ZCW-PhoneBook/PhoneBook.java

import java.util.*;

/**
 * Created by leon on 1/23/18.
 */
public class PhoneBook {
    private String name, phoneNumber;
    private Map<String, String> entries;

    public PhoneBook(){
        this.entries = new TreeMap<String, String> ();
    }

    public void add(String name, String phoneNumber){
        this.entries.put(name, phoneNumber);

    }

    public void remove(String name){
        this.entries.remove(name);
    }


    public void display(){

        if (this.entries.isEmpty()) System.out.println("Empty");

        for (Map.Entry<String,String> entry : entries.entrySet()){
            String key = entry.getKey();
            String value = entry.getValue();

            System.out.println(key + " " + value);
        }

    }

    
}