Java Vectors

import java.util.ArrayList;
public class Vectors {
    public Vectors() {
    }

    ArrayList<Integer> vector1 = new ArrayList<Integer>();
    ArrayList<Integer> vector2 = new ArrayList<Integer>();

    public ArrayList default1() {
        vector1.add(1);
        vector1.add(2);
        vector1.add(3);
        return vector1;
    }

    public ArrayList default2() {
        vector2.add(4);
        vector2.add(5);
        vector2.add(6);
        return vector2;
    }

    public void printVectorContent(ArrayList<Integer> v1) {
        for (int i : v1) {
            System.out.println(i);
        }
    }

    public int dot(ArrayList<Integer> v1, ArrayList<Integer> v2) {
        int product = 0;
        for (int i = 0; i < v1.size(); i++) {
            product += v1.get(i) * v2.get(i);
        }
        return product;
    }

    public static void main(String[] args) {
        Vectors test = new Vectors();
        System.out.println("Vector 1: ");
        test.printVectorContent(test.default1());
        System.out.println("Vector 2: ");
        test.printVectorContent(test.default2());
        System.out.println("Dot Product: ");
        System.out.println(test.dot(test.vector1, test.vector2));

    }
    
}
Vectors.main(null);

Vector 1: 
1
2
3
Vector 2: 
4
5
6
Dot Product: 
32