import java.util.*;
import java.io.*;

public class PhoneRegister {
    private HashMap<String, Integer> reg; // the register

    /**
     *  Construct an empty register.
     */
    public PhoneRegister() {
    	reg = new HashMap<String, Integer>();
    }
   
    /**
     * Add a name and a corresponding number to the register.
     * If element with same name is present its number is
     * updated to nbr.
     */
    public void add(String name, int nbr) {
    	reg.put(name, nbr);
    }

    /**
     * Search for number belonging to name.
     * If no such element in register return number < 0.
     */
    public int findNbr(String name) {
    	if(!reg.containsKey(name))
    		return -1;
    	
    	return reg.get(name);
    }
    
    /** 
     * Remove element with the the specified name.
     * If no such element in register return false, otherwise true.
     */
    public boolean remove(String name) {
    	if(!reg.containsKey(name))
    		return false;
    		
    	reg.remove(name);
    	return true;
    }

    /**
     * Test if register is empty.
     */
    public boolean isEmpty() {
    	return reg.isEmpty();
    }

    /**
     * Print a table of names and numbers in alphbetical order.
     */
    public void print() {
    	TreeMap myTreeMap = new TreeMap(reg);
    	
		while(!myTreeMap.isEmpty()) {
			// Visa det första elementet
			System.out.println("Namn: " + myTreeMap.firstKey() + " \t\t Telefonnummer: " + myTreeMap.get(myTreeMap.firstKey()));
			// Ta bort det första elementet
			myTreeMap.remove(myTreeMap.firstKey());
		}
    }
}