How to know how many times a method has been called from main class?

Question

My problem is to find out how many times the weight() method is being called from the main class. I should calculate it in the totalWeightsMeasured() method.

The output of the code should be 0,2,6. (EDIT// I had earlier here 0,2,4 but the output should really be 0,2,6)

But I just don't have any idea how can you calculate it and I have tried to google and everything but I just don't know how to do it. (and you are not supposed to add any more instance variables)

CLASS:

public class Reformatory
{
    private int weight;



    public int weight(Person person)
    {
        int weight = person.getWeight();

        // return the weight of the person
        return weight;
    }
    public void feed(Person person)
    {
        //that increases the weight of its parameter by one.
        person.setWeight(person.getWeight() + 1);

    }
    public int totalWeightsMeasured()
    {


        return 0;
    }

}

MAIN:

public class Main
{

    public static void main(String[] args)
    {
        Reformatory eastHelsinkiReformatory = new Reformatory();

        Person brian = new Person("Brian", 1, 110, 7);
        Person pekka = new Person("Pekka", 33, 176, 85);

        System.out.println("total weights measured "+eastHelsinkiReformatory.totalWeightsMeasured());

        eastHelsinkiReformatory.weight(brian);
        eastHelsinkiReformatory.weight(pekka);

        System.out.println("total weights measured "+eastHelsinkiReformatory.totalWeightsMeasured());

        eastHelsinkiReformatory.weight(brian);
        eastHelsinkiReformatory.weight(brian);
        eastHelsinkiReformatory.weight(brian);
        eastHelsinkiReformatory.weight(brian);

        System.out.println("total weights measured "+eastHelsinkiReformatory.totalWeightsMeasured());
    }
}

Answer 1

The trick is to use the existing instance variable weight, which is not used yet, as the counter.

public class Reformatory
{
    private int weight;

    public int weight(Person person)
    {
        int weight = person.getWeight();

        this.weight++;

        // return the weight of the person
        return weight;
    }
    public void feed(Person person)
    {
        //that increases the weight of its parameter by one.
        person.setWeight(person.getWeight() + 1);

    }
    public int totalWeightsMeasured()
    {
        return weight;
    }

}

Answer 2

As pointed out by Satya, introduce a static counter variable as follows:

public class Reformatory {
    private static int weightMessurements = 0;

    public int weight(Person person) {
        // increment counter
        weightMessurements++;
        // messure weight
        return person.getWeight();
    }

    public void feed(Person person) {
        // increase weight
        person.setWeight(person.getWeight() + 1);
    }

    public int totalWeightsMeasured() {
        int result = weightMessurements;
        // reset counter so that the output matches 0,2,4 instead of 0,2,6
        weightMessurements = 0;
        return result;
    }
}