Co dokładnie wnoszą te zapisy, o które pytam?

public class Solution {
    public static void main(String[] args) {
        Female female1 = new Female("Alice");
        System.out.println("Created new Female object named " + female1);
        Female female2 = new Female("Jenna");
        System.out.println("Created new Female object named " + female2);
        Male male1 = new Male("Mark");
        System.out.println("Created new Male object named " + male1);
        Male male2 = new Male("Chris");
        System.out.println("Created new Male object named " + male2);
        // at this point all the objects above have their partner set NULL

        System.out.println("All objects created\n\n" +
                "Here are what the partners of each object are set to:");
        printPartners(female1, female2, male1, male2);
        System.out.println();

        System.out.println("Setting " + male1 + "'s partner to " + female1);
        male1.partner = female1;
        System.out.println("Setting " + male2 + "'s partner to " + female2);
        male2.partner = female2;
        // the Male objects now have their partner set, the Female objects still have NULL partners
        System.out.println();

        System.out.println("Here are what the partners are set to:");
        printPartners(female1, female2, male1, male2);
        System.out.println();
    }

private static void printPartners(Female female1, Female female2, Male male1, Male male2) {
        System.out.println("Partner of " + female1 + ": " + female1.partner);
        System.out.println("Partner of " + female2 + ": " + female2.partner);
        System.out.println("Partner of " + male1 + ": " + male1.partner);
        System.out.println("Partner of " + male2 + ": " + male2.partner);
    }

    public static class Male {
        public Female partner;
        String name;

        Male(String n) {
            name = n;
        }

        @Override
        public String toString() {
            return name;
        }
    }

    public static class Female {
        public Male partner;
        String name;

        Female(String n) {
            name = n;
        }

        @Override
        public String toString() {
            return name;
        }
    }
}