how to use the ArrayList variable?

package com.codegym.task.task06.task0614;

import java.util.ArrayList;

/*
Static cats

*/

public class Cat {
    public static ArrayList<Integer> cats;

    public Cat() {
    }

    public static void main(String[] args) {
        for(int i=0;i<10;i++){
            Cat cat = new Cat();

        }
        printCats();
    }

    public static void printCats() {
        cats = new ArrayList<Integer>();
            cats.add(cats);
    }
}