You tried to translate Arbre to Tree but forgot some occurrences...
Anyway, I think the issue is that you define a Tree in the static initialization of the class, in precedent.
Each created Tree has to create this field, so create a new Tree that need to create a new Tree, etc.
Solution, as often in recursive processes: make the creation conditional.
Perhaps something like:

1. class Tree {
2.   int page;
3.   ArrayList<Tree> next = new ArrayList<Tree>();
4.   Tree precedent;
5. 
   
6.   Tree(int p) {
7.     page = p;
8.     if (page >= 0) {
9.       precedent = new Tree(-1);
10.     }
11.   }
12. 
    
13.   void addTreeSon(Tree son) {
14.     son.precedent = this;
15.     next.add(son);
16.   }
17. 
    
18.   void addElementSon(int n) {
19.     Tree son = new Tree(n);
20.     son.precedent = this;
21.     next.add(son);
22.   }
23. }

 You tried to translate Arbre to Tree but forgot some occurrences...

You're right, as you can see, I am French :) .


I see what you mean. It works perfectly with your correction. Thank you very much !

While coding this, I was wondering if you could use pointers like you do in the C language (a pointer to the precedent or to the next tree)... (if there is no precedent or no next element, then you just assign the value NULL to the pointer)
Is there something similar in Java/Processing ?

You can't assign an explicit memory address to an Object variable in Java. However, you may assign null!
Just be aware that any instances of a class (allocated memory block) which have no variable pointing to it,
at some point, end up removed by the Java's GC (Garbage Collector)!

P.S.: Java has some very useful & exotic collections from import java.util.*;
I believe class LinkedList from there is very similar to what you are trying to accomplish?!

As said, NULL is the null keyword in Java.
If you assign an object to a variable, you actually assign the reference of the object.
All new SomeClass() create an instance in memory, and you can assign these instances to several locations, since you assign only their reference. So an object can be assigned to a variable, can be "shared" among several ArrayList or other collections, etc.
A location assigned with null indicates it has no reference to any object.