private void UpdateListItems()//dependent on viewMode
        {
            switch (ViewMode)
            {
            case mode.exercise:
                exercises        = MyDatabase.GetAllExercises();
                listView.Adapter = new TrainingScreenAdapter <Exercise>(this, exercises);
                break;

            case mode.training:
                trainings        = MyDatabase.GetAllTrainings();
                listView.Adapter = new TrainingScreenAdapter <Training>(this, trainings);
                break;

            case mode.plan:
                plans            = MyDatabase.GetAllPlans();
                listView.Adapter = new TrainingScreenAdapter <Plan>(this, plans);
                break;
            }
        }