如何从java中删除子元素? [英] How to remove child element from XML in java?
问题描述
这是我的XML文件
<?xml version="1.0" encoding ="utf-8" ?>
<mcss>
<quest ans="1">
<question><![CDATA[Write 5x= 3y-1 as linear equation form.]]></question>
<options>
<option><![CDATA[5x-3y+1=0]]></option>
<option><![CDATA[-5x-3y-1=0]]></option>
<option><![CDATA[5x+3y+1=0]]></option>
</options>
<explaination><![CDATA[Recall the linear equation in two variables form.]]></explaination>
</quest>
</mcss>
我只想从我的xml中删除第二个选项。
我的java代码从我的选项元素中删除所有选项。通过使用 option.getParentElement()。removeChild(option);
I just want to remove 2nd one option from my xml.
My java code remove all option from my options element. by using option.getParentElement().removeChild("option");
try {
String path="D://test//n2027_set1.xml";
File structureXml = new File(path);
SAXBuilder saxb = new SAXBuilder();
Document document = saxb.build(structureXml);
Element rootElement = document.getRootElement();
XMLOutputter xmlOutput = new XMLOutputter();
List qestList = rootElement.getChildren();
for (int i = 0; i < qestList.size(); i++) {
Element quesList = (Element) qestList.get(i);
System.out.println(quesList.getAttributeValue("ans"));
//change ans field
quesList.setAttribute("ans", ""+i);
List qList = quesList.getChildren();
for(int a=0;a< qList.size();a++) {
Element ques =(Element) qList.get(a);
if(ques.getAttributeValue("file")!=null){
//read xml
System.out.println(ques.getAttributeValue("file"));
//write xml attribute
//System.out.println(ques.setAttribute("file","dasd"+a));
}
if(ques.getName().equalsIgnoreCase("question")){
//read
System.out.println(ques.getTextTrim());
ques.addContent(new CDATA(ques.getTextTrim()));
}
if (ques.getName().equalsIgnoreCase("options")) {
List optList = ques.getChildren();
for (int k = 0; k < optList.size(); k++) {
Element option = (Element) optList.get(k);
if(option.getName().equalsIgnoreCase("option")){
//read
option.getParentElement().removeChild("option");
}
}
}
if(ques.getName().equalsIgnoreCase("explaination")){
ques.removeContent();
ques.addContent(new CDATA("explaination"+a));
}
}
}
FileOutputStream file=new FileOutputStream(path);
xmlOutput.output(document, file);
}catch (JDOMException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
我的输出是:
<?xml version="1.0" encoding ="utf-8" ?>
<mcss>
<quest ans="1">
<question><![CDATA[Write 5x= 3y-1 as linear equation form.]]></question>
<options>
</options>
<explaination><![CDATA[Recall the linear equation in two variables form.]]></explaination>
</quest>
</mcss>
但我想要这样。
<?xml version="1.0" encoding ="utf-8" ?>
<mcss>
<quest ans="1">
<question><![CDATA[Write 5x= 3y-1 as linear equation form.]]></question>
<options>
<option><![CDATA[5x-3y+1=0]]></option>
<option><![CDATA[-5x-3y-1=0]]></option>
</options>
<explaination><![CDATA[Recall the linear equation in two variables form.]]></explaination>
</quest>
</mcss>
推荐答案
Element.removeChild 将仅删除具有给定名称的第一个孩子。您可以使用 Element.removeContent(int index)通过索引删除子元素
Element.removeChild will remove only the first child with the given name. You can use Element.removeContent(int index) to remove child element by index
if (ques.getName().equalsIgnoreCase("options")) {
ques.removeContent(2);
}
或 Element.removeContent(Content content)删除特定元素。
if (ques.getName().equalsIgnoreCase("options")) {
List<Element> options = ques.getChildren("option");
if(options.size()>2) {
Element optionToRemove = options.get(2);
ques.removeContent(optionToRemove);
}
}
你说要删除第二个选项,但是在你的例子中,第三个被删除。我有点困惑,所以如果有必要改变指数。
You said you want to remove the second option, but in your example third one is removed. I'm slightly confused, so change index if necessary.
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