Processing 1.0 - Processing Discourse - iterating past empty rss feeds

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iterating past empty rss feeds (Read 638 times)

o.o

iterating past empty rss feeds
Jun 16^th, 2009, 12:24pm

hello,

I am fairly new to programming and working with xml feed.
i am trying to parse through a series of feeds using the xml library and retrieve some data for a visualization project.

String url= "-----------------------------"
+ X + "-----------";

Some of those feeds are empty.
How do i catch that and move on to the next feed( X++) or any other feed(random X) before i start calling:
XMLElement report= new XMLElement (this, url);
and getting a Nested Exception error:
at processing.xml.StdXMLParser.parse(StdXMLParser.java:204)

(The actual parsing of a 'fixed' feed is working fine).

Thanks,

o

NoahBuddy Ex Member	Re: iterating past empty rss feeds Reply #1 - Jun 16^th, 2009, 1:27pm You could use a try/catch block and parse it within the try{} section. Any time you get a Nested Exception (or some kind), increment X inside the catch{} block.

o:o

Re: iterating past empty rss feeds
Reply #2 - Jun 16^th, 2009, 3:52pm

Thank you NoahBuddy.

I have tried a few try and catch block, but i have to say i am not so familiar with them. Here is a stripped down version of the problem i am hoping to solve: As you press enter, at some point it will crash, therefore the initial question. Maybe you or someone could help me with the following code.
Thank you.
o:o

note: i have taken out "http" from the url as i am told i need 5 posts before sending a web link.

import processing.xml.*;
PFont f_s, f_m, f_l;
int x=1;

void setup()
{
size(800, 600);
f_s= createFont("SanSerif", 12);
f_m= createFont("SanSerif", 16);
f_l= createFont("Calibri_bold", 22);
}

void draw()
{
background(0);
// try{
String url= //magicseaweed.com/syndicate/rss/index.php?id="+ x + "&unit=";
XMLElement report= new XMLElement (this, url);

//if(report!=null){
//println(report);
// }
// }
//catch(IOException e){
// x++;
// }

//////////////////////////////////////////////////////////////////////
//Get the location // "<link>/Newquay-Fistral-Surf-Report/1/</link>"

XMLElement Location= report.getChild("channel/title");
// println(Location);
String locationStg= giveTextInBetween( Location.getContent(), "Latest", "Surf");

XMLElement reportNum= report.getChild("channel/link");

String reportNum2= giveTextInBetween( reportNum.getContent(), "Report/", "/");
//println(reportNum2);
String Num= nf(parseInt(reportNum2), 4 );
// println(Num);
textFont(f_l);
fill(255);
text(Num + ": " + locationStg, 10, 25);

}
//function taken from D.Shiffman
String giveTextInBetween (String s, String startTag, String endTag){
String found= "";
int startIndex= s.indexOf(startTag);
if(startIndex==-1) return "";
startIndex += startTag.length();
int endIndex= s.indexOf(endTag, startIndex);
if(endIndex==-1) return "";
return s.substring(startIndex, endIndex);
}

void keyPressed(){
if (key== '\n'){
x= (int)random(1, 1062);
}
}

NoahBuddy

Re: iterating past empty rss feeds
Reply #3 - Jun 16^th, 2009, 4:28pm

Inside draw():
Code:

...
//Variables need to be declared outside the try/catch block if you use them later
  String url = null;
  XMLElement report = null;
  
  try{
    url= "http://magicseaweed.com/syndicate/rss/index.php?id="+ x + "&unit=";
    report = new XMLElement(this, url);
  } catch (Exception er) {
    er.printStackTrace();//Wha happened?
    x++;
    return;
  }
...

I would also recommend putting the parsing code into the keyPressed method. Not only does it send fewer requests to the address (if that would become a problem), but it will print fewer red error messages when it fails to parse (instead of the default 60 frames per second).

If you are not planning to add animation, you can use noLoop(); inside the setup method, then call redraw() on a key press.

o:o YaBB Newbies Offline Posts: 3	Re: iterating past empty rss feeds Reply #4 - Jun 16^th, 2009, 4:41pm Thanks a lot NoahBuddy! it's working fine now. Really appreciated! o:o

o:o YaBB Newbies Offline Posts: 3	Re: iterating past empty rss feeds Reply #5 - Jun 16^th, 2009, 5:07pm ...as well as for your extra tips! o:o

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