System.out.println("1");
    cplex = new IloCplex();
    System.out.println("2");
    IloIntVar z = cplex.intVar(0, Integer.MAX_VALUE, "z");
    IloIntVar[] x = new IloIntVar[hotels.size()];
    IloIntVar[][] y = new IloIntVar[maxNumberOfRooms][hotels.size()];
    IloIntVar[][] g = new IloIntVar[maxNumberOfRooms][hotels.size()];
    IloLinearNumExpr linearNumExpr2 = cplex.linearNumExpr();
    IloLinearNumExpr linearNumExpr4 = cplex.linearNumExpr();
    IloLinearIntExpr linearIntExpr = cplex.linearIntExpr();
    IloLinearNumExpr objective = cplex.linearNumExpr();
    List<IloRange> constraints = new ArrayList<>();
    IloIntExpr[] intExprs = new IloIntExpr[hotels.size()];
    List<HashMap<String, Object>> hotelRooms = new LinkedList<>();
    double newScalarProduct = 0.0;
    double yMax = days;
    double yMin = 0.1;

    for (int i = 0; i < hotels.size(); ++i) {
        IloLinearNumExpr linearNumExpr1 = cplex.linearNumExpr();
        IloLinearNumExpr linearNumExpr3 = cplex.linearNumExpr();
        x[i] = cplex.intVar(0, Integer.MAX_VALUE, ("x" + i));
        linearIntExpr.addTerm(1, x[i]);

        for (int j = 0; j < maxNumberOfRooms; ++j) {
            y[j][i] = cplex.intVar(0, days, ("y" + j + i));
            g[j][i] = cplex.intVar(0, 1, ("g" + j + i));
            linearNumExpr1.addTerm(pricePerNight[j][i], y[j][i]);
            linearNumExpr3.addTerm(places[j][i], g[j][i]);
        }

        objective.addTerm(certainties.get(i), x[i]);
        linearNumExpr2.add(linearNumExpr1);
        linearNumExpr4.add(linearNumExpr3);
    }

    for (int i = 0; i < hotels.size(); ++i) {
        IloLinearIntExpr linearIntExpr1 = cplex.linearIntExpr();

        for (int j = 0; j < maxNumberOfRooms; ++j) {
            linearIntExpr1.addTerm(1, y[j][i]);
            constraints.add((IloRange) cplex.addGe(y[j][i], cplex.prod(yMin, g[j][i])));
            constraints.add((IloRange) cplex.addLe(y[j][i], cplex.prod(yMax, g[j][i])));
        }

        intExprs[i] = cplex.abs(cplex.diff(x[i], 1));
        constraints.add((IloRange)cplex.addEq(linearIntExpr1, x[i]));
    }

    for (Double scalarProduct : solToDiscard) {
        IloLinearNumExpr linearNumExpr_ = cplex.linearNumExpr();
        linearNumExpr_.addTerms(coefficients, x);
        constraints.add(cplex.addGe(cplex.abs(cplex.diff(linearNumExpr_, scalarProduct)), 0.001));
    }

    constraints.add((IloRange)cplex.addEq(cplex.sum(intExprs), z));
    constraints.add(cplex.addLe(linearIntExpr, days));
    constraints.add(cplex.addLe(linearNumExpr2, budget));
    constraints.add(cplex.addGe(linearNumExpr4, numPeople));
    cplex.addMaximize(cplex.diff(objective, z));

    System.out.println("3");
    if (cplex.solve()) {
        System.out.println("8");
        int realDays = 0;
        for (int j = 0; j  < hotels.size(); ++j) {
            realDays += cplex.getValue(x[j]);
            System.out.println("5");
            for (int i = 0; i < maxNumberOfRooms; ++i) {
                if (cplex.getValue(y[i][j]) > 0) {
                    HashMap<String, Object> hm = new HashMap<String, Object>();
                    hm.put("Room", hotelsRooms.get(hotels.get(j).getId()).get(i));
                    hm.put("DaysInRoom", cplex.getValue(y[i][j]));
                    System.out.println("y" + i + j + " :" + cplex.getValue(y[i][j]));
                    hotelRooms.add(hm);
                }
            }
        }​

Clearly it prints the 3, but it doesn't prints the 8... I also tried to increase the heap dedicated to the process, but nothing ...