While using XStream to read XML to object, what if I don't know how many fields the XML will have?

Question

I've set up a system to read from XML but I need to build the object manually before reading XML to it.

XML:

<actor id="" PGFVersion="" GSCVersion="">
  <attributes>
    <text id="name">Actor 1</text>
    <real id="time">0</real>
    <point id="position">
      <real id="x">0</real>
      <real id="y">0</real>
    </point>
    <size id="size">
      <real id="width">0</real>
      <real id="height">0</real>
    </size>
    <angle id="rotation">0</angle>
    <color id="color">
      <real id="red">0</real>
      <real id="green">0</real>
      <real id="blue">0</real>
      <real id="alpha">0</real>
    </color>
    <image id="image">0</image>
    <text id="tags">tag1  tag2</text>
    <boolean id="preloadArt">true</boolean>
  </attributes>
</actor>

How I set-up the object:

public class Attributes {

    @XStreamImplicit
     public List fields = new ArrayList();

  public Attributes(){

      this.addText("name", "Actor 1");
      this.addReal("time", "0");
      this.addPoint("position", "0", "0");
      this.addSize("0", "0");
      this.addAngle("rotation", "0");
      this.addColor("0", "0", "0", "0");
      this.addImage("0");
      this.addText("tags", "tag1  tag2");
      this.addBoolean("preloadArt","true");


  }

  public void addText(String id, String value){
      Text text = new Text(id,value);
      this.fields.add(text);
  }

  //other adders

}

But what should I do with random count of fields. What if there are 2 <color> fields on the XML I'll read. How to automate this?

Answer 1

Usually the XStream object have fields representing the fields in the XML. See the Person-object in the XStream tutorial.

If you have this type of object, I think you should be able to annotate the color property with @XStreamImplicit to handle multiple occurences in the XML.

Somewhere along the lines of this untested code:

public class Attributes {

    // 'name' and 'text' occurs only once.
    public String name;

    public String text;

    public Size size;

    // The other attributes

    // color can occur multiple times.
    @XStreamImplicit
    public int color;

}