Answer 1

You can sort dates expressed in java.time.LocalDate because it implements the compareTo method.
var d1 = LocalDate.of(2010,11,30);
var d2 = LocalDate.of(1980,3,1);
System.out.println(d1);
System.out.println(d2);
System.out.print(d2.compareTo(d1));
https://docs.oracle.com/javase/8/docs/api/java/time/LocalDate.html

If this is homework, then at least give it a try before asking for help, and post your code attempt when you are stuck. Don't expect others to do your homework.