Java tutorial
//package com.java2s; //License from project: Open Source License import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class Main { public static String formatExpirationDate(String text) { try { switch (text.length()) { case 1: int digit = Integer.parseInt(text); if (digit < 2) { return text; } else { return "0" + text + "/"; } case 2: int month = Integer.parseInt(text); if (month > 12 || month < 1) { // Invalid digit return text.substring(0, 1); } else { return text + "/"; } case 3: if (text.substring(2, 3).equalsIgnoreCase("/")) { return text; } else { text = text.substring(0, 2) + "/" + text.substring(2, 3); } case 4: int yearDigit = Integer.parseInt(text.substring(3, 4)); String year = String.valueOf(Calendar.getInstance().get(Calendar.YEAR)); int currentYearDigit = Integer.parseInt(year.substring(2, 3)); if (yearDigit < currentYearDigit) { // Less than current year invalid return text.substring(0, 3); } else { return text; } case 5: SimpleDateFormat simpleDateFormat = new SimpleDateFormat("MM/yy"); simpleDateFormat.setLenient(false); Date expiry = simpleDateFormat.parse(text); if (expiry.before(new Date())) { // Invalid exp date return text.substring(0, 4); } else { return text; } default: if (text.length() > 5) { return text.substring(0, 5); } else { return text; } } } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } // If an exception is thrown we clear out the text return ""; } }