Java的一道算法题

public class ValueRefrence {


    public static void main(String[] args) {
        
        test1(); // 结果为 0 3
    }

    public static void test1() {

        Integer i = new Integer(0);
        //Integer@853 -----1
        add(i);
        //Integer@853 -----5
        System.out.println(i);//0
        i +=3;
        //Integer@864 -----6
        System.out.println(i);//3
    }

    static void add(Integer i) {

        //Integer@853 -----2
        i = i + 3;
        //Integer@864 -----3
        i = new Integer(i);//3
        //Integer@865 -----4
    }

}