fibo.java

import java.util.NavigableMap;
import java.util.TreeMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.stream.Stream;

public class Fibonacci {

    public static final Fibonacci BASE = new Fibonacci(0, 1);

    public final int previous;
    public final int current;

    public Fibonacci(int previous, int current) {
        this.previous = previous;
        this.current = current;
    }

    public Fibonacci next() {
        return new Fibonacci(current, current + previous);
    }

    public static int of(int number) {
        AtomicInteger i = new AtomicInteger(0);
        NavigableMap<Integer, Integer> map = new TreeMap<>();
        Stream.iterate(Fibonacci.BASE, Fibonacci::next).limit(number + 1).forEach(fibonacci -> {
            map.put(i.getAndIncrement(), fibonacci.previous);
        });
        //System.out.println(map);
        return map.lastEntry().getValue();
    }

    public static void main(String[] args) {
        System.out.println(Fibonacci.of(10));
    }

}