Горячее преобразование списка из карты в другой список

Question

for(Student student : studentList){ 
    if(studentsList.containsKey(student.getGrade())){ 
        List<Student> currentList = new LinkedList<Student>(); 
        /* I want to take the list from the map and the to add() another student, 
           after that to -> studentsList.put(student.getGrade(),currentList);
        */ 

    }else{ 
        List<Student> newStudentList = new LinkedList<Student>(); 
        newStudentList.add(student); 
        studentsList.put(student.getGrade(), newStudentList);
    }
}