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.
Please learn to UseCodeTags (<-click) when posting source code.
There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
Joined: Feb 07, 2005
I believe your issue is shadowing. You have the three arrays declared as instance variables. But in the init method, you create local variables with the same name. The instance variables are still null.