/*************************************************************************
 *  Compilation:  javac PhoneNumber.java
 *  Execution:    java PhoneNumber
 *
 *  Implementation of a US phone number.
 *
 *************************************************************************/

import java.text.DecimalFormat;

public class PhoneNumber { 
    private String area;   // 3 digit area code
    private String exch;   // 3 digit exchange
    private String ext;    // 4 digit extension
   
    public PhoneNumber(String area, String exch, String ext) {
        this.area = area;
        this.exch = exch;
        this.ext  = ext;
    }


    // return string representation of phone number
    public String toString() {
       return "(" + area + ") " + exch + "-" + ext;
    }

    public boolean equals(Object x) {
        PhoneNumber a = this;
        PhoneNumber b = (PhoneNumber) x;
        return (a.area.equals(b.area)) &&
               (a.exch.equals(b.exch)) &&
               (a.ext.equals(b.ext));
    }


    // return same hash code as concatenating three strings together
    public int hashCode() {
        return 29791* (ext.hashCode() + 29791 * exch.hashCode()) + area.hashCode();
    }




    // test client
    public static void main(String[] args) {
        PhoneNumber a = new PhoneNumber("609", "867", "5309");
        PhoneNumber b = new PhoneNumber("609", "867", "5309");
        PhoneNumber c = new PhoneNumber("800", "867", "0000");
        System.out.println("a            " + a);
        System.out.println("b            " + b);
        System.out.println("c            " + c);
        System.out.println("a == b       " + (a == b));
        System.out.println("a.equals(b)  " + (a.equals(b)));
        System.out.println("b.equals(a)  " + (b.equals(a)));
        System.out.println("a.equals(c)  " + (a.equals(c)));
        System.out.println("a.hashCode() " + (a.hashCode()));
        System.out.println("b.hashCode() " + (b.hashCode()));
        System.out.println("c.hashCode() " + (c.hashCode()));
    }
}