Hello,

I am new to using processing and I don't understand the errors that I am getting. Is there a list somewhere that has a breakdown of what the likely causes of error messages are?

specifically the error is a nullpointerexception in the following code


/* Reads values from a text file*/
//size(800,1000);

// load text file
String[]  tags= loadStrings("tag.txt");
String[] weights = loadStrings("weights3.txt");
// convert strings to numbers
int[] tag = int(tags);
int[] weight = int(weights);
int j = 0;

void setup() {
 size(800,400);
 background(255);
 smooth();
}
void draw() {
// For every value draw an ellipse
for (int i = 0; i < tag.length; i++) {
 j=j+tag[i];
 ellipseMode(CENTER);
 fill( weight[i],  tag[i]/weight[i], tag[i], 255);//(tag[i], tag[i], tag[i], 100)
 ellipse(width/2, j, weight[i] , tag[i]); //(width/2,j, weight[i], tag[i])
}
}

thanks very much

Hi, just have the same problem trying to open the txt file before the setup function working a another project. After cut & pasting the text file's operation in draw everething works. I'ven't test your code but i think i'd work like that.

jared,

you probably want to do the loading in setup not draw, as it only needs to happen once I assume.

something like this should work (and be a little more efficient.)

Code:

// load text files 

// these variables have global scope
int[] tag, weight;

void setup() {
  size(800,400);
  background(255);
  smooth();
  // you can combine loading and casting in one expression
  tag = int(loadStrings("tag.txt"));
  weight = int(loadStrings("weights3.txt"));
}

void draw() {  
  // For every value draw an ellipse
  for (int i=0, j=0; i<tag.length; i++) {
    fill(weight[i],  tag[i]/weight[i], tag[i], 255);
    ellipse(width/2, j, weight[i], tag[i]);
    j+=tag[i];
  }
} 


 

*** I modifed this. I noticed you weren't reinitializing j, so I declared it in for loop head.