My Treeset only adds 1 class object

Question

I\'m trying to add the below book objects to a TreeSet. However, when I debug the code, it says that the set has a size of 1 and only contains the first object added (book1). Wh

Answer 1

All books are equal to one another (evident by returning 0). A Set cannot contain duplicates, so that's why only one (the first Book) is ever added

@Override
public int compareTo(Book o) {
    // TODO Auto-generated method stub
    return 0;
}  

You need to fill in the details of the method. Negative numbers say this book is less than o, vice versa for positive numbers