[java][Hashtable를 사용한 전화번호부]

import java.util.*; import java.io.*; public class PhoneBook { private Hashtable phoneBook; public PhoneBook(){ this.phoneBook = new Hashtable(); } public void add(String name, String number){ if (this.phoneBook.containsKey(name) ){ System.out.println("이름"+ name +"이 전화번호부에 있습니다."); } else{ this.phoneBook.put(name,number); System.out.println("이름"+ name +"을 전화번호부에 추가하였습니다."); } } public void find(String name){ if(this.phoneBook.containsKey(name)){ String number=this...