android xml解析?报错

android刚入门，代码报错，请大家指引一下。

xml文件解析报错：如下信息

org.xmlpull.v1.XmlPullParserException: version expected (position:unknown @1 :38 in java.io.InputStreamReader@40d14740)

package service;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import org.xmlpull.v1.XmlPullParser;

import android.util.Xml;
import domain.Person;

public class PersonService {
	//static方法 ，不需要用到成员变量
	public static List<Person> getPersons(InputStream xml) throws Exception{
		List<Person> persons=null;
		Person person=null;
		XmlPullParser pullParser=Xml.newPullParser();
		pullParser.setInput(xml, "UTF-8");
		int event=pullParser.getEventType();
		while(event!=XmlPullParser.END_DOCUMENT){			
			switch (event) {
			case XmlPullParser.START_DOCUMENT:
				persons=new ArrayList<Person>();
				break;
			case XmlPullParser.START_TAG:
				if("person".equals(pullParser.getName())){
					int id=Integer.parseInt(pullParser.getAttributeValue(0));
					person=new Person();
					person.setId(id);
				}
				if("name".equals(pullParser.getName())){
					String name=pullParser.nextText();
					person.setName(name);
				}
				if("age".equals(pullParser.getName())){
					int age=Integer.parseInt(pullParser.nextText());
					person.setAge(age);
				}
				break;
			case XmlPullParser.END_TAG:
				if("person".equals(pullParser.getName())){
					persons.add(person);
					person=null;
				}
				break;
			}			
			event=pullParser.next();  //单元测试时，这一行报错
	}
		return persons;
}
}