public void sortGpa() {
		// Cach 1: Khai báo bình thường
		Collections.sort(studentlist, new Comparator<StudentModel>() {

			@Override
			public int compare(StudentModel o1, StudentModel o2) {
				if (o1.getGpa() < o2.getGpa()) return -1;
				return 1;
			}
		});

		// Cach 2: khai báo cấu trúc rút gọn
		Collections.sort(studentlist, (o1, o2) -> {
			if (o1.getGpa() < o2.getGpa())
				return -1;
			return 1;
		});
		studentlist.forEach((list) -> {
			list.display();
		});
	}

	public void sortName() {
//Khai báo kiểu bình thường
		Collections.sort(studentlist, new Comparator<StudentModel>() {

			@Override
			public int compare(StudentModel o1, StudentModel o2) {
				return o1.getName().compareTo(o2.getName());
			}
		});
//Khai báo kiểu rút gọn
		Collections.sort(studentlist, (o1, o2) -> o1.getName().compareTo(o2.getName()));
		studentlist.forEach((list) -> {
			list.display();
		});
	}