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.
<?> is commonly refereed as wild card and there are three in nature
<?> -- you can assign anything e.g List<String> or List<Integer>
<? extends Object > -- you can assign anything which is either Object of subclass of Object
<? super MyClass> -- you can assign anything which is either MyClass or super class of MyClass.