Question

This is a question from a past exam paper. The question asks to declare a variable c of type Counter in a new class. I should then intialise it to a new instance of Counter with n taking a value of 100. I must then increment its n field twice. Then print the value of the n field to System.out.

I have done both classes, but i am not sure about the Counter2 class. I think i may be declaring the Counter variable wrong.

public class Counter {
    private int n;
    public int x;

    public Counter(int theN){
        this.n=theN;
    }

    public int getN(){
        return n;
    }

    public void inc(){
        x = 1+ getN();
    }
}

public class Counter2{
    Counter c;

    public int incrementTwice(){
        int i = 0;

        while(i<2){
            c.inc();
            i++;
        }
        return c.x;
    }

    public static void main (String[] args){
        c = new Counter(100);
        int finalResult = c.getN();
        System.out.println(finalResult);
    }
}

Answer 1

In inc() you are not actually incrementing n. You are setting x to n+1.

So, it does not matter how many times you run inc, before the first run you will have n = initial Value and x=0, after the first run and following you have n = initialValue and x = n + 1