Sample XML parsing

 package sample;  
   
 import org.w3c.dom.Document;  
 import org.w3c.dom.Element;  
 import org.w3c.dom.NodeList;  
 import org.xml.sax.InputSource;  
 import org.xml.sax.SAXException;  
   
 import javax.xml.parsers.DocumentBuilder;  
 import javax.xml.parsers.DocumentBuilderFactory;  
 import javax.xml.parsers.ParserConfigurationException;  
 import javax.xml.transform.TransformerException;  
   
 import com.sun.org.apache.xpath.internal.XPathAPI;  
   
 import java.io.FileNotFoundException;  
 import java.io.IOException;  
   
 public class XMLParser {  
   
   private static Element getRootElementFromXML() {  
     Element xmlRootElm = null;  
     try {  
       DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();  
       DocumentBuilder builder = factory.newDocumentBuilder();  
       InputSource is = new InputSource(XML_FILE_PATH);  
       Document doc = builder.parse(is);  
       xmlRootElm = doc.getDocumentElement();  
     } catch (FileNotFoundException e) {  
       System.out.println("FileNotFoundException :" + e);  
     } catch (IOException e) {  
       System.out.println("IOException :" + e);  
     } catch (SAXException e) {  
       System.out.println("SAXException :" + e);  
     } catch (ParserConfigurationException e) {  
       System.out.println("ParserConfigurationException :" + e);  
     }  
     return xmlRootElm;  
   }  
   
   private static Element getXmlElement(Element inRootElement, String inXpath) {  
     NodeList list = null;  
     Element element = null;  
     try {  
       list = XPathAPI.selectNodeList(inRootElement.getOwnerDocument(), inXpath);  
     } catch (TransformerException e) {  
       System.out.println("Unable to read XML : " + e);  
     }  
     if (list != null && list.getLength() > 0) {  
       element = (Element) list.item(0);  
     }  
     return element;  
   }  
   
   public static void main(String[] args) {  
     Element rootElement = getRootElementFromXML();  
     /**  
      * below constructed xpath : //country[@name='India']//city[@name='Chennai']  
      **/  
     String xPath = "//" + "country" + "[@name='" + "India" + "']//" + "city" +  
         "[@name='" + "Chennai" + "']";  
   
     Element element = getXmlElement(rootElement, xPath);  
     System.out.println("Code of Chennai : " + element.getAttribute("code"));  
   }  
   
   public static final String XML_FILE_PATH = "./src/sample/Sample.xml";  
 }  
   

Sample.xml

 <?xml version="1.0" encoding="UTF-8"?>  
 <countries>  
   <country name="India">  
     <city name="Delhi" code="011"/>  
     <city name="Mumbai" code="022"/>  
     <city name="Kolkata" code="033"/>  
     <city name="Chennai" code="044"/>  
   </country>  
   <country name="USA">  
     <city name="SanFrancisco" code="055"/>  
     <city name="Newyork" code="066"/>  
     <city name="Washington" code="077"/>  
     <city name="Florida" code="088"/>  
   </country>  
   <country name="Australia">  
     <city name="Sydney" code="099"/>  
     <city name="Melbourne" code="100"/>  
     <city name="Adelaide" code="111"/>  
     <city name="Perth" code="222"/>  
   </country>  
 </countries>  

Factory pattern

Factory Pattern - a type of Creational Pattern. The creational patterns deal with the best way to create instances of objects.

Sample design

 public interface IEquipment {
  String getType();
}

public abstract class Equipment implements IEquipment{
  public String getNumber() {
    return number;
  }
  protected void setNumber(String number) {
    this.number = number;
  }
  private String number;
}


public class Container extends Equipment{
  public Boolean getIsReefer() {
    return isReefer;
  }
  protected void setIsReefer(Boolean isReefer) {
    this.isReefer = isReefer;
  }
  public String getType() {
    return "Container";
  }

  private Boolean isReefer;
}


public class Chassis extends Equipment {
  public Boolean getIsWheeled() {
    return isWheeled;
  }
  protected void setWheeled(Boolean isWheeled) {
    this.isWheeled = isWheeled;
  }
  public String getType() {
    return "Chassis";
  }

  private Boolean isWheeled;
}


public class Accessory extends Equipment {
  public String getDescription() {
    return description;
  }
  protected void setDescription(String description) {
    this.description = description;
  }
  public String getType() {
    return "Accessory";
  }

  private String description;
}


// Factory producing Equipments
public class EquipmentFactory {
  public static IEquipment createEquipment(String inEquipmentType) {
    IEquipment equipment = null;
    if (CONTAINER.equals(inEquipmentType)) {
      equipment = new Container();
    } else if (CHASSIS.equals(inEquipmentType)) {
      equipment = new Chassis();
    } else if (ACCESSORY.equals(inEquipmentType)) {
      equipment = new Accessory();
    }
    return equipment;
  }

  private static final String CONTAINER = Container.class.getName();
  private static final String CHASSIS = Chassis.class.getName();
  private static final String ACCESSORY = Accessory.class.getName();
}