java - 使用 XML 填充 JComboBox - 缺少一些内容

Question

又是我。我有以下 XML 文件:

<?xml version="1.0"?>
<components>
    <resources>
        <resource id="House">
            <id>int</id>
            <type>string</type>
            <maxUsage>float</maxUsage>
            <minUsage>float</minUsage>
            <averageUsage>float</averageUsage>
        </resource>
        <resource id="Commerce">
            <id>int</id>
            <type>string</type>
            <maxUsage>float</maxUsage>
            <minUsage>float</minUsage>
            <averageUsage>float</averageUsage>
        </resource>
        <resource id="Industry">
            <id>int</id>
            <type>string</type>
            <maxUsage>float</maxUsage>
            <minUsage>float</minUsage>
            <averageUsage>float</averageUsage>
        </resource>
    </resources>
    <agregatorsType1>
        <agregator1 id="CSP">
            <id>int</id>
            <type>string</type>
        </agregator1>
        <agregator1 id="Microgrid">     
            <id>int</id>
            <type>string</type>
        </agregator1>
    </agregatorsType1>
    <soagregatorsType0>
        <agregator0 id="VPP">
            <id>int</id>
            <type>string</type>
        </agregator0>
    </agregatorsType0>
</components>

我想用每个资源(房屋、商业和工业)的 id 填充 JComboBox。

我有以下方法:

public static String[] readResourcesXML(String fileName) throws IOException, ClassNotFoundException, Exception {


//Gets XML
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = factory.newDocumentBuilder();
Document documento = docBuilder.parse(fileName);

//Searches all text 
documento.getDocumentElement().normalize();

//Gets elements from xml 
Element raiz = documento.getDocumentElement();
NodeList listaResources = raiz.getElementsByTagName("resources");

//Search all resources 
int tam = listaResources.getLength();
String[] vecResources = new String[tam];

for (int i = 0; i < tam; i++) {
    Element elem = (Element) listaResources.item(i);           
    vecResources[i] =  elem.getAttribute("/resource/@id");
}
    //returns an array with all the id's of the resources
    return vecResources;
}

注意:字符串文件名具有以下值:“src\configs\features.xml”

问题是，JComboBox 始终为空。我错过了什么？

谢谢;)

Answer 1

Element#getAttribute直接从Elements而不是从嵌套元素检索属性。您需要改为迭代 resource:

NodeList listaResources = raiz.getElementsByTagName("resource");

int tam = listaResources.getLength();
String[] vecResources = new String[tam];

for (int i = 0; i < tam; i++) {
   Element elem = (Element) listaResources.item(i);      
   System.out.println(elem);
   vecResources[i] =  elem.getAttribute("id"); // change to id
}