NullPointerException Processing 3.0

Question

I've been coding for a few weeks now and I'm stuck on this null pointer exception.

It gives me the following error:

java.lang.NullPointerException  
at processing.core.PGraphics.image(PGraphics.java:3768)     
at processing.core.PApplet.image(PApplet.java:12175)    
at beginfase.tekenBeginscherm(beginfase.java:126)   
at beginfase.draw(beginfase.java:51)    
at processing.core.PApplet.handleDraw(PApplet.java:2412)    
at processing.awt.PSurfaceAWT$12.callDraw(PSurfaceAWT.java:1540)    
at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:316)

it marks this line of code: image(kaarten[r],50,50);

   String[] kaart = { 
"Aclubs.png", 
"2clubs.png", 
"3clubs.png",
"4clubs.png",
"5clubs.png",
"6clubs.png",
"7clubs.png",
"8clubs.png",
"9clubs.png",
"10clubs.png",
"Jclubs.png",
"Qclubs.png",
"Kclubs.png",
};

PImage[] kaarten = new PImage [kaart.length];

void settings() {
  size(round(displayWidth * 0.9), round(displayHeight * 0.9));
}

void setup() {
  laadBeginscherm();
 // schudKaarten();
 }



void draw() {
  tekenBeginscherm();
 // schudKaarten();
  // println(mouseX);
  //println(mouseY);
}

There is a bit of my code I know it's probably a mess and really bad, but I can't find what the nullpointerexception error is. Please help.

Yes, i now added the 10clubs.png

This is the code I use to load the image.

if (scherm == 3) {
        background(0, 148, 0);
        for (int g = 0; g < 12000; g = g+round((displayWidth * 0.9))/12) {
          int r = int (random(kaarten.length));
          println(r);
          image(kaarten[r],g+25,50);
        }      
      }

EDIT: Okay i made a smaller (mini) version of the error. It uses just 1 card but that's just for the example of it, so you can add a .png yourself

    String[] kaart = { 
  "Aclubs.png", 
};


PImage[] kaarten = new PImage [kaart.length];

void setup() {
  kaart = loadImage("Aclubs.png");
}

void draw() {
  tekenBeginscherm();
}
void tekenBeginscherm() {
  if (keyPressed == true ) {
    background(0, 148, 0);
    for (int g = 0; g < 12000; g = g+round((displayWidth * 0.9))/12) {
      int r = int (random(kaarten.length));
      println(r);
      image(kaarten[r], 50, 50);
    }
  }
}

If I try to add this: kaart = loadImage("Aclubs.png"); in setup() The program will give me this error instead:

Type mismatch, "processing.core.PImage" does not match with "java.lang.String[]"

Answer 1

When loading an image, you have to make sure of a few things:

• Make sure your image files have been added to your sketch. They should be inside a data directory inside your sketch folder. Make sure they're spelled correctly.

• Make sure you're calling the loadImage() function before trying to call the image() function.

From the reference, here is a small example that shows how to load and display an image:

PImage img;

void setup() {
  img = loadImage("laDefense.jpg");
}

void draw() {
  image(img, 0, 0);
}

My guess is that you forgot to call loadImage(), which means that your image variable (in your case, array index) is null, which will cause a NullPointerException when you call the image() function.

If you're still having trouble, please narrow your problem down to a small example like this one.

Edit: In response to your edited question:

If I try to add this: kaart = loadImage("Aclubs.png"); in setup() The program will give me this error instead:

Type mismatch, "processing.core.PImage" does not match with "java.lang.String[]"

You need to loop over every index in your array and call loadImage() to load an image into each index.