Create a two dimensional array from XML file.

Alexandros

Hello,

I have the following XML code:

<?xml version="1.0"?>
<data type="artists">
    <artist name="Astroid Power Up">
        <album>Google Plex</album>
    </artist>
    <artist name="Battles">
        <album>Gloss Drop</album>
        <album>La Di Da Di</album>
    </artist>
    <artist name="Brad Mehldau">
        <album>Day is Done</album>
        <album>House on Hill</album>
        <album>Largo</album>
        <album>Modern Music</album>
    </artist>
    <artist name="Bugge Wesseltoft">
        <album>Trialogue</album>
    </artist>
    <artist name="David Sylvian">
        <album>Gone to Earth</album>
    </artist>
</data>

and I want to create an Array of the kind: artist[artistName][albumsByArtist]. For example, artist[0][0] = "Battles" artist[0][1] = "Gloss Drop" artist[0][2] = "La Di Da Di" (another more optimal structure suggestion would be welcome)

I made an Array containing the artist name, and for each artist, an Array with each oh his/her albums. I can't find a way to associate the artist with the albums though.

XML data;
String[] artists;

void setup() {
  data = loadXML("data.xml");
  artists = new String[0];

  for (XML artist : data.getChildren("artist")) {
    String n = artist.getString("name");
    artists = append(artists, n); // set name to first element of array

    String[] albumsByArtist = new String[0];

    for (XML album : artist.getChildren("album")) {
      String a = album.getContent();
      albumsByArtist = append(albumsByArtist, a); // fill albumsByArtist with albums names
    }
  }
}

Chrisir

Tricky

Line 2 should be 2D as in [][]

Line 12 should be obsolete

But there are a few details there.... tricky

It's always hard when you use append

Instead declare the thing in line 6 with the correct length of the array

Chrisir

apart from a 2D array I could imagine a class artist that holds the artist name plus other data about him or her plus an ArrayList for the Albums (of class Album with other data on it)

also, look ar hashMap which allows you to look up artists/Strings more easily

here is the 2D array:

XML data;
String[][] artists;

void setup() {

  size(1200, 800); 
  data = loadXML("data.xml");

  int lengthOfArray = data.getChildren("artist").length; 
  artists = new String[lengthOfArray][1];

  int i=0; 
  for (XML artist : data.getChildren("artist")) {

    // get the name and store it at pos 0 
    String n = artist.getString("name");
    artists[i][0]  = n; // set name to first element of array

    for (XML album : artist.getChildren("album")) {
      String a = album.getContent();
      // we use append to lengthen this line in the 2D-array  
      artists[i] = (String[]) append(artists[i], a); // fill with albums names
    }//for
    i++;
  }//for
  background(0);
}

void draw() {
  //
  background(0);

  // loop 
  for (int i=0; i<artists.length; i++) {

    // header 
    fill(255, 2, 2); // red
    text(artists[i][0], i*144+66, 30);

    // rest of column 
    fill(255); // white 
    for (int iy=1; iy<artists[i].length; iy++) {
      text(artists[i][iy], i*144+66, iy*30+22);
    }
  }
}

Alexandros

Thanks!

I created an Artist class after all, it was simpler and perhaps more efficient. In your example, I am not sure I understand this line you used to fill the album names in the second dimension: artists[i] = (String[]) append(artists[i], a);

Chrisir

artists[i] = (String[]) append(artists[i], a);

yeah, read the reference on append

we need to help (cast) append to know what type it is giving out as a result, therefore we need to say (String[])

also, since it is a 2D array, artists[i] is referring to one array, namely the 2nd dimension of the array

please note that the arrays artists[0] and artists[1] and artists[2].... are of different length, depending on the number of albums

So it is not a rectangular grid but more lines (arrays) of different length in the main (first) array

In java a 2D array is an array of arrays basically