private List<String> getTeacherFromList()
	{
		List<String> teachers_list = new ArrayList<String>();
		int size = list.getModel().getSize();
			for(int i=0; i < size; i++)
			{
				String teacher_name = ((Group_schedule)list.getModel().getElementAt(i)).getTeacher().getName();
				if(!teachers_list.contains(teacher_name))
				{
					teachers_list.add(teacher_name);
				}
			}
			//this.teacher_list = teachers_list;
		return teachers_list;
	}