Can we initialize static variables in a default constructor in Java?

QUESTION----       Define data structure ? Explain Needs and   classification of data structures.

Explain MongoDB and it's Features.

Write a program to print Fibonacci series of n terms where n is input by user :

0 1 1 2 3 5 8 13 21 ..... 

In the Fibonacci series, a number is the sum of the previous 2 numbers that came before it.