So, it is not supported for below API 26.
You can use the java.time functionality in earlier Android. Use the back-port.
So, I need an alternate solution for this.
No, you don’t.
Keep your code as-is. The back-port carries nearly the same API. So you’ll need do little more than swap your import statements.
ThreeTen-Backport
Most of the java.time functionality is back-ported to Java 6 and Java 7 in the ThreeTen-Backport project.
This project is led by the same man, Stephen Colebourne, who leads the JSR 310 spec, the java.time implementation, and Joda-Time.
ThreeTenABP
The ThreeTen-Backport project is further adapted to Android specifically in the ThreeTenABP project.
Code
ZoneId z = ZoneId.systemDefault() ; // Or ZoneId.of( "Africa/Tunis" )
LocalDate today = LocalDate.now( z ) ;
LocalDate localDate = today.with( org.threeten.bp.temporal.TemporalAdjusters.previousOrSame( DayOfWeek.SUNDAY ) ) ;
List< LocalDate > dates = new ArrayList<>( 7 ) ;
for( int i = 0 ; i < 7 ; i ++ ) {
localDate = localDate.plusDays( i ) ;
dates.add( localDate ) ;
}