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.
That's an often made error. You did not initialize your instance variable but have instead created a local variable that shadows the instance field. This local variable is initialized. Simply remove the type declaration of that local variable and you will use the instance variable instead.