ZCW-PhoneBook/PhoneBook.java

 
import java.util.*;
/**
 * Created by leon on 1/23/18.
 */
public class PhoneBook {
    private TreeMap<String, ArrayList<String>> phoneBook;
    public PhoneBook() {
        phoneBook = new TreeMap<String, ArrayList<String>>(); 
    }
    
    public void add(String name, String phoneNumber) {
        ArrayList<String> input = phoneBook.containsKey(name) ? 
                                  phoneBook.get(name)
                                  :                         
                                  new ArrayList<String>();
        input.add(phoneNumber);
        phoneBook.put(name, input);
    }
    
    public void removeEntry(String name) {
        phoneBook.remove(name);
    }
    
    public String lookup(String name) {
        return phoneBook.get(name)
                        .toString()
                        .replaceAll("[\\[\\]]", "");
    }
    
    public String reverseLookup(String phoneNumber) {
        String output = "";
        Set<String> keys = phoneBook.keySet();
        for (String key : keys) {
            if (phoneBook.get(key).contains(phoneNumber)) {
                output = key;
            }
        }
        return output.equals("") ? "No associated name." : output;
    }
    
    public String display() {
       return phoneBook.toString().replaceAll("[{}=,]", "")
                                  .replaceAll("\\[", " - ")
                                  .replaceAll("\\]", "\n");
       
    }
    
    public TreeMap getPhoneBook() {
        return phoneBook; 
    }
}