@Override
    public boolean equals(Object obj){
        if (obj instanceof Noeud){
            Noeud noeud = (Noeud) obj;
            return (noeud.id == this.id) && (noeud.xMetre==this.xMetre)  && (noeud.yMetre == this.yMetre);
        }
        else { 
            return false;
        }
    }