Null Pointer Exception in XMl Parsing

Question

I need to parser an Xml Document and store the values in Text File, when i am parsing normal data (If all tags have data) then its working fine, but if any tag doesnt have d

Answer 1

Replace

System.out.println("First Name : " + getTagValue("firstname", eElement));

by

System.out.println("First Name : " + getTagValue("firstname", eElement) == null?"":getTagValue("firstname", eElement));

same thing for the other tags.

Answer 2

This code should work:

// getNode function
private static String getNode(String sTag, Element eElement) {
    //if sTag exists(not null) I get childNodes->nlList
    if (eElement.getElementsByTagName(sTag).item(0)!=null){
        NodeList nlList = eElement.getElementsByTagName(sTag).item(0).getChildNodes();
        //check if child (nlList) contain something
        if ((nlList.getLength() == 0))//if the content is null
            return "";
        //if child contains something extract the value of the first element
        Node nValue = (Node) nlList.item(0);
            return nValue.getNodeValue();
    }
    return "";
}

Answer 3

NodeList nlList = eElement.getElementsByTagName(sTag).item(0).getChildNodes();

The above line gets the child nodes of the element with the given tag name. If this element doesn't have data, the returned node list is empty.

Node nValue = (Node) nlList.item(0);

The above line gets the first element from the empty node list. Since the list is empty, 0 is an invalid index, and as per the documentation, null is returned

return nValue.getNodeValue();

The above line thus calls a method on a null variable, which causes the NPE.

You should test if the list is empty, and return what you want (an empty string, for example), if it's the case:

if (nList.getLength() == 0) {
    return "";
}
Node nValue = (Node) nlList.item(0);
return nValue.getNodeValue();

Answer 4

Just check that the object is not null:

private static String getTagValue(String tag, Element eElement) {
    NodeList nlList = eElement.getElementsByTagName(tag).item(0).getChildNodes();
    Node nValue = (Node) nlList.item(0);
    if(nValue == null) 
        return null;
    return nValue.getNodeValue();
}

String salary = getTagValue("Department", eElement);
if(salary != null) {
    System.out.println("Salary : " + getTagValue("Department", eElement));
}