Родственные связи

package com.javarush.task.task06.task0621;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
/* 
Родственные связи кошек
*/
 
public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
 
        String grandFather = reader.readLine();
        Cat GrandFather = new Cat(grandFather);
 
        String grandMother = reader.readLine();
        Cat GrandMother = new Cat(grandMother);
 
        String father = reader.readLine();
        Cat Father = new Cat(father,GrandFather);
 
        String mother = reader.readLine();
        Cat Mother = new Cat(mother,GrandFather,GrandMother);
 
        String sun = reader.readLine();
        Cat Sun = new Cat(sun);
 
        String daughter = reader.readLine();
        Cat Daughter = new Cat(daughter);
 
 
        System.out.println(GrandFather);
        System.out.println(GrandMother);
        System.out.println(Father);
        System.out.println(Mother);
        System.out.println(Sun);
        System.out.println(Daughter);
    }
 
    public static class Cat {
        private String name;
        private Cat Mother;
        private Cat Father;
        private Cat GrandMother;
        private Cat GrandFather;
        private Cat Sun;
        private Cat Daughter;
 
        Cat(String name) {
            this.name = name;
        }
 
        Cat(String name, Cat GrandFather) {
            this.name = name;
            this.GrandFather = GrandFather;
        }
        Cat(String name, Cat GrandFather,Cat GrandMother) {
            this.name = name;
            this.GrandFather = GrandFather;
            this.GrandMother=GrandMother;
        }
        Cat(String name, Cat GrandFather, Cat GrandMother, Cat Father, Cat Mother) {
            this.name = name;
            this.GrandFather = GrandFather;
            this.GrandMother=GrandMother;
            this.Father=Father;
            this.Mother=Mother;
        }
 
 
         @Override
        public String toString() {
            if (this.Sun == null && this.Daughter==null && this.Father ==null && this.Mother ==null)
                return "The cat's name is " + name + ", no mother, no father";
            else if (this.GrandFather !=null && this.GrandMother ==null && this.Sun==null && this.Daughter==null)
                return "The cat's name is " + name + " no mother, father is " + GrandFather.name;
            else if (this.GrandFather !=null && this.GrandMother !=null && this.Sun==null && this.Daughter==null)
                return "The cat's name is " + name + ", mother is " + GrandMother.name + ", no father";
            else 
                return "The cat's name is " + name + ", mother is " + Mother.name + ", father is "+Father.name;
        }
    }
}

public static void main(String[] args) throws IOException {
        Cat grandFather = new Cat("grandFather");
        Cat grandMother = new Cat("grandMother");
        Cat father = new Cat("father").setFather(grandFather);
        Cat mother = new Cat("mother").setMother(grandMother);
        Cat daughter = new Cat("daughter").setFather(father).setMother(mother);
        Cat son = new Cat("son").setFather(father).setMother(mother);
 
        System.out.println(son.toString());
 
 
    }
 
    public static class Cat {
        private final String name;
        private Cat mother;
        private Cat father;
 
        public Cat(String name) {
            this.name = name;
        }
 
        public String getName() {
            return name;
        }
 
        public Cat getMother() {
            return mother;
        }
 
        public Cat getFather() {
            return father;
        }
 
        public Cat setMother(Cat mother) {
            this.mother = mother;
            return this;
        }
 
        public Cat setFather(Cat father) {
            this.father = father;
            return this;
        }
 
        @Override
        public String toString() {
            String s = name+" - ";
            if (nonNull(mother)) {
                s += mother.toString();
            }
            if (nonNull(father)) {
                s += father.toString();
            }
            return s;
        }
    }