单项选择题
A.Closing an open stream.
B.Flushing an open stream.
C.Writing to an open stream.
D.Writing a line separator to an open stream.
单项选择题 Assuming that the serializeBanana() and the deserializeBanana() methods will correctly use Java serialization and given： What is the result？（）
多项选择题 Which two statements are true if a NullPointerException is thrown on line 3 of class C？（）
单项选择题 Given a method that must ensure that its parameter is not null： What， inserted at line 12， is the appropriate way to handle a null value？（）