This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori 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.