线程“AWT-EventQueue-0”java.lang中的异常。NullPointerException Java

I keep getting this error in my console, however there's no error in my coding when I look over it. It also keeps opening up the exact same JOptionPanes when I don't want it to open up. After the loops supposedly finish, the JOptionPane reopens and goes through asking the user to input values for the Bingo Card. However, it still fills and makes a BingoCard after the first JOptionPane loops are done. I keep getting this error in my console, howeve