How to parse XML and store it in a Map with SimpleXML?

Question

I'm having trouble parsing xml with simple xml framework. I want to store category id and list of tournaments inside a Map/hashMap how can I do that? I followed the tutorial on simple xml but it doesnt work for me.

I stored it in a list like this:

 @ElementList(entry = "Category", inline = true, required = false)
List<Category> category;

but now I wanna store it in a map.

Here is xml:

Tutorial that I followed:

Any help would be appreciated, tnx.

Answer 1

It's not possible by Annoations like @ElementList or @ElementMap, but using a Converter is still an (good) option.

Going that way means: Implementing a Converter for Tournaments which merges the Category-Id / Tournament List pair.

And here is how this is done:

---

First the necessary (data-) classes.

Tournament:

@Root(name = "Tournament")
public class Tournament
{
    @Text
    private String data;

    public Tournament(String data)
    {
        this.data = data;
    }

    private Tournament() { /* Required */ }

    // ...
}

Note: I gave the Tournament some data string, since the real data isn't shown. However, actually it doesn't matter what data it contains.

Category:

@Root(name = "Category")
public class Category
{
    private String id;

    // ...
}

Tournaments

@Root(name = "Tournaments")
@Convert(TournamentsConverter.class) // Specify the Converter used for this class
public class Tournaments
{
    private Map<String, List<Tournament>> tournaments;

    public Tournaments()
    {
        tournaments = new HashMap<>();
    }


    protected void put(String id, List<Tournament> tournaments)
    {
        this.tournaments.put(id, tournaments);
    }

    // ...
}

The @Convert will use the following Converter for serialization / deserialization of Tournaments. I haven't implemented the serialization part in this example (it's not difficult though).

Important: @Convert requires an AnnotationStrategy (see example below)!

Tournament Converter

public class TournamentsConverter implements Converter<Tournaments>
{
    private final Serializer serializer = new Persister();


    @Override
    public Tournaments read(InputNode node) throws Exception
    {
        Tournaments tournaments = new Tournaments();
        InputNode childNode = node.getNext();

        // Iterate over all childs of 'Tournaments'
        while( childNode != null )
        {
            if( childNode.getName().equals("Category") == true )
            {
                final String categoryId = childNode.getAttribute("category_id").getValue();

                List<Tournament> tournamentList = new ArrayList<>();
                InputNode child = childNode.getNext();

                // Iterate over all childs of 'Category'
                while( child != null )
                {
                    // Use a Serializer to read the nodes data
                    Tournament tournament = serializer.read(Tournament.class, child);
                    tournamentList.add(tournament);

                    child = childNode.getNext();
                }

                // Insert the Id / Tournament's pair
                tournaments.put(categoryId, tournamentList);
            }

            childNode = node.getNext();
        }

        return tournaments;
    }


    @Override
    public void write(OutputNode node, Tournaments value) throws Exception
    {
        // Implement as needed
        throw new UnsupportedOperationException("Not supported yet.");
    }

}

All the "magic" is done by the Converter:

1. Iterate over all of Tournaments child nodes
2. If it's a Category
   1. Get the id
   2. Iterate over all childs and add the Tournament's to a list
   3. Add the id / List of Tournament to the result Tournaments

As shown above, it's possible to use a Serializer for (de-)serialization of nodes. No need to implement that by hand.

Example

Finally, here's an example. Please note the AnnotationStrategy.

Serializer ser = new Persister(new AnnotationStrategy());

final String xml = "<Tournaments>\n"
        + "   <Category category_id=\"289\">\n"
        + "      <Tournament>aaaa</Tournament>\n"
        + "   </Category>\n"
        + "   <Category category_id=\"32\">\n"
        + "      <Tournament>bbbd</Tournament>\n"
        + "      <Tournament>cccc</Tournament>\n"
        + "   </Category>\n"
        + "</Tournaments>";

Tournaments t = ser.read(Tournaments.class, xml);

System.out.println(t);

Output:
_{Using generated toString() added to each class.}

Tournaments{tournaments={289=[Tournament{data=aaaa}], 32=[Tournament{data=bbbd}, Tournament{data=cccc}]}}

Answer 2

The problem is that you are trying to create a structure like Map<String, <List<Tournament>> and that doesn't seem to be possible with the ElementMap annotation. You need sort of an ElementMapList annotation. Maybe you can file an issue and Mr. Gallagher can add that.