Here you can find the source of getHourBeforeTime(int hour)
public static Date getHourBeforeTime(int hour)
//package com.java2s; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; public class Main { public static Date getHourBeforeTime(int hour) { Calendar now = Calendar.getInstance(); now.set(Calendar.HOUR_OF_DAY, now.get(Calendar.HOUR_OF_DAY) - hour); return now.getTime(); }/*from ww w .j av a 2s . c o m*/ public static String getTime(Calendar c) { return getDate(c.getTime(), "HH:mm:ss"); } public static String getDate() { return getDate(getCurDate(), "yyyy-MM-dd"); } public static String getDate(Date date, String format) { String dtstr = ""; if (date == null) { return dtstr; } if (format == null || "".equals(format.trim())) { format = "yyyy-MM-dd"; } SimpleDateFormat sdf = new SimpleDateFormat(format); dtstr = sdf.format(date); return (dtstr == null ? "" : dtstr); } public static String getDate(Date date) { return getDate(date, "yyyy-MM-dd"); } public static Date getDate(long time) { Calendar c = getCurCalendar(); c.setTimeInMillis(time); return c.getTime(); } public static Date getCurDate() { return getCurCalendar().getTime(); } public static Calendar getCurCalendar() { return Calendar.getInstance(); } }