Counter.java

package Counter;


public class Counter {
    private int num;

    public Counter(int num) {
        this.num = num;
    }

    public int next() {
        this.num += 1;
        return this.num;
    }
}

Main.java

import Counter.Counter;

public class Main {

    public static void main(String[] args) {
        Counter counter = new Counter(0);
        for (int i = 0; i < 10; i++) {
            System.out.println(counter.next());
        }
    }
}