package Data_Structures.Chapter2;

public class Progression {

// instance variable
	protected long current;

	/** Constructs a progression starting at zero. */
	public Progression() {
		this(0);
	}

	/** Constructs a progression with given start value. */
	public Progression(long start) {
		current = start;
	}

	/* Returns the next value of the progression. */
	public long nextValue() {
		long answer = current;
		advance(); // this protected call is responsible for advancing the current value
		return answer;
	}

	/* Advances the current value to the next value of the progression. */
	protected void advance() {
		current++;
	}

	/** Prints the next n values of the progression, separated by spaces. */
	public void printProgression(int n) {
		System.out.print(nextValue()); // print first value without leading space
		for (int j = 1; j < n; j++)
			System.out.print(" " + nextValue()); // print leading space before others
		System.out.println(); // end the line
	}

// Here the problem is to find the nth fibonacci value

// we created new method to store the fibonacci values in an array.
	// this program returns final value in the given n series.
	public long printFinalValueInSeries(int n) {
		long[] nthValue = new long[n];
		for (int i = 0; i < n; i++) {
			nthValue[i] = nextValue();

		}
		return nthValue[n - 1];

	}
}





package Data_Structures.Chapter2;

public class FibonacciProgression extends Progression {

	protected long prev;

	public FibonacciProgression() {
		this(0, 1);
	}

	/** Constructs generalized Fibonacci, with give first and second values. */
	public FibonacciProgression(long first, long second) {
		super(first);
		prev = second - first; // fictitious value preceding the first
	}

	/* Replaces (prev,current) with (current, current+prev). */
	protected void advance() {
		long temp = prev;
		prev = current;
		current += temp;
	}

	
	// We slightly change the driver method to print last value in the progression
	public static void main(String args[]) {

		Progression prog;
		int fibValue = 8;
		prog = new FibonacciProgression(2, 2);
		System.out.print(fibValue + "th value in the Fibonacci progression with 2, 2 as start values is: ");
		System.out.println(prog.printFinalValueInSeries(fibValue));

	}

}


Output:

8th value in the Fibonacci progression with 2, 2 as start values: 42