remove 1 one cat

This worked, but I want to try something else. I want to know which one I am removing, not just the first random one.....

This looks like it works by using Syso to show that Angie was removed (and yes, I print just the object at validation), but the validator says I have not removed a cat: for (Cat cat: cats) { if(cat.name.equals("Angie")){ cats.remove( cat ); } //break; }

As I´ve created only new Object without any name, the only option how to remove some specific cat was with its default "toString" record. But please note that this one also fails - same story as Kent described above:

cats.removeIf(text -> text.toString().contains("com.codegym.test.Solution$Cat@74a14482"));

He is storing the value in HashSet data structure which is defined in line 28 by name set. So, set.add adds the new Cat objectt to set. Since set does not guarantee order, you cannot access its elements like an array or arraylist. You'll have to use iterator to access elements of set and remove them. A simple google search will lead you to this - https://stackoverflow.com/questions/28178554/remove-element-from-set

okey that makes sense... so every time when we want to search for an object we need to know before , what kind of object that we wanted to remove . and we can remove according to that . right ?

A set (or any other collection) will contain same type of objects. For example - a set defined as HashSet<Integer> will only contain Integer values. So, we already know what kind of objects will be present in set. Even if you don't know what kind of objects are there in set, it not a problem. iterator method of set (or any other collection) will return an iterator pointing to first element of set. Now you can traverse through set using iterator with help of a for loop(or any other loop) and remove whatever element you want. You don't need to know the type or index of the element. for example - consider a set {1,2,3,4}. To remove any of the elements, you don't need to know what are the indexes of elements or whether they are float or double or short or int or string or characters. Follow the link to know how to remove element from set using iterator - https://stackoverflow.com/questions/28178554/remove-element-from-set

Okay, but I have no way of specifying which cat to remove. I tried the below, but it did not remove, even though printing key showed the desired cat: Cat key = new Cat("Angie"); ////System.out.println(key); cats.remove(key);

I think since the Cat class has no constructors ,there is no way for us to create and remove Cats by value from the set, so we would have to depend on the iterator to remove a Cat element for us

If you make a copy of cats, run for each on the copy and then use cats.remove(...) within it, then it works.

that is also not removing

then what to do..we cannot create the references again. instead copying. even though we cannot get the elements from the set if we do. then we can assign that reference and remove that object from the set.