Object references

Overview

This section explains how WOX handles object references. We will use the Product class below, which has five fields.

//Java
public class Product {
    private String name;
    private double price;
    private int grams;
    private boolean registered;
    private char category;
    //constructors and methods omitted
}

//C#
public class Product {
    private String name;
    private double price;
    private int grams;
    private bool registered;
    private char category;
    //constructors and methods omitted
}

Serializing an array with duplicate Product objects to XML

An array of six Product objects is created below. The array contains some duplicate objects: product p1 is duplicated three times in the array, and product p3 is duplicated twice.

//Java
Product p1 = new Product("Baked beans", 1.75, 250, true, 'B');
Product p2 = new Product("Basmati Rice", 3.89, 750, true, 'R');
Product p3 = new Product("White bread", 1.06, 300, false, 'H');
Product[] products = new Product[]{p1, p2, p1, p3, p3, p1};

//C#
Product p1 = new Product("Baked beans", 1.75, 250, true, 'B');
Product p2 = new Product("Basmati Rice", 3.89, 750, true, 'R');
Product p3 = new Product("White bread", 1.06, 300, false, 'H');
Product[] products = new Product[]{p1, p2, p1, p3, p3, p1};

Lets see how WOX handle object references. We use the save method of the Easy class to serialize our array of Product objects to XML, and store it to the specified file.

In Java you will require woxSerializer.jar and jdom.jar files in the classpath. In C# you will require woxSerializer.dll.

//Java
String filename = "arrayDuplicateProducts.xml";
Easy.save(products, filename);

//C#
String filename = "arrayDuplicateProducts.xml";
Easy.save(products, filename);

The array represented in XML is shown below.

<object type="array" elementType="Product" length="6" id="0">
    <object type="Product" id="1">
        <field name="name" type="string" value="Baked beans" />
        <field name="price" type="double" value="1.75" />
        <field name="grams" type="int" value="250" />
        <field name="registered" type="boolean" value="true" />
        <field name="category" type="char" value="\u0042" />
    </object>
    <object type="Product" id="2">
        <field name="name" type="string" value="Basmati Rice" />
        <field name="price" type="double" value="3.89" />
        <field name="grams" type="int" value="750" />
        <field name="registered" type="boolean" value="true" />
        <field name="category" type="char" value="\u0052" />
    </object>
    <object idref="1" />
    <object type="Product" id="3">
        <field name="name" type="string" value="White bread" />
        <field name="price" type="double" value="1.06" />
        <field name="grams" type="int" value="300" />
        <field name="registered" type="boolean" value="false" />
        <field name="category" type="char" value="\u0048" />
    </object>
    <object idref="3" />
    <object idref="1" />
</object>

The duplicated Product objects are not duplicated in the XML representation. They are referenced by using the idref attribute, which actually refers to the unique id given to every object. Look at the XML representation above and you will find the three object references for the duplicated objects (two for product p1 identified by id="1", and one for product p3, identified by id="3").

De-serializing an array of duplicate Product objects back from XML

We can use the load method of the Easy class de-seralize the array back from XML either to Java or C#. Note that WOX in Java does not require the Product class to have a default constructor; but WOX in C# does.

//Java
Product[] newProducts = (Product[])Easy.load(filename);

//C#
Product[] newProducts = (Product[])Easy.load(filename);

The array has been reconstructed, and you can now iterate to display its elements. Observe that the object references are also preserved.