无法使用jdom创建xml文件(can not create the xml file using jdom)

 这是我的代码： 
 
import java.io.FileWriter; 
import java.io.IOException; 
import org.jdom2.Attribute; 
import org.jdom2.Document; 
import org.jdom2.Element; 
import org.jdom2.output.Format; 
import org.jdom2.output.XMLOutputter;


try {
    Element FICHADAS = new Element("FICHADAS");
    Document doc = new Document(FICHADAS);
    doc.setRootElement(FICHADAS);
    Element fichada = new Element("fichada");
    fichada.addContent(new Element("N_Terminal").setText("XX"));
    fichada.addContent(new Element("Tarjeta").setText("XX"));
    fichada.addContent(new Element("Fecha").setText("XX"));
    fichada.addContent(new Element("Hora").setText("XX"));
    fichada.addContent(new Element("Causa").setText("XX"));
    doc.getRootElement().addContent(fichada);
    XMLOutputter xmlOutput = new XMLOutputter();
    xmlOutput.setFormat(Format.getPrettyFormat());
    xmlOutput.output(doc, new FileWriter("c:\file.xml"));
} catch(IOException e) {

}
 
 我试图在C：\中找到file.xml，但不在这里，我不知道为什么，控制台告诉我：元素“FICHADAS”无法添加为文档的根目录：内容已经有一个现有的父文件 
 
 // NEW我在想，现在我只需要将新的fichadas添加到现有文档中，不需要每次打开程序时都创建它。 

Here is my code:
 
import java.io.FileWriter; 
import java.io.IOException; 
import org.jdom2.Attribute; 
import org.jdom2.Document; 
import org.jdom2.Element; 
import org.jdom2.output.Format; 
import org.jdom2.output.XMLOutputter;


try {
    Element FICHADAS = new Element("FICHADAS");
    Document doc = new Document(FICHADAS);
    doc.setRootElement(FICHADAS);
    Element fichada = new Element("fichada");
    fichada.addContent(new Element("N_Terminal").setText("XX"));
    fichada.addContent(new Element("Tarjeta").setText("XX"));
    fichada.addContent(new Element("Fecha").setText("XX"));
    fichada.addContent(new Element("Hora").setText("XX"));
    fichada.addContent(new Element("Causa").setText("XX"));
    doc.getRootElement().addContent(fichada);
    XMLOutputter xmlOutput = new XMLOutputter();
    xmlOutput.setFormat(Format.getPrettyFormat());
    xmlOutput.output(doc, new FileWriter("c:\file.xml"));
} catch(IOException e) {

}
 
i try to find the file.xml in C:\ but is not here and I don't know why, and the console show me that: The element "FICHADAS" could not be added as the root of the document: The Content already has an existing parent document
 
//NEW I was thinking, and now i only need to add the new fichadas to the existing document, not need to create it every time that i opened the program.

原文：https://stackoverflow.com/questions/29790834