java.sql.Timestamp subclass with ability to parse and hold the raw server string with microseconds and optional format parts. Has usefull method daysFromToday()

Timestamp.java

package com.example;

import android.support.annotation.NonNull;
import android.text.TextUtils;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
import java.util.concurrent.TimeUnit;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Extends the {@link java.sql.Timestamp} to parse server datetime.
 * Additionally stores the raw datetime input.
 * @author Vasili Chyrvon ([email protected])
 */
public class Timestamp extends java.sql.Timestamp {

    // The regex pattern of 2016-03-11T05:10:12.000001-03:50 with groups. Microseconds and timezone is optional.
    private static final Pattern SERVER_DATE_PATTERN = Pattern.compile("([0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2})\\.?([0-9]{6})?([+|-][0-9|\\:]{5})?");
    private static final String DATETIME_FORMAT = "yyyy-MM-dd'T'HH:mm:ssZZZZZ";
    private static final String DEFAULT_TIMEZONE = "+00:00";
    public static final String NANO_NULLS_SUFFIX = "000";

    private String mRaw; // Server date

    public String getRaw() {
        return mRaw;
    }

    void setRaw(String raw) {
        mRaw = raw;
    }

    @SuppressWarnings("deprecation")
    public static Timestamp create(@NonNull String raw) {
        String dateTime;
        String microseconds;
        String timeZone;

        // Parse
        Matcher matcher = SERVER_DATE_PATTERN.matcher(raw.trim());
        if (matcher.find()) {
            dateTime = matcher.group(1);
            microseconds = matcher.group(2);
            timeZone = matcher.group(3);
        } else {
            throw new IllegalArgumentException("Server datetime (" + raw + ") not in the correct format!");
        }

        timeZone = (!TextUtils.isEmpty(timeZone)) ? timeZone : DEFAULT_TIMEZONE;

        // Get date
        String dateTimeAndTimeZone = dateTime + timeZone;
        DateFormat dateFormat = new SimpleDateFormat(DATETIME_FORMAT, Locale.US);

        Date date;
        try {
            date = dateFormat.parse(dateTimeAndTimeZone);
        } catch (ParseException e) {
            throw new RuntimeException("Can't parse '" + dateTimeAndTimeZone + "'!");
        }

        // Create and return timestamp
        Timestamp timestamp = new Timestamp(date.getTime());
        if (!TextUtils.isEmpty(microseconds)) {
            timestamp.setNanos(Integer.parseInt(microseconds + NANO_NULLS_SUFFIX));
        }
        timestamp.setRaw(raw); // Save raw

        return timestamp;
    }

    /**
     * @deprecated Use {@link #create(String)} method instead
     */
    @Deprecated
    public Timestamp(long theTime) {
        super(theTime);
    }

    public int daysFromToday() {
        long theDayMillis = getTime();
        theDayMillis = theDayMillis + TimeZone.getDefault().getOffset(theDayMillis);

        long todayMillis = System.currentTimeMillis();
        todayMillis = todayMillis + TimeZone.getDefault().getOffset(todayMillis);

        long theDay = TimeUnit.MILLISECONDS.toDays(theDayMillis);
        long today = TimeUnit.MILLISECONDS.toDays(todayMillis);
        int difference = (int) (theDay - today);
//        Timber.d("daysFromToday(): theDay = %s,today = %s, difference => %s", theDay, today, difference);
        return difference;
    }
}