conversation tree xml representation as java objects

Question

I have a question about the recommended way to map a conversation tree to java objects. I'm looking at something like the following:

<conversation>
    <npcAction id="1" text="Some action text" userChoice="2" />
    <userChoice id="2">
        <availableAction>3</availableAction>
        <availableAction>4</availableAction>
    </userChocie>
    <userAction id="3" text="Some more action text." npcChoice="5" />
    <userAction id="4" text="Different action text." npcChoice="5" />
    <npcChoice id="5">
        <availableAction>6</availableAction>
        <availableAction>7</availableAction>
    </npcChoice>
    <npcAction id="6" text="Still more action text." userChoice="8" />
    <npcAction id="7" text="Still more action text." userChoice="8" />
    <userChoice id="8" />
</conversation>

When I visualize how I want to interact with this programmatically, however, I feel like I want to make something like this:

public class UserAction {
    String text;
    NpcChoice npcChoice;
}
public class NpcAction {
    String text;
    UserChoice userChoice;
}
public class UserChoice {
    ArrayList<UserAction> actions;
}
public class NpcChoice {
    ArrayList<NpcAction> actions;
}

In implementation, NpcAction and UserAction have other specific values that differentiate them, but to keep it simple I trimmed them down.

My question is whether there is an easy way to bind these representations together. I could make some intermediate object representation of the xml data and then re-map it manually in Java, but I have this feeling that I'm missing something about the best way to represent this information. Any suggestions would be much appreciated!

Answer 1

You could do something like the following:

UserAction

public class UserAction {
    @XmlID 
    @XmlAttribute
    String id;

    @XmlAttribute String text;
    @XmlIDREF NpcChoice npcChoice;
}

NpcAction

public class NpcAction {
    @XmlID 
    @XmlAttribute
    String id;

    String text;
    UserChoice userChoice;
}

UserChoice

public class UserChoice {
    @XmlID 
    @XmlAttribute
    String id;

    @XmlElement(name="availableAction")
    ArrayList<UserAction> actions;
}

NpcChoice

public class NpcChoice {
    @XmlID 
    @XmlAttribute
    String id;

    @XmlElement(name="availableAction")
    ArrayList<NpcAction> actions;
}

For More Information

• http://blog.bdoughan.com/2010/10/jaxb-and-shared-references-xmlid-and.html