Appending XMLElement array?

Programming Questions

velvetkev..

in Programming Questions • 2 years ago

Hi folks,

I'm working on some sketches using the Guardian Open Platform API which returns results as an XMLElement, which I can then run getChildren() on to get each result. This will return up to 50 results as a single XMLElement, so to get more than 50 results I have to run the query multiple times and combine the results in Processing. The issue I'm having is that I want to combine the XMLElement arrays returned from getChildren() , but I'm unsure how to go about this. Using

results= append(results, responseChild);

where results and reponseChild are both XMLElement arrays gives me the error "cannot convert from Object to XMLElement[]".

Can anyone suggest what is going wrong here?

Replies(5)

PhiLho

Re: Appending XMLElement array?

2 years ago

Probably need to use:
results= (XMLElement[]) append(results, responseChild);

velvetkev..

Re: Re: Appending XMLElement array?

2 years ago

Thanks. That throws up the error "IllegalArgumentException: array element type mismatch"- I'm baffled as to why that would be the case.

If it's any help, this is the code I'm working with. Line 42 is the line being highlighted with the error.

Any ideas much appreciated!

int page=1; //page number being called
int pages; //total pages available
int total; //total entries available
PFont f;
//set search parameters
String api= "xxxx"; //you'll need to get an API key to run it!
String url="http://content.guardianapis.com/search?";
String search= "carrot";
String section = "news";
XMLElement response;
XMLElement[] results;
XMLElement[] responseChild;
String constructQuery() { //construct the search terms
String q= url + "q=" + search + "&section=" + section+"&page=" + page
+ "&page-size=10&order-by=newest" + "&format=xml&api-key=" + api;
return q;
}
void setup() {
size(1000, 1000);
smooth();
noLoop();
f= loadFont("ASCII-12.vlw");
textFont(f, 12);
String query= constructQuery();
response= new XMLElement(this, query);
pages=response.getIntAttribute("pages"); //send initial query to establish how many pages of XML we'll need to go through to get all results
total=response.getIntAttribute("0");// and how many results there are in total
results= new XMLElement[total]; //initialise string array to hold the results(there are 10 items per page by default)
for(int i=0; i<pages; i++) {
page=i+1;
query= constructQuery();
response= new XMLElement(this, query); //run the query for each page
responseChild= response.getChildren("results/content"); //get each XML story item
results= (XMLElement[])append(results, responseChild); //put the results into one array
}
}
void draw() {
background(255);
fill(0);
translate(width/2, height/2);
for(int i=0; i<results.length; i++) {
String headline= results[i].getStringAttribute("web-title"); //run through each result and print to the canvas.
float angle=(TWO_PI/total)*i;
float xpos= cos(angle)*75;
float ypos= sin(angle)*75;
pushMatrix();
translate(xpos, ypos);
rotate(angle);
text(i+" "+headline, 0, 0);
popMatrix();
}
}

PhiLho

Re: Appending XMLElement array?

2 years ago

Mmm, not sure for this one. Maybe the issue is that result is non empty, but is an array with empty (null) entries.
If you are sure of the size of the array, just use System.arraycopy to fill it.
Otherwise, I would advise to use an ArrayList, better suited for such usage.

velvetkev..

Re: Re: Appending XMLElement array?

2 years ago

Thanks phi.lho, got it to work using an ArrayList. For what it's worth, using an array, it will throw an error regardless of whether you initialise it as 0 elements or as the total size. Is this something worth raising as a bug report?

PhiLho

Re: Appending XMLElement array?

2 years ago

I don't know, it would need more tests with other kinds of objects. append() is designed to simplify usage of dynamic size arrays, particularly for arrays of primitives, at a time where autoboxing wasn't in Java. It is less interesting today, particularly to manipulate objects.