SCJP Exception Handling and Java I/O 5

Question 1

Which statement about checked exceptions is correct?

Accepted Answer

They must be caught or declared in the method signature using throws

Answer

Checked exceptions must either be handled with a try-catch or declared with the throws keyword in the method signature.

Question 2

Which class should you use to efficiently write characters to a file using a buffer?

Accepted Answer

BufferedWriter

Answer

BufferedWriter wraps a Writer and uses an internal buffer to reduce I/O operations, improving performance.

Question 3

What does the try-with-resources statement require of the resources it manages?

Accepted Answer

They must implement AutoCloseable

Answer

Resources used in try-with-resources must implement the AutoCloseable interface so close() can be called automatically.

Question 4

Which exception is thrown when the JVM cannot find the definition of a class that is referenced at runtime?

Accepted Answer

NoClassDefFoundError

Answer

NoClassDefFoundError is thrown when a class was present at compile time but cannot be found at runtime.

Question 5

What is the purpose of the ObjectOutputStream class?

Accepted Answer

To serialize Java objects to an output stream

Answer

ObjectOutputStream serializes Java objects (that implement Serializable) by writing them as a byte stream.

SCJP - Sun Certified Java Programmer Practice Test