Android get Date difference

Question

I want to implement Question of the day feature in my application. If user use that feature once in a day he can not be able to access that till the day change. I am able to fetch when the feature access first but how can i check this date time for next time.

How can i get the date is changed or not.

Thanks in advance.

Answer 1

You can use a combination of timestamp, shared preferences and the use of method isToday(long when) located at android.text.format.DateUtils

code example:

SharedPreferences userDetails = context.getSharedPreferences("userdetails", MODE_PRIVATE);
long sharedPreferenceTimestamp= userDetails.getLong("lastquestiontime", 0); // 0: 1/1/1970
if(!DateUtils.isToday(sharedPreferenceTimestamp)) {
   // --> show the Question HERE! <--

   // update the value of last question show!
   SharedPreferences.Editor editor = userDetails.edit();
   editor.putLong("lastquestiontime", System.currentTimeMillis()); // value to store
   editor.commit();
}

Answer 2

I prefer using unix time to calculate date. The unix time is the number of milliseconds since Jan. 1, 1970, midnight GMT. You can get this number by calling Date.getTime() method.

Because you need the number of the elapsed days so you should divide this number by 24*60*60*1000. After that you don’t have to do anything else just compare the two numbers. If the numbers are the same, day does not changed.

Answer 3

Cant you use a shared preference and add the username and the date as the key. Then when you retrieve the username the next time, you can retrieve the date for that user and compare.

Answer 4

tl;dr

LocalDate.now( ZoneId.systemDefault() )
         .isEqual( LocalDate.parse( "2018-01-23" ) ) 

java.time

The modern approach uses the java.time classes built into Java 8 and later, and recent versions of Android. For earlier Android, see last bullets below.

You do not define what "once a day means". I'll assume you mean the date for the user’s particular time zone.

LocalDate

The LocalDate class represents a date-only value without time-of-day and without time zone.

A time zone is crucial in determining a date. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.

If no time zone is specified, the JVM implicitly applies its current default time zone. That default may change at any moment, so your results may vary. Better to specify your desired/expected time zone explicitly as an argument.

Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).

ZoneId z = ZoneId.of( "America/Montreal" ) ;  
LocalDate today = LocalDate.now( z ) ;

If you want to use the JVM’s current default time zone, ask for it and pass as an argument. If omitted, the JVM’s current default is applied implicitly. Better to be explicit.

ZoneId z = ZoneId.systemDefault() ;  // Get JVM’s current default time zone.

Record that date as text, if you need to track it after the app restarts. Use standard ISO 8601 format, YYYY-MM-DD. The java.time classes use the standard formats by default when parsing/generating strings.

String output = today.toString() ;  // Generate string in standard ISO 8601 format.

Parse that string back to a LocalDate object.

LocalDate localDate = LocalDate.parse( "2018-01-23" ) ;

Compare to today’s date.

Boolean isSameDate = LocalDate.now( z ).isEqual( localDate ) ;

If it is a new date, run your code.

if( ! isSameDate ) { … }  // If not same date…

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About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • Later versions of Android bundle implementations of the java.time classes.
  • For earlier Android, the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….