how to parse xml to hashmap?

Issue

I have an example of an xml I want to parse

 <?xml version="1.0" encoding="utf-8"?>

<Details>
    <detail-a>

        <detail> attribute 1 of detail a </detail>
        <detail> attribute 2 of detail a </detail>
        <detail> attribute 3 of detail a </detail>

    </detail-a>

    <detail-b>
        <detail> attribute 1 of detail b </detail>
        <detail> attribute 2 of detail b </detail>

    </detail-b>


</Details>

I would like from this xml to write a method that will parse it to hashmap that the key is a string and the value is a list of strings.

for instance : key "detail a" value={"attribute 1 of detail a","attribute 2 of detail a","attribute 3 of detail a"}

and so on..

what is the best way to do this ? because I got confused :\

I got this far to try to print detail-a and detail-b but I get blank...

public static void main(String[] args) {
    // TODO Auto-generated method stub

    DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();

        DocumentBuilder builder;
        try {
            builder = factory.newDocumentBuilder();
            File f= new File("src/Details.xml");
            Document doc=builder.parse(f);
            Element root=doc.getDocumentElement();
            NodeList children=root.getChildNodes();
            for(int i=0;i<children.getLength();i++)
            {
                Node child=children.item(i);
                if (child instanceof Element)
                {
                    Element childElement=(Element) child;
                    Text textNode=(Text)childElement.getFirstChild();
                    String text=textNode.getData().trim();
                    System.out.println(text);

                }
            }

        } catch (ParserConfigurationException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();   
        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

Solution

Use JAXB to read from xml and save it to a custom object.

Custom object class:

import java.util.List;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementWrapper;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlRootElement(name = "Details")
@XmlType(propOrder = { "detailA", "detailB" })
public class Details {
    private List<String> detailA;
    private List<String> detailB;

    public void setDetailA(List<String> detailA) {
        this.detailA = detailA;
    }

    @XmlElementWrapper(name = "detail-a")
    @XmlElement(name = "detail")
    public List<String> getDetailA() {
        return detailA;
    }

    public void setDetailB(List<String> detailB) {
        this.detailB = detailB;
    }

    @XmlElementWrapper(name = "detail-b")
    @XmlElement(name = "detail")
    public List<String> getDetailB() {
        return detailB;
    }
}

Extract the data from your xml into the object, then add contents to a map as desired:

public static void main(String[] args) throws JAXBException, FileNotFoundException {
    System.out.println("Output from our XML File: ");
    JAXBContext context = JAXBContext.newInstance(Details.class);
    Unmarshaller um = context.createUnmarshaller();
    Details details = (Details)um.unmarshal(new FileReader("details.xml"));
    List<String> detailA = details.getDetailA();
    List<String> detailB = details.getDetailB();

    Map<String, String[]> map = new HashMap<String, String[]>();
    map.put("detail-a", detailA.toArray(new String[detailA.size()]));
    map.put("detail-b", detailB.toArray(new String[detailB.size()]));


    for (Map.Entry<String, String[]> entry : map.entrySet()) {
        //key "detail a" value={"attribute 1 of detail a","attribute 2 of detail a","attribute 3 of detail a"}
        System.out.print("Key \"" +entry.getKey()+"\" value={");
        for(int i=0;i<entry.getValue().length;i++){
            if(i!=entry.getValue().length-1){
                System.out.print("\""+entry.getValue()[i]+"\",");
            }
            else{
                System.out.print("\""+entry.getValue()[i]+"\"}");
            }
        }
        System.out.println();
    }
}

Output will be:

Output from our XML File: 
Key "detail-a" value={"attribute 1 of detail a","attribute 2 of detail a","attribute 3 of detail a"}
Key "detail-b" value={"attribute 1 of detail b","attribute 2 of detail b"}

As a note: this will work only for the xml you provided as input in your question, if you need to add more details like detail-c and so on you must define them in your custom object as well.

XML used:

<?xml version="1.0" encoding="utf-8"?>
<Details>
    <detail-a>
        <detail>attribute 1 of detail a</detail>
        <detail>attribute 2 of detail a</detail>
        <detail>attribute 3 of detail a</detail>
    </detail-a>
    <detail-b>
        <detail>attribute 1 of detail b</detail>
        <detail>attribute 2 of detail b</detail>
    </detail-b>
</Details>

Answered By - MihaiC