalone="no" ?> 
<organization>
 <employee mode="permanent">
  <name>John</name> 
  <empid>1234</empid> 
  <designation>SE</designation> 
  <age>35</age> 
 </employee>
 <employee mode="permanent">
  <name>David</name> 
  <empid>4545</empid> 
  <designation>Senior Manager</designation> 
  <age>35</age> 
 </employee>
 <employee mode="permanent">
  <name>Steve</name> 
  <empid>5635</empid> 
  <designation>Lab Engineer</designation> 
  <age>38</age> 
 </employee>
</organization>

If we seen above XML we have modified such as

• Deleting <technology> node from the XML
• Updating attribute value from "contract" to "permanent" for 2nd employee
• Updating <designation> node value from "Manager" to "Senior Manager"
• Adding new <employee> element

Below example java code will be used to modify the XML as per given above. 

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

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

public class EditXML {
 
 public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException, TransformerException {
  editMyXML("D:\\document.xml");
 }
 
 public static void editMyXML(String file) throws ParserConfigurationException, SAXException, IOException, TransformerException{
  
  DocumentBuilderFactory builderFac = DocumentBuilderFactory.newInstance();
  DocumentBuilder builder = builderFac.newDocumentBuilder();
     Document doc = builder.parse(new File(file));

     System.out.println ("ROOT: " + doc.getDocumentElement().getNodeName());
        NodeList list = doc.getElementsByTagName("employee");
        System.out.println("No. Of Employees: " + list.getLength());
                
        for(int i= 0; i<list.getLength(); i++){
            Node node = list.item(i);
            if(node.getNodeType() == Node.ELEMENT_NODE) {
                Element element = (Element)node;
                String mode, name, empid, designation, technology;
                                
                mode = element.getAttribute("mode");
                
                NodeList nListName = element.getElementsByTagName("name");
                Element nElementName = (Element)nListName.item(0);
                NodeList tListName = nElementName.getChildNodes();
                name =((Node)tListName.item(0)).getNodeValue().trim();
                
                NodeList nListEmpId = element.getElementsByTagName("empid");
                Element nElementEmpId = (Element)nListEmpId.item(0);
                NodeList tListEmpId = nElementEmpId.getChildNodes();
                empid = ((Node)tListEmpId.item(0)).getNodeValue().trim();
                
                NodeList nListDesi = element.getElementsByTagName("designation");
                Element nElementDesi = (Element)nListDesi.item(0);
                NodeList tListDesi = nElementDesi.getChildNodes();
                designation = ((Node)tListDesi.item(0)).getNodeValue().trim();
                
                NodeList nListTech = element.getElementsByTagName("technology");
                Element nElementTech = (Element)nListTech.item(0);
                NodeList tListTech = nElementTech.getChildNodes();
                technology =((Node)tListTech.item(0)).getNodeValue().trim();
                
                // Updating only for 4545 (David) Employee
                if(empid.equals("4545")){
                 
                 // Updating MODE from "contract" to "Permanent"
                 node.getAttributes().getNamedItem("mode").setTextContent("permanent");
                 
                 // Updating Designation from "Manager" to "Senior Manager"
                 ((Node)tListDesi.item(0)).setTextContent("Senior Manager");
                }
                
                // Adding new Node called "age"
                Element nElementAge = doc.createElement("age");
                nElementAge.appendChild(doc.createTextNode("35"));
                element.appendChild(nElementAge);
                
                // Deleting "technology" Node
                element.removeChild(nElementTech);
            }
        }
        
        //Adding new employee
        addNewEmployee(doc, "permanent", "Steve", "5635", "Lab Engineer", "38");
        
        
        // Writing update XML file
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
  Transformer transformer = transformerFactory.newTransformer();
  DOMSource source = new DOMSource(doc);
  StreamResult result = new StreamResult(new File("D:\\document.xml"));
  transformer.transform(source, result);
 }
 
 public static void addNewEmployee(Document doc, String mode, String name, String empId, String designation, String age){
  
  Element root = doc.getDocumentElement();
        
        Element element = doc.createElement("employee");
        root.appendChild(element);
        
  Attr attr = doc.createAttribute("mode");
  attr.setValue("permanent");
  element.setAttributeNode(attr);
  
  Element nElementName = doc.createElement("name");
        nElementName.appendChild(doc.createTextNode("Steve"));
        element.appendChild(nElementName);
        
        Element nElementEmpId = doc.createElement("empid");
        nElementEmpId.appendChild(doc.createTextNode("5635"));
        element.appendChild(nElementEmpId);
        
        Element nElementDesi = doc.createElement("designation");
        nElementDesi.appendChild(doc.createTextNode("Lab Engineer"));
        element.appendChild(nElementDesi);
  
  Element nElementAge = doc.createElement("age");
        nElementAge.appendChild(doc.createTextNode("38"));
        element.appendChild(nElementAge);
  } 
}

Java Interview Questions - 4

Java Interview Questions - 4

Interview Questions  

In this tutorial we will see about few simple interview programming questions.

1. Sort 3 numbers without IF condition or looping.

public class Sort3No {
 public static void main(String[] args) {
  int x = 9;
  int y = 3;
  int z = 7;

  int first = Math.min(x, Math.min(y, z));
  int third = Math.max(x, Math.max(y, z));
  int second = x + y + z - first - third;

  System.out.println("SORTED NO's : " + first + ", " + second + ", "+ third);
 }
}

OUTPUT:

SORTED NO's : 3, 7, 9

2. Reverse the number without using String

public class ReverseNumber {
 
 public static void main(String[] args) {
  
  int number = 123456;

  int revNo = 0;
  while(number > 0){
   revNo = (10 * revNo) + (number % 10);
   number = number / 10;
  }
  
  System.out.println("REVERSED NO : "+revNo);
 }
}

OUTPUT:

REVERSED NO : 654321

3. Print first N Fibonacci numbers.

public class Fibonacci {

  public static void main(String[] args) { 
       int input = 10;
       int fib = 0,  val= 1;
       System.out.print("First "+input+" Fibonacci Numbers : ");
       for (int i = 0; i < input; i++) {
          fib = fib + val;
          val = fib - val;
          System.out.print(fib+", "); 
       }
  }
}

OUTPUT:

First 10 Fibonacci Numbers : 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 

4. Convert String to Date Object 

public class StringToDate {
 
 public static void main(String args[]) {
  try{
         String strDate = "23-5-2013";

         SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy");
         Date date = format.parse(strDate);
         System.out.println("DATE : "+date);
  }catch (ParseException e) {
   e.printStackTrace();
  }
    }
}

OUTPUT:

DATE : Thu May 23 00:00:00 IST 2013

5. Find entered date is valid or not

public class ValidDate {

 public static void main(String[] args) {

  int day = 29;
  int month = 2;
  int year = 1984;

  int[] leapYearDays = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
  int[] nonLeapYearDays = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

  if (month >= 1 && month <= 12) {
   if (year % 4 == 0) {
    if (day >= 1 && day <= leapYearDays[month - 1]) {
     System.out.println("Valid Date...");
    } else {
     System.out.println("Invalid Date");
    }
   } else {
    if (day >= 1 && day <= nonLeapYearDays[month - 1]) {
     System.out.println("Valid Date...");
    } else {
     System.out.println("Invalid Date");
    }
   }
  } else {
   System.out.println("Invalid Date");
  }
 }
}

OUTPUT:

Valid Date...

6. Find the day of week by given date.

public class DayOfWeek {

 public static void main(String[] args) {

  int day = 23;
  int month = 5;
  int year = 2013;

  String days[] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };

  int a = year - (14 - month) / 12;
  int x = a + a / 4 - a / 100 + a / 400;
  int b = month + 12 * ((14 - month) / 12) - 2;
  int c = (day + x + (31 * b) / 12) % 7;

  System.out.println(days[c]);
 }
}

OUTPUT:

Thursday

7. Print 5 random numbers between 2 numbers

public class PrintRandom {
 
 public static void main(String[] args) {
  
  int min = 100;
  int max = 200;
  
  for(int i=0;i<5;i++){
   int rand = new Random().nextInt(max);
   if(rand > min){
    System.out.println(rand);
   }else{
    i--;
   }
  }
 }
}

OUTPUT:

122
180
193
114
187

8. Replace character in a string without using Java API functions

public class ReplaceChar {

 public static void main(String[] args) {
  String str = "This document is the API specification for version 6 of the Java";
  System.out.println("INPUT              : "+str);
  str = replaceChar(str, 'Q', 'i'); // Change all 'i' to 'Q' 
  System.out.println("AFTER CHAR REPLACE : "+str);
 }
 
 public static String replaceChar(String str, char newChar, char oldChar){
  try{
   char[] charAry = str.toCharArray();
   for(int i=0;i<str.length();i++){
    if(charAry[i] == oldChar){
     charAry[i] = newChar;
    }
   }
   str = new String(charAry);
  }catch (Exception e) {
   e.printStackTrace();
  }
  return str;
 }
}

OUTPUT:

INPUT               : This document is the API specification for version 6 of the Java
AFTER CHAR REP: ThQs document Qs the API specQfQcatQon for versQon 6 of the Java

9. Write a Java program to find given number is odd or even without / or % operators. 

public class OddOrEven {
 
 public static void main(String[] args) {
  int no = 25;
  while(no>2){
   no -= 2;
  }
  if(no == 1){
   System.out.println("Given no. is Odd Number...");
  }else{
   System.out.println("Given no. is Even Number...");
  }
 }
}

OUTPUT:

Given no. is Odd Number...

10.  This is a simple mathematical calculation program. 
    
Example: Raj purchased the bag for Rs.2750 which includes 10% tax of bag price. So what will be the price of bag and tax amount?. Program should work for whatever be the amount as input.

public class CalculatePrice {
 
 public static void main(String[] args) {
  int price = 2750;
  float bagPrice = ((price/11f)*10f);
  float taxAmt = (price/11f);
  System.out.println("BAG PRICE   : "+bagPrice);
  System.out.println("TAX AMOUNT  : "+taxAmt);
  System.out.println("TOTAL PRICE : "+(bagPrice+taxAmt));
 }
}

OUTPUT:

BAG PRICE   : 2500.0
TAX AMOUNT  : 250.0
TOTAL PRICE : 2750.0

Create ZIP File using Java Code

Create ZIP File using Java Code

ZIP  

We seen how to unzip a ZIP file using Java code in our earlier tutorial, now we will see how to create a ZIP file using Java code in this tutorial. Below sample code will read list of files in a folder and zip file name as input parameters. 

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class CreateZIPFile {

 public static void main(String argv[]) {
  // List of files in a folder to zip
  String filesPath = "D:\\filesfolder";
  // ZIP file name and path to create
  String zipFileName = "D:\\myZipFile.zip";
  
  createZIPFile(filesPath, zipFileName);
 }
 
 public static void createZIPFile(String filesPath, String zipFileName){

  try {
  
   FileOutputStream dest = new FileOutputStream(zipFileName);
   ZipOutputStream out = new ZipOutputStream(new BufferedOutputStream(dest));

   byte buffer[] = new byte[1024];
   File file = new File(filesPath);
   String files[] = file.list();
   System.out.println("No. of files to ZIP : "+files.length);
   BufferedInputStream bis = null;
   for (int i = 0; i < files.length; i++) {
    FileInputStream fi = new FileInputStream(filesPath+ "\\"+ files[i]);
    bis = new BufferedInputStream(fi, 1024);
    ZipEntry entry = new ZipEntry(files[i]);
    out.putNextEntry(entry);
    int count;
    while ((count = bis.read(buffer, 0, 1024)) != -1) {
     out.write(buffer, 0, count);
    }
    bis.close();
   }
   out.close();
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}

Unzip a ZIP File using Java Code

Unzip a ZIP File using Java Code

ZIP  

In this tutorial we will see about unzipping a Zip file using Java code. Below example will gives you the code to unzip a zip file by taking zip file and output folder path as input parameters. 

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
import java.util.Enumeration;

public class UnZip {

 public static final void main(String[] args) {

  // Zip file path
  String zipFile = "D:\\myZipFile.zip";

  // Output folder to save the unzip files
  String outputFolder = "D:\\unzipfolder\\";
  

  unzipFile(zipFile, outputFolder);

 }
 
 public static void unzipFile(String zipFile, String outputFolder){
  
  ZipFile zFile = null;

  try {
   zFile = new ZipFile(zipFile);
   Enumeration zEntries = zFile.entries();

   while (zEntries.hasMoreElements()) {
    ZipEntry zipEntry = (ZipEntry) zEntries.nextElement();

    // Check for Directory or not
    if (zipEntry.isDirectory()) {
     // Creating directory
     (new File(zipEntry.getName())).mkdir();
     continue;
    }

    // Unzipping files
    createUnzipFile(zFile.getInputStream(zipEntry),
      new BufferedOutputStream(new FileOutputStream(
        outputFolder + zipEntry.getName())));
   }
   zFile.close();
  } catch (IOException e) {
   e.printStackTrace();
  
  } 
 }

 public static final void createUnzipFile(InputStream iStream,
   OutputStream oStream) {
  try {
   byte[] buffer = new byte[1024];
   int len;
   while ((len = iStream.read(buffer)) >= 0)
    oStream.write(buffer, 0, len);

  iStream.close();
  oStream.close();
  } catch (Exception e) {
   e.printStackTrace();
 
  } 
 }
}