XSTest.java:

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;

import com.thoughtworks.xstream.XStream;

public class XSTest {
	private static final String XML_FILE = "c:\\temp\\items.xml";
	private XStream xs;
	
	public XStream getXS()
	{
		if(xs == null)
		{
			xs = new XStream();
			xs.processAnnotations(Store.class);
			xs.processAnnotations(Item.class);
			xs.processAnnotations(Weapon.class);
			xs.processAnnotations(Armor.class);
		}
		
		return xs;
	}
	
	public void createModel()
	{
		Store s = new Store();
		s.items.add(new Weapon(1, "Short sword", "data/items/shortsword.png", "swords", "data/sprites/swordattack.png"));
		s.items.add(new Weapon(2, "Bastard sword", "data/items/bastardsword.png", "swords", "data/sprites/swordattack.png"));
		s.items.add(new Weapon(3, "Long sword", "data/items/longsword.png", "swords", "data/sprites/swordattack.png"));
		s.items.add(new Armor(4, "Studded leather armor", "data/items/studdedleather.png", "Chest", 20));
		
		save(s, XML_FILE);
	}
	
	public Store loadStore()
	{
		XStream xs = getXS();
		return (Store) xs.fromXML(new File(XML_FILE));
	}
	
	public boolean save(Object obj, String location)
	{
		try
		{
			File f = new File(location);
			File dir = f.getParentFile();
			if(!dir.exists())
				dir.mkdirs();
			XStream xs = getXS();
			String xml = xs.toXML(obj);
			FileWriter fstream = new FileWriter(f);
			BufferedWriter out = new BufferedWriter(fstream);
			out.write(xml);
			out.close();
			System.out.println(String.format("Generated xml '%s':\n%s", location, xml));
			return true;
		}
		catch(Exception ex)
		{
			return false;
		}
	}
	
	public static void main(String[] args)
	{
		XSTest test = new XSTest();
		test.createModel();
		Store s = test.loadStore();
		
		for(Item i : s.items)
		{
			System.out.println(i.toString());
		}
	}
}

Store.java:

import java.util.ArrayList;

import com.thoughtworks.xstream.annotations.XStreamAlias;

@XStreamAlias("store")
public class Store {
	
	public ArrayList<Item> items;
	
	public Store()
	{
		items = new ArrayList<Item>();
	}
}

Item.java:

import com.thoughtworks.xstream.annotations.XStreamAlias;

@XStreamAlias("item")
public abstract class Item {
	public int id;
	public String name;
	public String inventorySheet;
	
	public Item()
	{
		
	}
	public Item(int id, String name, String inventorySheet)
	{
		this.id = id;
		this.name = name;
		this.inventorySheet = inventorySheet;
	}
	
	public abstract String getTypeName();

	@Override 
	public String toString()
	{
		return String.format("%s (%d): %s", getTypeName(), id, name);
	}
}

Armor.java:


import com.thoughtworks.xstream.annotations.XStreamAlias;

@XStreamAlias("armor")
public class Armor extends Item{
	public String armorType;
	public int armorValue;
	
	public Armor()
	{
		
	}
	public Armor(int id, String name, String sheet, String type, int value)
	{
		super(id, name, sheet);
		this.armorType = type;
		this.armorValue = value;
	}
	@Override
	public String getTypeName() {
		return "Armor";
	}
	
	@Override
	public String toString()
	{
		return String.format("%s, type: %s, armor value: %d", super.toString(), armorType, armorValue);
	}
}

Weapon.java:


import com.thoughtworks.xstream.annotations.XStreamAlias;

@XStreamAlias("weapon")
public class Weapon extends Item{
	public String weaponType;
	public String attackSheet;
	
	public Weapon(){}
	public Weapon(int id, String name, String inventorySheet, String type, String attackSheet )
	{
		super(id, name, inventorySheet);
		this.weaponType = type;
		this.attackSheet = attackSheet;
	}
	@Override
	public String getTypeName() {
		return "Weapon";
	}
	
	@Override
	public String toString()
	{
		return String.format("%s, type: %s, attack sheet: %s", super.toString(), weaponType, attackSheet);
	}
}

The generated XML:
<store>
  <items>
    <weapon>
      <id>1</id>
      <name>Short sword</name>
      <inventorySheet>data/items/shortsword.png</inventorySheet>
      <weaponType>swords</weaponType>
      <attackSheet>data/sprites/swordattack.png</attackSheet>
    </weapon>
    <weapon>
      <id>2</id>
      <name>Bastard sword</name>
      <inventorySheet>data/items/bastardsword.png</inventorySheet>
      <weaponType>swords</weaponType>
      <attackSheet>data/sprites/swordattack.png</attackSheet>
    </weapon>
    <weapon>
      <id>3</id>
      <name>Long sword</name>
      <inventorySheet>data/items/longsword.png</inventorySheet>
      <weaponType>swords</weaponType>
      <attackSheet>data/sprites/swordattack.png</attackSheet>
    </weapon>
    <armor>
      <id>4</id>
      <name>Studded leather armor</name>
      <inventorySheet>data/items/studdedleather.png</inventorySheet>
      <armorType>Chest</armorType>
      <armorValue>20</armorValue>
    </armor>
  </items>
</store>