Fibonacci with 3 different recursion methods

I’m trying to understand recursion with Java better and I’m doing a program which ist using iteration, head and tail recursion.It should count how many times does the different methods called. What should I add to the head and to the tail part to complete the program? Thank you in advance

public static void main(String[] args) {
}

private static int fibIt(int n) {

    switch (n) {
        case 0:
            return 0;
        case 1:
            return 1;
    }

    int a = 0;
    int b = 1;

    for (int i = 2; i <= n; i++) {
        b = a + b;
        a = b - a;
    }

    return b;
}

private static int fibHr(int n) {

    switch (n) {
        case 0:
            return 0;
        case 1:
            return 1;
        default:
            return fibHr(n - 1) + fibHr(n - 2);
    }
}

private static int fibTr(int n) {

    return fibTr(0, 1, n);

}

private static int fibTr(int a, int b, int n) {
    switch (n) {
        case 0:
            return a;
        case 1:
            return b;
        default:
            return fibTr(b, a + b, n - 1);
    }
}

>Solution :

You can convert each method to an instance method of a class which then holds the counter in a private field, with a getter to expose the value.

public class HeadRecursion {
  private long counter = 0;
  public int fib(int n) {
    ++counter;
    switch (n) {
        case 0:
            return 0;
        case 1:
            return 1;
        default:
            return fibHr(n - 1) + fibHr(n - 2);
    }
  }
  public long getCounter() { return count; }
}

Then you can instantiate your class, run your function and then get and output the counter:

public static void main() {
  final var obj = new HeadRecursion();
  obj.fib(10);
  System.out.println(obj.getCounter());
}