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// Making PhoneNumber comparable - Pages 65-66

import java.util.*;

public final class PhoneNumber implements Cloneable, Comparable<PhoneNumber> {

private final short areaCode;

private final short prefix;

private final short lineNumber;

public PhoneNumber(int areaCode, int prefix,

int lineNumber) {

rangeCheck(areaCode, 999, "area code");

rangeCheck(prefix, 999, "prefix");

rangeCheck(lineNumber, 9999, "line number");

this.areaCode = (short) areaCode;

this.prefix = (short) prefix;

this.lineNumber = (short) lineNumber;

}

private static void rangeCheck(int arg, int max,

String name) {

if (arg < 0 || arg > max)

throw new IllegalArgumentException(name +": " + arg);

}

@Override public boolean equals(Object o) {

if (o == this)

return true;

if (!(o instanceof PhoneNumber))

return false;

PhoneNumber pn = (PhoneNumber)o;

return pn.lineNumber == lineNumber

&& pn.prefix == prefix

&& pn.areaCode == areaCode;

}

@Override public int hashCode() {

int result = 17;

result = 31 * result + areaCode;

result = 31 * result + prefix;

result = 31 * result + lineNumber;

return result;

}

/**

* Returns the string representation of this phone number.

* The string consists of fourteen characters whose format

* is "(XXX) YYY-ZZZZ", where XXX is the area code, YYY is

* the prefix, and ZZZZ is the line number. (Each of the

* capital letters represents a single decimal digit.)

*

* If any of the three parts of this phone number is too small

* to fill up its field, the field is padded with leading zeros.

* For example, if the value of the line number is 123, the last

* four characters of the string representation will be "0123".

*

* Note that there is a single space separating the closing

* parenthesis after the area code from the first digit of the

* prefix.

*/

@Override public String toString() {

return String.format("(%03d) %03d-%04d",

areaCode, prefix, lineNumber);

}

@Override public PhoneNumber clone() {

try {

return (PhoneNumber) super.clone();

} catch(CloneNotSupportedException e) {

throw new AssertionError(); // Can't happen

}

}

// Works fine, but can be made faster

// public int compareTo(PhoneNumber pn) {

// // Compare area codes

// if (areaCode < pn.areaCode)

// return -1;

// if (areaCode > pn.areaCode)

// return 1;

//

// // Area codes are equal, compare prefixes

// if (prefix < pn.prefix)

// return -1;

// if (prefix > pn.prefix)

// return 1;

//

// // Area codes and prefixes are equal, compare line numbers

// if (lineNumber < pn.lineNumber)

// return -1;

// if (lineNumber > pn.lineNumber)

// return 1;

//

// return 0; // All fields are equal

// }

public int compareTo(PhoneNumber pn) {

// Compare area codes

int areaCodeDiff = areaCode - pn.areaCode;

if (areaCodeDiff != 0)

return areaCodeDiff;

// Area codes are equal, compare prefixes

int prefixDiff = prefix - pn.prefix;

if (prefixDiff != 0)

return prefixDiff;

// Area codes and prefixes are equal, compare line numbers

return lineNumber - pn.lineNumber;

}

public static void main(String[] args) {

NavigableSet<PhoneNumber> s = new TreeSet<PhoneNumber>();

for (int i = 0; i < 10; i++)

s.add(randomPhoneNumber());

System.out.println(s);

}

private static final Random rnd = new Random();

private static PhoneNumber randomPhoneNumber() {

return new PhoneNumber((short) rnd.nextInt(1000),

(short) rnd.nextInt(1000),

(short) rnd.nextInt(10000));

}

}