How to use setvalue?

Hi Im new on vaadin and have a doubt on how the setvalue works for the diferent components?, basically I have this:

public void setFieldsValues(User usr) {
this.getField(“username”).setValue( usr.getUsername() );
this.getField(“idperson”).setValue( usr.getIdperson());
this.getField(“rolename”).setValue( usr.getRolename());
this.getField(“isactive”).setValue( usr.getIsactive());

I call this functions but the data on the class usr is not loaded on the form user that have those fields beeing idperson and rolename combos and isactive a checkbox. Why this dont work?