Java tutorial
//package com.java2s; import java.text.ParseException; public class Main { public static Double diff(Double d1, Double d2) { if (d1 == null) d1 = Double.valueOf(0); if (d2 == null) d2 = Double.valueOf(0); return d1 - d2; } public static Double diff(Object o1, Object o2) { Double returnVal = Double.valueOf(0); if (o1 == null || o2 == null) return returnVal; Double val1 = Double.valueOf(0); Double val2 = Double.valueOf(0); if (o1 instanceof Double) { val1 = (Double) o1; } else { val1 = string2double(o1.toString()); } if (o2 instanceof Double) { val2 = (Double) o2; } else { val2 = string2double(o2.toString()); } returnVal = val1 - val2; return returnVal; } public static Double string2double(String str) { Double returnVal = Double.valueOf(0); try { returnVal = Double.valueOf(str); java.text.NumberFormat nf = java.text.NumberFormat.getInstance(java.util.Locale.ENGLISH); returnVal = Double.valueOf(nf.parse(str).doubleValue()); } catch (ParseException e) { } catch (Exception e) { } return returnVal; } }