Java Code: URL Shortener

Wrote this code some time back for a programming interview, sharing it for everyone's use.
Its a 64 character encoded URL shortener code written in java. The code does not use any database backend but can be easily modified to support that.

Update: replacing the code text with Github Gist for better formatting support

	package testjava;
	import java.util.HashMap;
	import java.util.Random;
	/*
	* URL Shortener
	*/
	public class URLShortener {
	// storage for generated keys
	private HashMap<String, String> keyMap; // key-url map
	private HashMap<String, String> valueMap;// url-key map to quickly check
	// whether an url is
	// already entered in our system
	private String domain; // Use this attribute to generate urls for a custom
	// domain name defaults to http://fkt.in
	private char myChars[]; // This array is used for character to number
	// mapping
	private Random myRand; // Random object used to generate random integers
	private int keyLength; // the key length in URL defaults to 8
	// Default Constructor
	URLShortener() {
	keyMap = new HashMap<String, String>();
	valueMap = new HashMap<String, String>();
	myRand = new Random();
	keyLength = 8;
	myChars = new char[62];
	for (int i = 0; i < 62; i++) {
	int j = 0;
	if (i < 10) {
	j = i + 48;
	} else if (i > 9 && i <= 35) {
	j = i + 55;
	} else {
	j = i + 61;
	}
	myChars[i] = (char) j;
	}
	domain = "http://fkt.in";
	}
	// Constructor which enables you to define tiny URL key length and base URL
	// name
	URLShortener(int length, String newDomain) {
	this();
	this.keyLength = length;
	if (!newDomain.isEmpty()) {
	newDomain = sanitizeURL(newDomain);
	domain = newDomain;
	}
	}
	// shortenURL
	// the public method which can be called to shorten a given URL
	public String shortenURL(String longURL) {
	String shortURL = "";
	if (validateURL(longURL)) {
	longURL = sanitizeURL(longURL);
	if (valueMap.containsKey(longURL)) {
	shortURL = domain + "/" + valueMap.get(longURL);
	} else {
	shortURL = domain + "/" + getKey(longURL);
	}
	}
	// add http part
	return shortURL;
	}
	// expandURL
	// public method which returns back the original URL given the shortened url
	public String expandURL(String shortURL) {
	String longURL = "";
	String key = shortURL.substring(domain.length() + 1);
	longURL = keyMap.get(key);
	return longURL;
	}
	// Validate URL
	// not implemented, but should be implemented to check whether the given URL
	// is valid or not
	boolean validateURL(String url) {
	return true;
	}
	// sanitizeURL
	// This method should take care various issues with a valid url
	// e.g. www.google.com,www.google.com/, http://www.google.com,
	// http://www.google.com/
	// all the above URL should point to same shortened URL
	// There could be several other cases like these.
	String sanitizeURL(String url) {
	if (url.substring(0, 7).equals("http://"))
	url = url.substring(7);
	if (url.substring(0, 8).equals("https://"))
	url = url.substring(8);
	if (url.charAt(url.length() - 1) == '/')
	url = url.substring(0, url.length() - 1);
	return url;
	}
	/*
	* Get Key method
	*/
	private String getKey(String longURL) {
	String key;
	key = generateKey();
	keyMap.put(key, longURL);
	valueMap.put(longURL, key);
	return key;
	}
	// generateKey
	private String generateKey() {
	String key = "";
	boolean flag = true;
	while (flag) {
	key = "";
	for (int i = 0; i <= keyLength; i++) {
	key += myChars[myRand.nextInt(62)];
	}
	// System.out.println("Iteration: "+ counter + "Key: "+ key);
	if (!keyMap.containsKey(key)) {
	flag = false;
	}
	}
	return key;
	}
	// test the code
	public static void main(String args[]) {
	URLShortener u = new URLShortener(5, "www.tinyurl.com/");
	String urls[] = { "www.google.com/", "www.google.com",
	"http://www.yahoo.com", "www.yahoo.com/", "www.amazon.com",
	"www.amazon.com/page1.php", "www.amazon.com/page2.php",
	"www.flipkart.in", "www.rediff.com", "www.techmeme.com",
	"www.techcrunch.com", "www.lifehacker.com", "www.icicibank.com" };
	for (int i = 0; i < urls.length; i++) {
	System.out.println("URL:" + urls[i] + "\tTiny: "
	+ u.shortenURL(urls[i]) + "\tExpanded: "
	+ u.expandURL(u.shortenURL(urls[i])));
	}
	}
	}

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