import java.util.*;public class Name implements Comparable {    private String  firstName, lastName;    public Name(String firstName, String lastName) {        if (firstName==null || lastName==null)            throw new NullPointerException();        this.firstName = firstName;        this.lastName = lastName;    }    public String firstName()    {return firstName;}    public String lastName()     {return lastName;}    public boolean equals(Object o) {        if (!(o instanceof Name))            return false;        Name n = (Name)o;        return n.firstName.equals(firstName) &&               n.lastName.equals(lastName);    }    public int hashCode() {        return 31*firstName.hashCode() + lastName.hashCode();    }    public String toString() {return firstName + " " + lastName;}    public int compareTo(Object o) {        Name n = (Name)o;        int lastCmp = lastName.compareTo(n.lastName);        return (lastCmp!=0 ? lastCmp :                firstName.compareTo(n.firstName));    }}