java如何从for循环中获取指定属性？

Question

我试图得到“Value”字符串，它的NumVotes值最大。 在那之后，我想做一个简单的asserion（我知道怎么做），但我有问题如何获得这个“值”。我对此一无所知

public class DomParserDemo {

    public static void main(String[] args) {

        try {

            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder dbBuilder = dbFactory.newDocumentBuilder();
            InputSource is = new InputSource(new StringReader("<poll name=\"language_dependence\" title=\"Language Dependence\" totalvotes=\"170\"><results><result level=\"1\" value=\"No necessary in-game text\" numvotes=\"168\"/><result level=\"2\" value=\"Some necessary text - easily memorized or small crib sheet\" numvotes=\"0\"/><result level=\"3\" value=\"Moderate in-game text - needs crib sheet or paste ups\" numvotes=\"0\"/><result level=\"4\" value=\"Extensive use of text - massive conversion needed to be playable\" numvotes=\"0\"/><result level=\"5\" value=\"Unplayable in another language\" numvotes=\"2\"/></results></poll>"));
            Document doc = dbBuilder.parse(is);
            doc.getDocumentElement().normalize();
            System.out.println("Root element :" + doc.getDocumentElement().getNodeName());
            NodeList nodeList = doc.getElementsByTagName("result");

            for (int i = 0; i < nodeList.getLength(); i++) {
                Element element = (Element) nodeList.item(i);

                System.out.println("Level = "+ element.getAttribute("level")+", "+
                        "Value = "+element.getAttribute("value")+", "+
                        "NumVotes = "+element.getAttribute("numvotes"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

电流输出：

      Root element :poll
Level = 1, Value = No necessary in-game text, NumVotes = 168
Level = 2, Value = Some necessary text - easily memorized or small crib sheet, NumVotes = 0
Level = 3, Value = Moderate in-game text - needs crib sheet or paste ups, NumVotes = 0
Level = 4, Value = Extensive use of text - massive conversion needed to be playable, NumVotes = 0
Level = 5, Value = Unplayable in another language, NumVotes = 2

Answer 1

您已经在迭代所有元素。通过使用一个变量跟踪到目前为止的最大值，并将其与每个值进行比较，就可以通过一个元素属性找到最大值。您的for循环有点修改：

String targetValue = "";
int maxNumVotes = 0;
for (int i = 0; i < nodeList.getLength(); i++) {
    Element element = (Element) nodeList.item(i);
    int numVotes = Integer.parseInt(element.getAttribute("numvotes"));
    if (numVotes > maxNumVotes) {
        maxNumVotes = numVotes;
        targetValue = element.getAttribute("value");
    }
}
System.out.println("Value: " + targetValue + " NumVotes: " + maxNumVotes);

但是，如果要按投票数对元素进行排序，请将元素添加到列表中，并使用比较器按投票数或任何其他字段进行排序