# HexFraction.java :  » Geo » geohashdroid » net » exclaimindustries » tools » Android Open Source

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 geohashdroid » net » exclaimindustries » tools » HexFraction.java ``````/** * HexFraction.java * Copyright (C)2008 Nicholas Killewald * * This file is distributed under the terms of the BSD license. * The source package should have a LICENCE file at the toplevel. */ package net.exclaimindustries.tools; import java.math.BigDecimal; /** * Contains a static method for parsing a hex string as if it were the * fractional part of a number and returning its fractional float value. * * @author Nicholas Killewald */ public class HexFraction { /** * Converts a string, presumably the fractional part of a hex number, into * its fractional decimal counterpart. Don't feed it a negative. * * @param s * the hex string to convert * @return a float value of the hex string * @throws NumberFormatException * parsing error with the string */ public static double calculate(String s) throws NumberFormatException { // We're dealing with values to the precision of 1/(16^16). I think // BigDecimal is quite called for in this case. BigDecimal curvalue = new BigDecimal(0); // We need to parse the string one character at a time and continuously // calculate each digit's fractional hex value. Note, this WILL hurt. for (int i = 0; i < s.length(); i++) { // Get the hexit. String hexit = s.substring(i, i + 1); // Make it into an integer. int part = Integer.parseInt(hexit, 16); // Now divide it out. BigDecimal d1 = new BigDecimal(part); BigDecimal d2 = new BigDecimal(16); d2 = d2.pow(i + 1); curvalue = curvalue.add(d1.divide(d2)); // Then repeat for the entire string. } // Finally, return at will! return curvalue.doubleValue(); } } ``````