Here you can find the source of getDiffTimeZoneRawOffset(String timeZoneId)
public static int getDiffTimeZoneRawOffset(String timeZoneId)
//package com.java2s; //License from project: Apache License import java.util.*; public class Main { public static int getDiffTimeZoneRawOffset(String timeZoneId) { return TimeZone.getDefault().getRawOffset() - TimeZone.getTimeZone(timeZoneId).getRawOffset(); }// w w w . j a v a 2 s. c om }