PImage = null ?

AzazelHD

I have a class Item with an attribute PImage image;

But i never create an instance of that image.

I do this for example:

class Heart extends Item{

  PImage h = loadImage("heart_pink.png");

  Heart(float x, float y){
    super(x,y);
  }

  void show() {
    image(h, x - h.width/2, y - h.height/2);
  }

And it doesnt work cuz on Item, on image i get a null pointer.

I fix it by saying: PImage image = createImage(0,0,0);

But i dont really like it since BEFORE i call that image, on heart, i loadImage.

GoToLoop

https://forum.Processing.org/two/discussion/15473/readme-how-to-format-code-and-text

Rather than loading resources in classes, prefer passing an already loaded resource to the class: *-:)

// Forum.Processing.org/two/discussion/23867/pimage-null#Item_1
// 2017-Aug-19

static final String FILENAME = "heart_pink.png";
Heart heart;

void setup() {
  heart = new Heart(width>>1, height>>1, loadImage(FILENAME));
}

class Item {
  float x, y;

  Item(float px, float py) {
    x = px;
    y = py;
  }
}

class Heart extends Item {
  PImage h;

  Heart(float x, float y, PImage img) {
    super(x, y);
    h = img;
  }
}

Chrisir

And it doesnt work cuz on Item, on image i get a null pointer.

interestingly, image h is only known in heart, not in item:

// Forum.Processing.org/two/discussion/23867/pimage-null#Item_1
// 2017-Aug-19

static final String FILENAME = "heart_pink.png";
Heart heart;
Item i;

void setup() {
  size(900, 900);
  i=new Item(2, 2); 
  heart = new Heart(width>>1, height>>1, loadImage(FILENAME));
}

void draw() {
  println(heart.h); println(i.h);
  heart.show();
}

// ======================================

class Item {

  float x, y;
  PImage h;

  Item(float px, float py) {
    x = px;
    y = py;
  }

  void show() { 
    image(h, 
      x - h.width/2, 
      y - h.height/2);
  }
}

class Heart extends Item {

  Heart(float x, float y, 
    PImage img) {

    super(x, y);
    h = img.get();
  }
}
//

AzazelHD

I have 2 classes (and i may add like 2 or 3 more) which extend from Item, so i CANT load an image on Item, cuz each class has its own image. I have a heart, spiders, i may have boomerangs and circles.

So thats why i add heart_pink only on heart class.

AzazelHD

This is my class Item (i need an image to so i can make the collide method):

class Item{

  float x;
  float y;
  PImage image;

  Item(float x, float y){
    this.x = x;
    this.y = y;
    rect(x - image.width/2, y - image.height/2, image.width, image.height);
  }

  boolean collide(Item other){
  return (x < other.x + other.image.width &&
     x + this.image.width > other.x &&
     y < other.y + other.image.height &&
     this.image.height + y > other.y);
  }
}

This is the heart constructor:

class Heart extends Item{

  PImage h = loadImage("heart_pink.png");

  Heart(float x, float y){
    super(x,y);
  }

  void show() {
    image(h, x - h.width/2, y - h.height/2);
  }

And this is the Enemy constructor:

class Enemy extends Item{

  float speed;
  PImage s = loadImage("spider.png");

  Enemy(float x, float y){
    super(x,y);
    speed = random(-4,-3);
  }

As u see, each class take its own image before building the object. So i dont know why i get a null pointer on Item.

AzazelHD

And sorry, idk how to write code format here

Chrisir

See link by gotoloop above

AzazelHD

okey, done ^^