@Override
 public Object getValueAt(int RowIndex, int ColumnIndex) {
   ModelStudent student = studentList.get(RowIndex);
   ModelGroup group = Logic.getInstance().loadGroup(student.getGroupId());
   switch (ColumnIndex) {
     case 0:
       return student.getName();
     case 1:
       return student.getSurname();
     case 2:
       return student.getSecondname();
     case 3:
       return student.getBirthdata();
     case 4:
       if (group != null) {
         return group.getNumber();
       } else {
         return "None";
       }
     case 5:
       return student.getId();
   }
   return null;
 }
  public StudentTableAdapter() {

    this.studentList = Logic.getInstance().loadAllStudent();
  }