Classwork:
Write a telephone lookup program, TelephoneDirectory_YI.java. Create a class Telephone with two instance fields, number and name. You have the choice of creating your own data or using the data below to create an array of 100 Telephone objects in random order. TelephoneDirectory handles lookups by name and also reverse lookups by phone number. Use a binary search for both lookups. Make sure you include the test/driver class with enough activity to show your work.
NOTE: create a text file with random data in the following format:
Last name, First name, area code "-" exchange "-" extension
The following java program might help you with “some” of the code you need to create the text data file.
/******************************************************************************
* Compilation: javac PhoneNumber.java
* Execution: java PhoneNumber
* Dependencies:
*
* Immutable data type for US phone numbers.
*
******************************************************************************/
import java.util.HashSet;
/**
* The {@code PhoneNumber} class is an immutable data type to encapsulate a
* U.S. phone number with an area @code (3 digits), exchange (3 digits),
* and extension (4 digits).
*
* For additional documentation,
* see Section 1.2 of
* Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.
*
* @author Robert Sedgewick
* @author Kevin Wayne
*/
public final class PhoneNumber {
private final int area; // area @code (3 digits)
private final int exch; // exchange (3 digits)
private final int ext; // extension (4 digits)
/**
* Initializes a new phone number.
*
* @param area the area @code (3 digits)
* @param exch the exchange (3 digits)
* @param ext the extension (4 digits)
*/
public PhoneNumber(int area, int exch, int ext) {
this.area = area;
this.exch = exch;
this.ext = ext;
}
/**
* Compares this phone number to the specified phone number.
*
* @param other the other phone number
* @return {@code true} if this phone number equals {@code other};
* {@code false} otherwise
*/
@Override
public boolean equals(Object other) {
if (other == this) return true;
if (other == null) return false;
if (other.getClass() != this.getClass()) return false;
PhoneNumber that = (PhoneNumber) other;
return (this.area == that.area) && (this.exch == that.exch) && (this.ext == that.ext);
}
/**
* Returns a string representation of this phone number.
*
* @return a string representation of this phone number
*/
@Override
public String toString() {
// 0 for padding with digits with leading 0s
return String.format(“(%03d) %03d-%04d”, area, exch, ext);
}
/**
* Returns an integer hash code for this phone number.
*
* @return an integer hash code for this phone number
*/
@Override
public int hashCode() {
return 31 * (area + 31 * exch) + ext;
}
/**
* Unit tests the {@code PhoneNumber} data type.
*
* @param args the command-line arguments
*/
public static void main(String[] args) {
PhoneNumber a = new PhoneNumber(609, 258, 4455);
PhoneNumber b = new PhoneNumber(609, 876, 5309);
PhoneNumber c = new PhoneNumber(609, 555, 5309);
PhoneNumber d = new PhoneNumber(215, 876, 5309);
PhoneNumber e = new PhoneNumber(609, 876, 5309);
StdOut.println(“a = ” + a);
StdOut.println(“b = ” + b);
StdOut.println(“c = ” + c);
StdOut.println(“d = ” + d);
StdOut.println(“e = ” + e);
HashSet
set.add(a);
set.add(b);
set.add(c);
StdOut.println(“Added a, b, and c”);
StdOut.println(“contains a: ” + set.contains(a));
StdOut.println(“contains b: ” + set.contains(b));
StdOut.println(“contains c: ” + set.contains(c));
StdOut.println(“contains d: ” + set.contains(d));
StdOut.println(“contains e: ” + set.contains(e));
StdOut.println(“b == e: ” + (b == e));
StdOut.println(“b.equals(e): ” + (b.equals(e)));
}
}
From Ashwin:
