Hi! I am working with processing using the eclipse IDE and my idea is to have a main class that extends PApplet and have some separate classes for the main to work with.
 Some classes should have drawing methods but as they don't extend PApplet I don't have access to the primitive methods like rect() or even print().

 How should I organize my code so I can acess these methods from classes outside the main like I do with the processing IDE?
The program will be just too big to put it all together in one file.

you need to pass a reference of the PApplet extended class to your custom class.

(1) you can pass a reference of PApplet to your custom classes in the constructor for example. in setup of your PApplet extended class try this:
Code:

MyClass m;

void setup() {
  m = new MyClass(this);
}

void draw() {
  m.update();
}

 

then in MyClass
Code:

public class MyClass {
  PApplet myPApplet;
  public MyClass(PApplet thePApplet) {
    myPApplet = thePApplet;
  }

  public void update() {
    myPApplet.rect(0,0,10,10);
  }

}
 

or

(2) you pass a reference to PApplet when you update your class, for example:
in your PApplet extended class

Code:

void draw() {
  m.draw(this);
}
 

in your MyClass you would need a method draw(PApplet) then
Code:

public void draw(PApplet thePApplet) {
  thePApplet.rect(0,0,10,10);
}
 

hope this helps. best,
andi