I'm getting error in join method...

Question about the task

Animal set

Java Syntax, Level 8, Lesson 11

Resolved

please help to sort it out.🧐

1. Inside the Solution class, create public static classes Cat and Dog.
2. Implement the createCats method, which should return a set with 4 cats.
3. Implement the createDogs method, which should return a set with 3 dogs.
4. Implement the join method, which should return a combined set of all the animals (all the cats and dogs).
5. Implement the removeCats method, which should remove from the set pets all cats in the set cats.
6. Implement the printPets method, which should display all the animals in the set pets.
Each animal should be on a new line.

Requirements:

The program should display text on the screen.
There should be public static classes Cat and Dog inside the Solution class.
The Solution class's createCats() method must return a Set containing 4 cats.
The Solution class's createDogs() method must return a Set containing 3 dogs.
The Solution class's join() method should return a combined set of all the animals (all the cats and dogs).
The removeCats() method should remove from the set pets all cats in the set cats.
The printPets() method should display all the animals in the set pets. Each animal should be on a new line.

package com.codegym.task.task08.task0820; import java.util.HashSet; import java.util.Set; import java.util.Iterator; import java.util.*; /* Animal set */ public class Solution { public static void main(String[] args) { Set<Cat> cats = createCats(); Set<Dog> dogs = createDogs(); Set<Object> pets = join(cats, dogs); printPets(pets); removeCats(pets, cats); printPets(pets); } public static Set<Cat> createCats() { HashSet<Cat> cats = new HashSet<Cat>(); //write your code here cats.add(new Cat()); cats.add(new Cat()); cats.add(new Cat()); cats.add(new Cat()); return cats; } public static Set<Dog> createDogs() { //write your code here HashSet<Dog> dogs = new HashSet<Dog>(); dogs.add(new Dog()); dogs.add(new Dog()); dogs.add(new Dog()); return dogs; } public static Set<Object> join(Set<Cat> cats, Set<Dog> dogs) { //write your code here HashSet<Object> pets = new HashSet<>(); pets.addAll(cats); pets.addAll(dogs); return pets; } public static void removeCats(Set<Object> pets, Set<Cat> cats) { //write your code here for(Cat s : cats){ pets.remove(s); } } public static void printPets(Set<Object> pets) { //write your code here for(Object s: pets){ System.out.println(pets); } } //write your code here public static class Cat{}; public static class Dog{}; public static class Object{}; }

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Tata

Level 16 , Hisar, Haryana, India

22 June 2020, 04:07

could anyone tell me my mistake.

Thomas

Level 41 , Bayreuth, Germany

22 June 2020, 06:50

try to remove line 76. Other than that I have no idea. My guess is, that with overwriting the Object class you have a new type Object that is not the mother of all classes anymore but something of its own. So pet and dog don't inherit from the oroginal Object class anymore. However your set in the join method only accepts objects from type Object (as said, cats and dogs aren't descendants of it). After removing your Object class all should be back to normal and Cats and Dogs descendants of the true Object.

Tata

Level 16 , Hisar, Haryana, India

22 June 2020, 07:04

Thank you.😊