OCPJP Simulation Test 78

78

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Question: Given Queue<?> queue = new ArrayBlockingQueue<OutputStream>(10), what are the following code compiles?

Choice:
A. queue.add(new OutputStream());
B. queue.add(new FileOutputStream());
C. queue.add(new FileWriter());
D. queue.add(new BufferedOutputStream());
E. queue.add(new ObjectOutputStream());
F. queue.add(new BufferedWriter());
G. queue.add(new FilterInputStream());
H. None of the above



Next Question

Answer: H

Explain: collections declared with unbounded wildcards can not be modified.

Study:  Create and use a generic class 
Use BufferedReader, BufferedWriter, File, FileReader, FileWriter, FileInputStream, FileOutputStream, ObjectOutputStream, ObjectInputStream, and PrintWriter in the java.iopackage.