Connect to objects using one call (Partner in Java)

I’m struggling with Java and need some help with 1-1 associations.
Sorry if I’m wording something wrong, I don’t know how to word it properly in English.

I want to connect both partner1 and partner2 using one call. Before the call, partner1 and partner2 is not connected, but after, they are. I can’t wrap my head around and have been stuck for hours.

Here is what I have so far:

public class Partner {

    private String name;
    private Partner partner;

    public String getName() {
        return this.name;
    }

    public Partner getPartner() {
        return this.partner;
    }

    public Partner(String name) {
        this.name = name;
    }

    public void setPartner(Partner person) {
        if (this == person) {
            throw new IllegalArgumentException("You can not marry yourself!");
        } else {
            this.partner = person;
        }

    }

    @Override
    public String toString() {
        return "Partner [name=" + name + ", partner=" + partner + "]";
    }

    public static void main(String[] args) {
        Partner p1 = new Partner("Mickey");
        Partner p2 = new Partner("Minnie");
        p1.setPartner(p2);
        System.out.println(p1.getPartner());
    }
}

>Solution :

You need to do the other association too, but don’t use person.setPartner(this) because it would call it then the other and you’ll go deep into recursion until a StackOverflowError

public void setPartner(Partner person) {
    if (this == person) {
        throw new IllegalArgumentException("You can not marry yourself!");
    } // else isn't mandatory as code execution whould stop if first branch taken
    this.partner = person;
    person.partner = this;
}

For the same reason, you may use partner.name. If you keep partner, it’ would call it’s toString which would call it’s partner toString , then road to StackOverflowError

@Override
public String toString() {
    return "Partner [name=" + name + ", partner=" + partner.name + "]";
}