TimeUtils.java

package com.samknows.measurement.util;

import java.sql.Date;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.GregorianCalendar;

/**
 * It is not thread safe!
 * @author ymyronovych
 *
 */
public class TimeUtils {
	public static final String dateLogFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ";
	public static String logString(long time){
		SimpleDateFormat sdf = new SimpleDateFormat(dateLogFormat);
		return sdf.format(new Date(time));
	}
	
	private static Calendar cleanToDay(Calendar c) {
		c.set(GregorianCalendar.HOUR_OF_DAY, 0);
		c.set(GregorianCalendar.MINUTE, 0);
		c.set(GregorianCalendar.SECOND, 0);
		c.set(GregorianCalendar.MILLISECOND, 0);
		return c;
	}
	
	private static Calendar cleanToMonth(Calendar c) {
		c = cleanToDay(c);
		c.set(GregorianCalendar.DAY_OF_MONTH, 0);
		return c;
	}
	
	public static long getStartDayTime() {
		return cleanToDay(GregorianCalendar.getInstance()).getTimeInMillis();
	}
	
	public static long getStartMonthTime() {
		return cleanToMonth(GregorianCalendar.getInstance()).getTimeInMillis();
	}
	
	public static long getStartDayTime(long millis) {
		Calendar calendar = GregorianCalendar.getInstance();
		calendar.setTimeInMillis(millis);
		return cleanToDay(calendar).getTimeInMillis();
	}
	
	public static long getStartNextDayTime() {
		Calendar c = cleanToDay(GregorianCalendar.getInstance());
		c.add(GregorianCalendar.DAY_OF_YEAR, 1);
		return c.getTimeInMillis();
	}

	public static long getStartNextDayTime(long millis) {
		Calendar calendar = GregorianCalendar.getInstance();
		calendar.setTimeInMillis(millis);
		calendar.add(GregorianCalendar.DAY_OF_YEAR, 1);
		cleanToDay(calendar);
		return calendar.getTimeInMillis();
	}
	
	public static long daysToMillis(long days) {
		return days * 24 * 60 * 60 * 1000;
	}
	
	public static long hoursToMillis(long hours) {
		return hours * 60 * 60 * 1000;
	}
	
	public static long minutesToMillis(long minutes) {
		return minutes * 60 * 1000;
	}
	
	public static int millisToHours(long millis){
		return (int) millis/(1000*3600);
	}
	
	public static long getPreviousDayInMonth(int i){
		Calendar c = GregorianCalendar.getInstance();
		long now = c.getTimeInMillis();
		c = cleanToDay(c);
		c = setDay(c,i);
		//use the previous month
		if(now <= c.getTimeInMillis()){
			c.add(GregorianCalendar.MONTH, -1);
			c = setDay(c,i);
		}
		return c.getTimeInMillis();
	}
	
	public static Calendar setDay(Calendar c, int day){
		int actualDay = Math.min(day, c.getActualMaximum(GregorianCalendar.DAY_OF_MONTH));
		c.set(GregorianCalendar.DAY_OF_MONTH, actualDay);
		return c;
	}
	
	public static String getDayOfMonthFrom1AsStringWithNoSuffix(int n){
		return Integer.toString(n);
		/*
		String ret = n+"";
		// If you want to use a suffix, the following doesn't work properly in non-English locales.
		if(n>=11 && n <=13){
			ret += "th";
		}else{
			switch(n % 10){
				case 1: ret += "st"; break;
				case 2: ret += "nd"; break;
				case 3: ret += "rd"; break;
				default: ret += "th";
			}
		}
		return ret;
		*/
	}
}