제가 받은 소스에는


                        Scanner sc1=new Scanner(System.in);
                        int choice=sc1.nextInt();


                        switch(choice)
                        {
                        case 1: case 2:
                                handler.addFriend(choice);
                                break;
                        case 3:
                                handler.showAllData();


이렇게 핸들러 사용햇는데

저는 뭘 사용해야하나요