What is LocalDate in Java 8 ?

LocalDate class is an immutable & thread safe class. Its based on ISO-8601 calendar system.

It represents a date without any time components. Its date format often viewed in the form year-month-day {2021-11-14}.

Using this class, you can also access other data fields like :

    > day-of-year

    > day-of-week

    > week-of-year

Example:

public class LocalDateEx{
    
    public static void main(String[] args) {
        LocalDate date = LocalDate.of(2021, 4, 14);
        System.out.println("Year of the given date "+ date.getYear());
        System.out.println("Month of the given date "+ date.getMonth());
        System.out.println("day of week of the given date "+ date.getDayOfWeek());
        System.out.println("day of month of the given date "+ date.getDayOfMonth());
        System.out.println("day of year of the given date "+ date.getDayOfYear());
        System.out.println("day of year of the given date "+ date.getDayOfYear());
        System.out.println("month of year(1 to 12) of the given date "+

                                                                                             date.getMonthValue());

        System.out.println("is given date a leap year? "+ date.isLeapYear());
        System.out.println(date);
    }

}

Factorial of any number in Java 8 - using reduction

Reduction - will reduce a stream of values to a result by using an identity (may be an initial value) and a function that will be applied internally on that stream. This processing may not be sequentially, its parallel stream.

import java.util.stream.LongStream;

public class Factorial {
    public static void main(String[] args) {
    System.out.println(facto(5));
}

public static int facto(int n){
    return IntStream.rangeClosed(1, n)
            .reduce(1, (int a, int b) -> a * b);
}
}

we can either use LongStream or IntStream. 

LongStream.rangeClosed(1, n) gives stream of values from 1 to n, 
n is included here.
if you want to exclude nth value, 
you can use
LongStream.range(1, n) gives stream of values from 1 to n-1.
reduce function will apply a function a*b with 1 as initial value
 (also known as identity)
Its the similar operation as the following code.
long result = identity;
*     for (long element : this stream)
*         result = accumulator.applyAsLong(result, element)
*     return result;
But the above code performs the same operation in sequential manner, 
but the reduce will apply the function in parallel form.