java - Gurobi can't add constraints -

i'm writing program in java solve mip problem gurobi. problem requires lot of constraints , variables first ones cannot added model. deeper in problem, when try add constraint model show it(read through debugging),but row_no equal -1. first things first:

• create multi-dimensional matrix of variables:

      grbvar[][] x = new grbvar[imax][jmax];     (int = 0; < imax; i++) {         (int j = 0; j < jmax; j++) {             x[i][j] = model.addvar(0.0, grb.infinity, 0.0, grb.semiint, "xi" + + "j" + j);         }     } 

• add constraints (looks xij < 10):

      (int = 0; < imax; i++) {         (int j = 0; j < jmax; j++) {              grblinexpr lhs = new grblinexpr();             grblinexpr rhs = new grblinexpr();              lhs.addterm(1.0, x[i][j]]);             rhs.addconstant(10);              model.addconstr(lhs, grb.less_equal, rhs, "vi" + + "j" + j);         }     } 

• debug project: there imax * jmax columns, imax * jmax variables, imax * jmax contraints (with row_no = -1) , 0 rows.

any idea?

edit

i'm not use of row_no, suppose gurobi (from abstract point of view) organizes data pseudo-matrix variables stored columns , constraints rows. why that? because every times add variable counter of columns grow 1 , col_no associated particular column, instead when add constraint counter of rows doesn't change.

columns: http://www.gurobi.com/documentation/6.0/refman/java_grbmodel_getcol.html rows:http://www.gurobi.com/documentation/6.0/refman/java_grbmodel_getrow.html

edit 2

i don't have problems columns, rows or else, when try solve relaxed model, gurobi shows output:

optimize model 0 rows, 1475400 columns , 0 nonzeros coefficient statistics:   matrix range    [0e+00, 0e+00]   objective range [0e+00, 0e+00]   bounds range    [1e+00, 1e+03]   rhs range       [0e+00, 0e+00] presolve removed 0 rows , 1475400 columns presolve time: 0.36s presolve: rows , columns removed iteration    objective       primal inf.    dual inf.      time        0    0.0000000e+00   0.000000e+00   0.000000e+00      1s  solved in 0 iterations , 0.72 seconds optimal objective  0.000000000e+00 

the solution feasible, can't show useful information. tought should update model after adding variables, not constraints. additionaly, read gurobi documentation if model needs update throws exception (not case):

"the common symptom of missing update not_in_model exception, indicates object trying reference isn't in model yet"

edit 3

i've followed suggest of update model (after adding constraints) , everythings works correctly. supposed wasn't mandatory but, in contrast of documentation (and code examples), is.

i guess model shows strange behaviour because variables have 0.0 coefficient in objective function. furthermore, setting variables 0 feasible solution.

while cannot explain internal mechanism of gurobi setting rows zero, gives correct answer (strange kind of) model.