Copy part of a ParticleSystem (Tree shaped)

PAk

Hello. I am creating an app where I use an own modified version of Traer Physics library, hence a ParticleSystem with many nodes. The modifications I have made to the Node class were adding a unique PID, the parent_ID and a children arraylist.

I have also implemented functions for erasing, adding, editing and even moving nodes (particles), however copying is being quite difficult for me, since every thing I try, makes a shallow copy of the nodes (and I would need a unique_id per node).

How could I implement that functionality? The class ParticleSystem just uses arraylists of other classes as Particles (node), attraction, etc. //package traer.physics; //import java.util.*; public class ParticleSystem { public static final int RUNGE_KUTTA = 0; public static final int MODIFIED_EULER = 1; protected static final float DEFAULT_GRAVITY = 0;//1.0f; //0; protected static final float DEFAULT_DRAG = 0.001f; ArrayList particles = new ArrayList(); ArrayList springs = new ArrayList(); ArrayList attractions = new ArrayList(); ArrayList customForces = new ArrayList(); ArrayList pulses = new ArrayList(); Integrator integrator; PVector gravity = new PVector(); ...

To make clear my architecture, I post a snapshot of it:

Thank you