Get the offset between GMT and the local timezone - Java java.util

Java examples for java.util:Time

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Description

Get the offset between GMT and the local timezone

Demo Code


//package com.java2s;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

public class Main {
    public static void main(String[] argv) throws Exception {
        System.out.println(getDefaultTimeZoneOffset());
    }//from  w  ww  .  java2 s .  c o m

    public static final long SECOND_FACTOR = 1000;
    public static final long MINUTE_FACTOR = 60 * SECOND_FACTOR;
    public static final long HOUR_FACTOR = 60 * MINUTE_FACTOR;

    /**
     * Get the offset between GMT and the local timezone
     * @return the offset
     */
    public static long getDefaultTimeZoneOffset() {
        long offset = 0;
        TimeZone zn = TimeZone.getDefault();
        Calendar local = Calendar.getInstance();
        local.setTime(new Date(System.currentTimeMillis()));

        // the offset to add to GMT to get local time, modified in case of
        // daylight savings
        int time = (int) (local.get(Calendar.HOUR_OF_DAY) * HOUR_FACTOR
                + local.get(Calendar.MINUTE) * MINUTE_FACTOR + local
                .get(Calendar.SECOND) * SECOND_FACTOR);
        offset = zn.getOffset(
                1, // era AD
                local.get(Calendar.YEAR), local.get(Calendar.MONTH),
                local.get(Calendar.DAY_OF_MONTH),
                local.get(Calendar.DAY_OF_WEEK), time);
        return offset;
    }
}

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