Shortener.java

/**
 * Shortener encodes numbers to base 36 to create a shortened link like flic.kr.
 * 
 * @author		Edward Y. Chen
 * @since		01/16/2013 
 */

package edu.mssm.pharm.maayanlab.Enrichr;

public class Shortener {

	private static final String alphabet = "0123456789abcdefghijklmnopqrstuvwxyz";
	private static final int base = 36;
	
	public static String encode(int number) {
		StringBuilder linkId = new StringBuilder();
		
		// Convert base 10 to base 36 from least significant digit to most significant
		do {
			int remainder = (int) (number % base);
			linkId.append(alphabet.charAt(remainder));
			number /= base;
		} while (number > 0);
		
		linkId.reverse();
		return linkId.toString();
	}
	
	public static int decode(String linkId) {
		int number = 0;
		
		for (int i = 0; i < linkId.length(); i++) {
			int position = alphabet.indexOf(linkId.charAt(i));
			number += position * (int) Math.pow(base, linkId.length() - i - 1);
		}
		
		System.out.println("");
		
		return number;
	}

}