Here you can find the source of addDayToString(String strDate, int days)
public static final String addDayToString(String strDate, int days)
//package com.java2s; //License from project: Open Source License import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.*; public class Main { private static String defaultDatePattern = "yyyy-MM-dd"; public static SimpleDateFormat dateTimeFormatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); public static final String addDayToString(String strDate, int days) { Calendar cale = toCalendar(strDate); cale.add(Calendar.DAY_OF_YEAR, days); return dateFormatterByPattern(cale.getTime(), "yyyy-MM-dd"); }/*from w w w .j a va2 s . c om*/ private static final Calendar toCalendar(String strDate) { Calendar cale = null; try { Date thisDate = dateTimeFormatter.parse(strDate); cale = Calendar.getInstance(); cale.setTime(thisDate); } catch (Exception e) { return null; } return cale; } public static String dateFormatterByPattern(Date date, String pattern) { SimpleDateFormat sdf = new SimpleDateFormat(pattern); if (date != null) { return sdf.format(date); } else { return sdf.format(new Date()); } } public static Date parse(String strDate) throws ParseException { return parse(strDate, getDatePattern()); } public static Date parse(String strDate, String pattern) { SimpleDateFormat df = new SimpleDateFormat(pattern); try { return df.parse(strDate); } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } return null; } public static Date parse(Date strDate, String pattern) { SimpleDateFormat df = new SimpleDateFormat(pattern); try { return df.parse(df.format(strDate)); } catch (ParseException e) { e.printStackTrace(); } return null; } public static String format(Date date) { return format(date, getDatePattern()); } public static String format(Date date, String pattern) { String returnValue = ""; if (date != null) { SimpleDateFormat df = new SimpleDateFormat(pattern); returnValue = df.format(date); } return (returnValue); } public static String getDatePattern() { return defaultDatePattern; } }