N-D Primitive Arrays

Overview

This section covers multi-dimensional primitive arrays. Multi-dimensional primitive arrays can be serialized as stand-alone arrays, as shown in the 1-D Primitive Arrays section, or as part of a class.

We mentioned in the previous section that primitive arrays are treated differently from object arrays, because they are serialized in a more efficient way. We will show you how multi-dimensional arrays are serialized when they are declared inside a class (as fields). The code is provided in Java and C#.

The TestMultiArray class

The TestMultiArray class has only one field, which is a 2-dimensional array of int.

//Java
public class TestMultiArray {
    private int[][] matrix;
}

//C#
public class TestMultiArray {
    private int[][] matrix;
}

Serializing the TestMultiArray class to XML

A TestMultiArray object is created below.

//Java
TestMultiArray test = new TestMultiArray(new int[][]{ {23, 56, 89, 36, 68},
                                                      {87, 64, 88, 32},
                                                      {78, 80, 21, 29, 34, 67} } );

//C#
TestMultiArray test = new TestMultiArray(new int[][]{ new int[]{23, 56, 89, 36, 68},
                                                      new int[]{87, 64, 88, 32},
                                                      new int[]{78, 80, 21, 29, 34, 67} } );

We use the save method of the Easy class to serialize the object to XML and store it to the specified XML 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 = "testMultiArray.xml";
Easy.save(test, filename);

//C#
String filename = "testMultiArray.xml";
Easy.save(test, filename);

The TestMultiArray object respresented in XML is below. The Java object and the C# object will have the same XML representation.

<object type="TestMultiArray" id="0">
    <field name="matrix">
        <object type="array" elementType="int[]" length="3" id="1">
            <object type="array" elementType="int" length="5" id="2">23 56 89 36 68</object>
            <object type="array" elementType="int" length="4" id="3">87 64 88 32</object>
            <object type="array" elementType="int" length="6" id="4">78 80 21 29 34 67</object>
        </object>
    </field>
</object>

The XML is simple and easy to understand. The root is an object element, with type attribute equals TestMultiArray, which is the class of the root object. The root element has one child: a field element, which is the 2-dimensional primitive array. Since this is a 2-dimensional array, it is actually serialized as an array of arrays. It is an array of 3 elements of type int[], where every element is an array of type int. The first array has 5 elements, the second array has 4 elements, and the last array has 6 elements. The elements of each array are represented as a string separated by spaces.

Please note that every object has an id attribute, which is used to handle object references. Arrays of more than 2 dimensions are represented in XML following the same idea shown in this example.

De-serializing the TestMultiArray class back from XML

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

//Java
TestMultiArray newTest = (TestMultiArray)Easy.load(filename);

//C#
TestMultiArray newTest = (TestMultiArray)Easy.load(filename);

The TestMultiArray object has been reconstructed from XML to your chosen programming language. You can iterate the matrix 2-dimensional array to display its elements.