Question

I’m trying to put both Strings and Nodes onto a Stack. I use the NodeList method item(int) to obtain a Node from the NodeList. Then, I push this Node to the Stack. My only problem is that I doesn’t see it as a Node unless I have something wrong.

When I call getClass() method on the Node and it returns this:

class com.sun.org.apache.xerces.internal.dom.DeferredElementImpl

When I call that same method on NodeList (getClass()), it returns this:

class com.sun.org.apache.xerces.internal.dom.DeepNodeListImpl

Both times when I call the getClass() method, it is before I put it on the Stack. I want to be able to any different Objects onto a Stack, and be able to filter through all the objects on the Stack to figure out which class they belong to. Thanks!

Answer 1

Node and NodeList are interfaces not class.

instanceof was made for you.

This code :

DocumentBuilderFactory dbf   = DocumentBuilderFactory.newInstance();
DocumentBuilder        db    = dbf.newDocumentBuilder();
Document               doc   = db.parse( new File( "build.xml" ));
NodeList               nodes = doc.getElementsByTagName( "target" );
System.err.println( nodes instanceof NodeList );
System.err.println( nodes.item( 0 ) instanceof Node );
System.err.println( nodes.item( 0 ) instanceof Element );

outputs:

true
true
true

You may write, after stack.pop(), if( var instance of String ) or if( var instanceof Node )… but IMHO it’s not a good idea to mix different type into a single container.