java - Gurobi cannot set or print (manually) value of variables -

i'm writing program in java gurobi 6.0.2 , i've trouble management of variables, in particular can't set or print them.

example:

grbenv env = new grbenv(); grbmodel model = new grbmodel(env); grbvar x = model.addvar(0.0, grb.infinity, 0.0, grb.semiint, "x"); x.set(grb.doubleattr.x, 10.0); system.out.println(x.get(grb.doubleattr.x)); 

netbeans shows message:

exception in thread "main" gurobi.grbexception: error @ grbvar.set     @ gurobi.grbvar.set(grbvar.java:141)     @ core.optimize.main(optimize.java:29) java result: 1 

this problem happens when resolved relaxation model, can't retrive value of variables.

if want set start values variables, cannot use

x.set(grb.doubleattr.x, 10.0); 

but have write

x.set(grb.doubleattr.start, 10.0); 

getting variable values makes sense after have solved model.