Calculate time ago, for social media, forum applications. Ex: "Just now", "a minute ago", "2 weeks ago", "5 years ago", "Yesterday"

CalculateTimeAgo.java

public static String calculateTimeAgo(long timeStamp) {

        long timeDifference;
        long unixTime = System.currentTimeMillis() / 1000L;  //get current time in seconds.
        int j;
        String[] periods = {"s", "min", "hour", "day", "week", "month", "year", "decade"};
        // full time intervals like seconds, minutes, days and so on
        double[] lengths = {60, 60, 24, 7, 4.35, 12, 10};
        timeDifference = unixTime - timeStamp;
        String tense = "ago";
        String plural = "s";
        for (j = 0; timeDifference >= lengths[j] && j < lengths.length - 1; j++) {
            timeDifference /= lengths[j];
        }
        if (timeDifference > 1 && j> 0){
            return  timeDifference + " " + periods[j] + plural + " " + tense;
        }else if (timeDifference < 2 && j>=3){
            if(j == 3) {
                return "Yesterday";
            }
            return "a" + " " + periods[j] + " " + tense;
        }else {
            if(timeDifference <= 59 &&  periods[j].equals("s")){
                return "just now";
            }
            return timeDifference + " " + periods[j] + " " + tense;
        }
    }