Here you can find the source of addHours(Date date, int amount)
public static Timestamp addHours(Date date, int amount)
//package com.java2s; import java.sql.Timestamp; import java.util.Calendar; import java.util.Date; public class Main { public static Timestamp addHours(Date date, int amount) { return add(date, Calendar.HOUR_OF_DAY, amount); }/*from w w w . ja v a2s. c o m*/ public static Timestamp add(Date date, int calendarField, int amount) { if (date == null) { throw new IllegalArgumentException("The date must not be null"); } Calendar c = Calendar.getInstance(); c.setTime(date); c.add(calendarField, amount); return new Timestamp(c.getTimeInMillis()); } }