讀取xml文件並使用Java進行求和

Question

我對Java和xml非常陌生。 我正在嘗試找到一種方法來求和，但是我不確定如何做到這一點。 我已經嘗試了幾件事，但是沒有用。 非常感謝你的幫助。

for (int i = 0; i < clients.getLength(); i++) {
    Element client = (Element) clients.item(i);
    String name = client.getAttribute("name");
    NodeList transactions = client.getElementsByTagName("transaction");

    for(int j=0; j<transactions.getLength(); j++) {
            Element transaction = (Element) transactions.item(j);
            int amount = Integer.parseInt(transaction.getAttribute("amount"));

    }

    System.out.println("Client name : " +name);
    System.out.println("Sum : " );
}

Answer 1

嘗試這個

   for (int i = 0; i < clients.getLength(); i++) {
    Element client = (Element) clients.item(i);
    String name = client.getAttribute("name");
    NodeList transactions = client.getElementsByTagName("transaction");
     int sum =0;
    for(int j=0; j<transactions.getLength(); j++) {
            Element transaction = (Element) transactions.item(j);
            sum = sum + Integer.parseInt(transaction.getAttribute("amount"));

    }

    System.out.println("Client name : " +name);
    System.out.println("Sum : " + sum );
}

Answer 2

使用XPath，這種事情要容易得多（即使您不必使用Java和DOM，也可能不需要）。

XPath xpath = XPathFactory.newInstance().newXPath();
for (int i = 0; i < clients.getLength(); i++) {
    Element client = (Element) clients.item(i);
    int sum = (int)xpath.evaluate("sum(transaction/@amount)", 
                  client, XPathConstants.NUMBER);    
    System.out.println("Client name : " + client.getAttribute("name"));
    System.out.println("Sum : " + sum );
}