htmlparser-user

[Htmlparser-user] NullPointer Exception: NodeList.add method, htmlparser 1_5

[Riaz u. <ru...@ya...>]

Hi,
I have attached the procedure below, now when I call this procedure it returns a null pointer excetion in the add method. It was working fine when I had it in the main function, but it does not run when I created this procedure, I think I need some java help on this, can someone suggest what I can do?

public static NodeList extractLinkFromSpanTag(String url) throws ParserException
    {
        int i =0;
        
        NodeList nodelistOfLinks = null;
        Parser parser = new Parser(url);
// Step 2. Collecting Tags in a list.
            NodeList list = parser.parse (null);
           
            //news links are at the span tag (time), spanList stores the span tags
// Step 3. Keep only the SPAN tags in spanList.
            NodeList listOfSpanTags = list.extractAllNodesThatMatch(new TagNameFilter ("SPAN"),true);
            
         while(i < listOfSpanTags.size())
            { // Beginning While loop to extract links
                Span spanTag = (Span)listOfSpanTags.elementAt(i);
//                System.out.println(listOfSpanTags.size());
//              We only need SPAN tags with attribute "class = 'recenttimedate'"
//              Move to the link in the span tag
                if(spanTag.getText().equals("span class=recenttimedate"))
                    nodelistOfLinks.add(listOfSpanTags.elementAt(i).getParent());
                i++;
            }// End of while loop to extract links
            while(i < nodelistOfLinks.size())
            {
        System.out.println(nodelistOfLinks.elementAt(i));
        i++;
            }
        
        return nodelistOfLinks;
    }
		
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Re: [Htmlparser-user] NullPointer Exception: NodeList.add method, htmlparser 1_5

[Ian M. <ian...@gm...>]

The stack trace will tell you which line the NullPointerException was
thrown on. Why don't you tell us which line it's occuring on? That
will help pin it down.

Ian

On 3/15/06, Riaz uddin <ru...@ya...> wrote:
> Hi,
> I have attached the procedure below, now when I call this procedure it
> returns a null pointer excetion in the add method. It was working fine wh=
en
> I had it in the main function, but it does not run when I created this
> procedure, I think I need some java help on this, can someone suggest wha=
t I
> can do?
>
> public static NodeList extractLinkFromSpanTag(String url) throws
> ParserException
>     {
>         int i =3D0;
>
>         NodeList nodelistOfLinks =3D null;
>         Parser parser =3D new Parser(url);
> // Step 2. Collecting Tags in a list.
>             NodeList list =3D parser.parse (null);
>
>             //news links are at the span tag (time), spanList stores the
> span tags
> // Step 3. Keep only the SPAN tags in spanList.
>             NodeList listOfSpanTags =3D list.extractAllNodesThatMatch(new
> TagNameFilter ("SPAN"),true);
>
>          while(i < listOfSpanTags.size())
>             { // Beginning While loop to extract links
>                 Span spanTag =3D
> (Span)listOfSpanTags.elementAt(i);
> //                System.out.println(listOfSpanTags.size());
> //              We only need SPAN tags with attribute "class =3D
> 'recenttimedate'"
> //              Move to the link in the span tag
>                 if(spanTag.getText().equals("span class=3Drecenttimedate"=
))
>
> nodelistOfLinks.add(listOfSpanTags.elementAt(i).getParent());
>                 i++;
>             }// End of while loop to extract links
>             while(i < nodelistOfLinks.size())
>             {
>         System.out.println(nodelistOfLinks.elementAt(i));
>          i++;
>             }
>
>         return nodelistOfLinks;
>     }
>
>  ________________________________
> Yahoo! Mail
>  Bring photos to life! New PhotoMail makes sharing a breeze.
>
>
>

Re: [Htmlparser-user] NullPointer Exception: NodeList.add method, htmlparser 1_5

[Riaz u. <ru...@ya...>]

The error is occuring at this statement:

nodelistOfLinks.add(listOfSpanTags.elementAt(i).getParent());


Ian Macfarlane <ian...@gm...> wrote: The stack trace will tell you which line the NullPointerException was
thrown on. Why don't you tell us which line it's occuring on? That
will help pin it down.

Ian

On 3/15/06, Riaz uddin  wrote:
> Hi,
> I have attached the procedure below, now when I call this procedure it
> returns a null pointer excetion in the add method. It was working fine when
> I had it in the main function, but it does not run when I created this
> procedure, I think I need some java help on this, can someone suggest what I
> can do?
>
> public static NodeList extractLinkFromSpanTag(String url) throws
> ParserException
>     {
>         int i =0;
>
>         NodeList nodelistOfLinks = null;
>         Parser parser = new Parser(url);
> // Step 2. Collecting Tags in a list.
>             NodeList list = parser.parse (null);
>
>             //news links are at the span tag (time), spanList stores the
> span tags
> // Step 3. Keep only the SPAN tags in spanList.
>             NodeList listOfSpanTags = list.extractAllNodesThatMatch(new
> TagNameFilter ("SPAN"),true);
>
>          while(i < listOfSpanTags.size())
>             { // Beginning While loop to extract links
>                 Span spanTag =
> (Span)listOfSpanTags.elementAt(i);
> //                System.out.println(listOfSpanTags.size());
> //              We only need SPAN tags with attribute "class =
> 'recenttimedate'"
> //              Move to the link in the span tag
>                 if(spanTag.getText().equals("span class=recenttimedate"))
>
> nodelistOfLinks.add(listOfSpanTags.elementAt(i).getParent());
>                 i++;
>             }// End of while loop to extract links
>             while(i < nodelistOfLinks.size())
>             {
>         System.out.println(nodelistOfLinks.elementAt(i));
>          i++;
>             }
>
>         return nodelistOfLinks;
>     }
>
>  ________________________________
> Yahoo! Mail
>  Bring photos to life! New PhotoMail makes sharing a breeze.
>
>
>


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Re: [Htmlparser-user] NullPointer Exception: NodeList.add method, htmlparser 1_5

[Ian M. <ian...@gm...>]

Looks to me like nodelistOfLinks is null. First of all you have this
line of code:

NodeList nodelistOfLinks =3D null;

Then the next line of code that mentions the nodelistOfLinks object is:

nodelistOfLinks.add(listOfSpanTags.elementAt(i).getParent());

So you're trying to use a method on a null object. Instead of:

NodeList nodelistOfLinks =3D null;

You probably want:

NodeList nodelistOfLinks =3D new NodeList();


Ian

On 3/16/06, Riaz uddin <ru...@ya...> wrote:
> The error is occuring at this statement:
>
> nodelistOfLinks.add(listOfSpanTags.elementAt(i).getParent());
>
>
> Ian Macfarlane <ian...@gm...> wrote:
>
>  The stack trace will tell you which line the NullPointerException was
> thrown on. Why don't you tell us which line it's occuring on? That
> will help pin it down.
>
> Ian
>
> On 3/15/06, Riaz uddin wrote:
> > Hi,
> > I have attached the procedure below, now when I call this procedure it
> > returns a null pointer excetion in the add method. It was working fine
> when
> > I had it in the main function, but it does not run when I created this
> > procedure, I think I need some java help on this, can someone suggest w=
hat
> I
> > can do?
> >
> > public static NodeList extractLinkFromSpanTag(String url) throws
> > ParserException
> > {
> > int i =3D0;
> >
> > NodeList nodelistOfLinks =3D null;
> > Parser parser =3D new Parser(url);
> > // Step 2. Collecting Tags in a list.
> > NodeList list =3D parser.parse (null);
> >
> > //news links are at the span tag (time), spanList stores the
> > span tags
> > // Step 3. Keep only the SPAN tags in spanList.
> > NodeList listOfSpanTags =3D list.extractAllNodesThatMatch(new
> > TagNameFilter ("SPAN"),true);
> >
> > while(i < listOfSpanTags.size())
> > { // Beginning While loop to extract links
> > Span spanTag =3D
> > (Span)listOfSpanTags.elementAt(i);
> > // System.out.println(listOfSpanTags.size());
> > // We only need SPAN tags with attribute "class =3D
> > 'recenttimedate'"
> > // Move to the link in the span tag
> > if(spanTag.getText().equals("span class=3Drecenttimedate"))
> >
> > nodelistOfLinks.add(listOfSpanTags.elementAt(i).getParent());
> > i++;
> > }// End of while loop to extract links
> > while(i < nodelistOfLinks.size())
> > {
> > System.out.println(nodelistOfLinks.elementAt(i));
> > i++;
> > }
> >
> > return nodelistOfLinks;
> > }
> >
> > ________________________________
> > Yahoo! Mail
> > Bring photos to life! New PhotoMail makes sharing a breeze.
> >
> >
> >
>
>
> -------------------------------------------------------
> This SF.Net email is sponsored by xPML, a groundbreaking scripting langua=
ge
> that extends applications into web and mobile media. Attend the live webc=
ast
> and join the prime developer group breaking into this new coding territor=
y!
> http://sel.as-us.falkag.net/sel?cmd=3Dlnk&kid=110944&bid$1720&dat=121642
> _______________________________________________
> Htmlparser-user mailing list
> Htm...@li...
> https://lists.sourceforge.net/lists/listinfo/htmlparser-user
>
>
>
>  ________________________________
> Relax. Yahoo! Mail virus scanning helps detect nasty viruses!
>
>