A.s.defaultReadObject（）；B.this = s.defaultReadObject（）；……

单项选择题Given that the current directory is empty， and that the user has read and write permissions， and the following： Which statement is true？（）

A.Compilation fails.
B.The file system has a new empty directory named dir.
C.The file system has a new empty directory named newDir.
D.The file system has a directory named dir， containing a file f1.txt.
E.The file system has a directory named newDir， containing a file f1.txt.

单项选择题Whichcapabilityexistsonlyinjava.io.BufferedWriter？（）

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？（）

A.restore 400
B.restore 403
C.restore 453
D.Compilation fails.
E.An exception is thrown at runtime.

多项选择题Which two statements are true if a NullPointerException is thrown on line 3 of class C？（）

A.The application will crash.
B.The code on line 29 will be executed.
C.The code on line 5 of class A will execute.
D.The code on line 5 of class B will execute.
E.The exception will be propagated back to line 27.

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？（）

A.assert value == null；
B.assert value != null ： "value is null"；
C.if （value == null）{    throw new AssertionException（"value is null"）；   }
D.if （value == null）{    throw new IllegalArgumentException（"value is null"）；   }