Five Minute Tutorial

Version 2 by Robin Shen
on Feb 10, 2010 04:10.

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Version 3 by Robin Shen
on Feb 10, 2010 04:25.

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		We demonstrate usage of this tool with a simple tutorial. Assume a _Task_ class below with a _prioritized_ field indicating whether it is a prioritized task:
		{code}
		package example;

		public class Task {
		public boolean prioritized;
		}
		{code}
		With XStream, we can serialize object of this class to XML like below:
		{code}
		Task task = new Task();
		task.setPrioritized(true);
		String xml = new XStream().toXML(task);
		saveXmlToFileOrDatabase(xml);
		{code}
		Resulting XML will be:
		{code}
		<example.Task>
		<prioritized>true</prioritized>
		</example.Task>
		{code}
		And you can deserialize the XML to get back task object:
		{code}
		String xml = readXmlFromFileOrDatabase();
		Task task = (Task)(new XStream(new DomDriver()).fromXML(xml));
		{code}
		Everything is fine. Now we find a prioritized flag is not enough for a task, we need to enhance it to take a numeric priority field ranges from 1 to 10, so the task class becomes:
		Everything is fine. Now we find a prioritized flag is not enough, so we enhance the Task class to use a numeric priority field ranging from 1 to 10:
		{code}
		package example;

		public class Task {
		public int priority;
		}
		{code}
		However deserialization of previously saved xml is no longer possible since the new Task class is no longer compatible.