Read xml file and make summation with java

Question

I am very new to java and xml. I am trying to find a way to make the summation of the amount but I am not sure how to do this. I tried a couple of things already but it didn't work. Thanks a lot for your help.

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

try this

   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

This kind of thing is much easier with XPath (even if you have to use Java and DOM, which you probably don't).

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 );
}