How to make an Android App expires after a fixed time period

Question

I'd like to program an app that, will be avaliable for only a month. I'd like to check when starting the app whether it's over that that given date( 2020 may. 22, but I don't know how to do that. Could somebody tell me how to compare the current time with a preseted date?

Have look into date comparision https://stackoverflow.com/questions/2592501/how-to-compare-dates-in-java OR https://www.geeksforgeeks.org/compare-dates-in-java/ — ajayg2808, Apr 22 '20 at 17:18
Does this answer your question? [How to compare dates in Java?](https://stackoverflow.com/questions/2592501/how-to-compare-dates-in-java) — Ryan M, Apr 22 '20 at 23:38

score 1 · Accepted Answer · answered Apr 22 '20 at 17:36

put this code in your app's onCreate() method and change the date. The doSomething() method will be called once the date expires.

String expiryDateString = "22-May-2020"; // upcoming date
DateFormat formatter = new SimpleDateFormat("dd-MMM-yyyy");
Date expiryDate = formatter.parse(expiryDateString);

if(System.currentTimeMillis() > expiryDate.getTime()){
    // app is expired
    doSomething();
}

but please note that this is not a secure method as one can change the system time and date and this test fails. So a better method would be to use flags in the server and check it every time the app starts.

Please don’t teach the young ones to use the long outdated and notoriously troublesome `SimpleDateFormat` class. At least not as the first option. And not without any reservation. Today we have so much better in [`java.time`, the modern Java date and time API,](https://docs.oracle.com/javase/tutorial/datetime/) and its `DateTimeFormatter`. Yes, you can use it on Android. For older Android see [How to use ThreeTenABP in Android Project](https://stackoverflow.com/questions/38922754/how-to-use-threetenabp-in-android-project). — Ole V.V., Apr 23 '20 at 04:58

score 0 · Answer 2 · answered Apr 22 '20 at 17:15

Make a static variable that contains the current time and check it when the program starts (or in a loop if that's what you require)

public class Main {
    private static final long DATE_STARTED = 1587575414548;

    if(DATE_STARTED + 2592000000 < System.currentTimeInMillis()) { // 2592000000 is 30 days in milliseconds
        // Handle stuff here
    }
}

score 0 · Answer 3 · answered Apr 22 '20 at 17:31

Going off of @JackChap77's comment, if you want to find the current time, use new Date().getTime() to retrieve the current time in milliseconds and then store that in a final variable. Make sure to only use it once, though, as you don't want to retrieve the current time each time the program is loaded.

How to make an Android App expires after a fixed time period

3 Answers3