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.
because the compiler knows that an instance of a Ticker cannot possibly be a string - it can see that String extends Object and Ticker extends Component which itself extends Object. so a Ticker can not be an instance of String.