Determinating if a given string time is in the past, using Java Calendar (Android)

Question

I'm trying to write 'isPast(String dateStr)' function, which receives date string and returns true if it's in the past and false otherwise.

private static boolean isPast(String dateStr) {
    Calendar c = GregorianCalendar.getInstance();

    int currentYear = c.get(Calendar.YEAR);
    int currentMonth = c.get(Calendar.MONTH);
    int currentDay = c.get(Calendar.DAY_OF_MONTH);
    int currentHour = c.get(Calendar.HOUR_OF_DAY);
    int currentMinute = c.get(Calendar.MINUTE);
    c.set(currentYear, currentMonth, currentDay, currentHour, currentMinute);
    Date now = c.getTime();

    SimpleDateFormat sdfDates = new SimpleDateFormat("dd/m/yyyy");

    Date date = null;
    try {
        date = sdfDates.parse(dateStr);

    } catch (ParseException e) {
        e.printStackTrace();
    }

    if (now.compareTo(date) == 1){
        System.out.println(dateStr + " date given is past");
        return true;
    }
    System.out.println(dateStr + " date given is future");
    return false;
}

And i'm calling it with:

 String str1 = "22/04/2018";
 String str2 = "22/01/2018";
 System.out.println(isPast(str1));
 System.out.println(isPast(str2));

And the output is:

22/04/2018 date given is past
22/01/2018 date given is past

What is going on here? It's not true. I'm on this for too long - it should be simple, obviously i'm missing something with that Calendar object...

`SimpleDateFormat sdfDates = new SimpleDateFormat("dd/M/yyyy");` lower case `m` is minutes. — Elliott Frisch, Feb 22 '18 at 22:27
"`if (now.compareTo(date) == 1){`" the contract on `compareTo` is that it returns `<0`, `==0` or `>0`. You shouldn't look for *exactly* 1. — Andy Turner, Feb 22 '18 at 22:28
Convert the String to `Date` (preferably `LocalDate`) and use api functionality to test it (ie `before`/`after`) — MadProgrammer, Feb 22 '18 at 22:28
I was going to recommend before/after methods of Date class after converting String to Date but @MadProgrammer beat me to it :-) — Balwinder Singh, Feb 22 '18 at 22:30
I’m also not sure what you hope to accomplish with `c.set` and simply passing the values you already extracted back in? — MadProgrammer, Feb 22 '18 at 22:32
I'm trying to get the current time (Now). If you can suggest me for another way - I'd be glad. Thanks everyone else for the helpfull comments — jonb, Feb 22 '18 at 22:38
@JohnSnowTheDeveloper To get current time: `Date now = new Date();` — Andreas, Feb 22 '18 at 22:48
I'm working with android, the Date constructor is depreached — jonb, Feb 22 '18 at 22:49
@JohnSnowTheDeveloper I don't see `android` tagged in your question. — Andreas, Feb 22 '18 at 22:51
My bad, I didn't know the constructor exists in Java, adding tag now — jonb, Feb 22 '18 at 22:52
@JohnSnowTheDeveloper The `Date()` constructor is not listed as deprecated: https://developer.android.com/reference/java/util/Date.html#Date() — Andreas, Feb 22 '18 at 22:53
The `Date`, `Calendar` and `SimpleDateFormat` classes are long outdated anyway, and `SimpleDateFormat` in particular notoriously troublesome. Consider adding [ThreeTenABP](https://github.com/JakeWharton/ThreeTenABP) to your Android project and then use [java.time, the modern Java date and time API,](https://docs.oracle.com/javase/tutorial/datetime/) instead of the old classes. — Ole V.V., Feb 23 '18 at 06:02
This question has been asked and answered many times already alright; but the linked question misses the problem in this question. Instead this is a duplicate of [Why SimpleDateFormat is giving Month as January instead of October in this case?](https://stackoverflow.com/questions/33454024/why-simpledateformat-is-giving-month-as-january-instead-of-october-in-this-case). — Ole V.V., Feb 23 '18 at 06:18
Other times the same question has been asked: (1) [Month in simple date formatter always return JANUARY](https://stackoverflow.com/questions/48184541/month-in-simple-date-formatter-always-return-january). (2) [Month issue in SimpleDateFormat class](https://stackoverflow.com/questions/35645551/month-issue-in-simpledateformat-class). (3) [How can I add one month to change into the milliseconds?](https://stackoverflow.com/questions/48768874/how-can-i-add-one-month-to-change-into-the-milliseconds). — Ole V.V., Feb 23 '18 at 06:22

score 4 · Accepted Answer · answered Feb 22 '18 at 22:42

4

Use LocalDate that is available in Java 8

  public static void main(String[] args) {

    String str1 = "22/04/2018";
    String str2 = "22/01/2018";
    System.out.println(isPast(str1));
    System.out.println(isPast(str2));
  }


  private static boolean isPast(String dateStr) {

    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy");
    LocalDate dates = LocalDate.parse(dateStr, formatter);

    return dates.isBefore(LocalDate.now());
  }

answered Feb 22 '18 at 22:42

Evilguy

306
2
14

It's good, but what if I want to consider the hh:mm as well ? DateTimeParse can't parse 23:40 as format hh:mm, do you know how can I overcome it ? – jonb Feb 22 '18 at 22:48
2

@JohnSnowTheDeveloper Use `LocalDateTime` instead of `LocalDate` and use format string `"dd/MM/yyyy HH:mm"`. – Andreas Feb 22 '18 at 22:49
FYI… Much of the java.time functionality is back-ported to Java 6 & 7 in [***ThreeTen-Backport***](http://www.threeten.org/threetenbp/). For earlier Android, the [***ThreeTenABP***](https://github.com/JakeWharton/ThreeTenABP) project adapts *ThreeTen-Backport*. See [*How to use ThreeTenABP…*](http://stackoverflow.com/q/38922754/642706). – Basil Bourque Feb 22 '18 at 23:44

Ari Singh · Answer 2 · 2018-02-22T22:49:52.463

Try this:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Test {
    private static final SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
    public static void main(String[] args) {

         String str1 = "22/04/2018";
         String str2 = "22/01/2018";
         String str3 = "xx/01/2018";

         Date now = new Date();

         testDate (str1, now);
         testDate (str2, now);
         testDate (str3, now);
    }

    private static void testDate(String str, Date now) {
         try {
            if (sdf.parse(str).before(now)) {
                 System.out.println(str + " is in the past.");
             } else {
                 System.out.println(str + " is in the future.");
             }
        } catch (ParseException e) {
             System.out.println("Date not in format dd/MM/yyyy : " + str);
        } 
    }
}

Output:

22/04/2018 is in the future.
22/01/2018 is in the past.
Date not in format dd/MM/yyyy : xx/01/2018

If you have to use Calendar, try this:

    private static void testDateUsingCalendar (String str, Date now) {
         try {
            String[] split = str.split("/");
            Calendar c = GregorianCalendar.getInstance();

            c.set(Integer.valueOf(split[2]), Integer.valueOf(split[1]), Integer.valueOf(split[0]));
            if (c.getTime().before(now)) {
                 System.out.println(str + " is in the past.");
             } else {
                 System.out.println(str + " is in the future.");
             }
        } catch (Exception e) {
             System.out.println("Date not in format dd/MM/yyyy : " + str);
        } 
    }

Determinating if a given string time is in the past, using Java Calendar (Android)

2 Answers2