import java.util.Collection;
import java.util.ArrayList;
import java.util.Iterator;

public class Dog {
    public String name;

    public Dog(String newName){
        name = newName;
    }

    public String toString(){
        return name;
    }

    public void printDog(){
        System.out.printf("%s\n", name);
    }
}


class Dogs {
    public static void main(String[] args) {
         Collection<Dog> pack = new ArrayList<Dog>();
         pack.add(new Dog("Fido"));
         pack.add(new Dog("Spot"));
         pack.add(new Dog("Lucy"));
         System.out.println(pack);

         for (Dog singleDog : pack){
             System.out.println(singleDog.toString());
         }

         for(Iterator<Dog> dogIter = pack.iterator(); dogIter.hasNext();)
         {
             Dog singleDog = dogIter.next();
             if (singleDog.toString().equals("Spot")){
                //1. pack.add(new Dog("Rin-Tin-Tin")); THIS FAILS
                //2. dogIter.add(new Dog("Some new dog")); THIS FAILS
                //3.
                pack.remove(singleDog); //THIS SUCCESSFULLY REMOVES SPOT FROM PACK
                //4. dogIter.remove(singleDog); THIS FAILS
             }

         }

         for (Dog singleDog : pack){
             System.out.println(singleDog);
         }



    }

}
/*
1.  Adding to the collection that we are iterating over results in this error:
Exception in thread "main" java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
    at java.util.ArrayList$Itr.next(Unknown Source)
    at Dogs.main(Dog.java:36)

2.  You cannot add to an iterator

3.  Removing the dog Spot from the collection is allowed, then printing the list after the for loop results in only Fido and Lucy being contained in the list

4.  You cannot remove from an iterator
*/