This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
hi Phil ,
here is the code that it should look like
what is happening is that the the HashSet overrides the hashcode() and equals() method ,so if you try to put duplicate elements in a HashSet it would be considered as a single value and only one of them will exist ,therefore when we delete 1 there is only one element left and that is 2 and if we remove that also we get size of set as zero,it is one of the reasons why set is different from lists which can contain duplicate elements.