private long next(){
        long val = pos.incrementAndGet();
        return val;
    }
Date 03/05/2015
@author tusroy

Write a program which fills up boolean matrix from top left to bottom right with true. 
This program should support two apis
1) void updateMatrix() which updates last position of matrix with true
2) boolean getVal(int x,int y) return boolean val at matrix[x][y]

This program should be threadsafe.

Solution
Use AtomicLong to increment the value and return old value.

Test cases
1) Try with single thread
2) Try with multiple threads and big matrix size.
src/com/interview/multithreaded/FillupMatrix.java