老师来康康，有几个问题

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE teaching-plan SYSTEM "teaching-plan.dtd">
<teaching-plan>
<course id="001">
<course-name>大学英语</course-name>
<class-hour>36</class-hour>
<exam-form>考试</exam-form>
</course>
<course id="002">
<course-name>高等数学</course-name>
<class-hour>70</class-hour>
<exam-form>考试</exam-form>
</course>
<course id="003">
<course-name>计算机应用基础</course-name>
<class-hour>108</class-hour>
<exam-form>上机考试</exam-form>
</course>
</teaching-plan>
=====================================
package com.imooc.dom4j;

import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class PlanReader {
	public void readXml() {
		String file="E:/Users/Weng/eclipse-workspace/mxl/src/teaching-plan.xml";
		SAXReader reader=new SAXReader();
		try {
			Document document=reader.read(file);
			Element root=document.getRootElement();
			List<Element> courses=root.elements("course");
			for(Element course:courses) {
				
				System.out.println(course.attribute("id").getText());
				System.out.println(course.element("course-name").getText());
				System.out.println(course.element("class-hour").getText());
				System.out.println(course.element("exam-form").getText());
				System.out.println("==============================");
			}
		} catch (DocumentException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	public static void main(String args[]) {
		PlanReader reader=new PlanReader();
		reader.readXml();
	}
}
=======================================================
package com.imooc.dom4j;

import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class PlanWrite {
	public void writeXml() {
		String file="E:/Users/Weng/eclipse-workspace/mxl/src/teaching-plan.xml";
		SAXReader reader=new SAXReader();
		try {
			Document document=reader.read(file);
			Element root=document.getRootElement();
			Element course=root.addElement("course");
			course.addAttribute("id","0810");
			Element name=course.addElement("course-name");
			name.setText("数据结构");
			course.addElement("class-hour").setText("60");
			course.addElement("exam-form").setText("笔试");
			Writer write=new OutputStreamWriter(new FileOutputStream(file),"UTF-8");
			document.write(write);
			write.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static void main(String args[]) {
		PlanWrite planWrite=new PlanWrite();
		planWrite.writeXml();
	}
}

1. 我这运行写入后，xml没有更新添加的信息，再运行读取，控制台能显示添加的信息，是我哪里写错了吗？读取的文件是存在哪里的啊？

2. 直接运行xml会自动生成一个teaching-plan.out.xml文件，请问这是啥？