Beginning Java with NetBeans: Chapter 16

How to work with exceptions

MULTIPLE CHOICE [Answers are in tables delete all but the correct answers cell]

1. Unchecked exceptions are the only exceptions derived from which class?

a.	Exception	c.	RuntimeException
b.	Error	d.	Throwable

2. Which of the following classes define exceptions that can occur in a Java application?

a.	ArithmeticException	d.	all of the above
b.	NumberFormatException	e.	none of the above
c.	NullPointerException

3. What is the maximum number of finally blocks that you can code?

a.	One for each exception	c.	As many as needed
b.	One for each try block	d.	10

4. The try-with-resources statement doesnt need a finally clause because it

a.	uses a multi-catch block to catch all exceptions
b.	implements the AutoCloseable interface
c.	automatically closes all declared resources
d.	catches all exception that are thrown when you try to close a resource

Code example 16-1

Scanner sc = new Scanner(System.in);

System.out.print("Enter a number less than 10: ");

int num;

while (true) {

try {

num = Integer.parseInt(sc.nextLine());

if (num >= 10) {

System.out.print("Too big. Try again: ");

continue;

}

break;

} catch(NumberFormatException e) {

System.out.print("Invalid number. Try again: ");

}

}

5. (Refer to code example 16-1.) What happens if the user enters 11 at the prompt?

a.	A NumberFormatException is thrown, execution jumps to the catch block, and a message that says Invalid number. Try again: is printed to the console.
b.	A message that says Too big. Try again: is printed to the console and execution jumps to the top of the loop.
c.	A NumberFormatException is not thrown, the entry is stored in a variable, and execution jumps to the top of the loop.
d.	A NumberFormatException is not thrown, the entry is stored in a variable, and execution jumps out of the loop.

6. (Refer to code example 16-1.) What happens if the user enters 5 at the prompt?

a.	A NumberFormatException is thrown, execution jumps to the catch block, and a message that says Invalid number is printed to the console.
b.	A message that says Too big is printed to the console and execution jumps to the top of the loop.
c.	A NumberFormatException is not thrown, the entry is stored in a variable, and execution jumps to the top of the loop.
d.	A NumberFormatException is not thrown, the entry is stored in a variable, and execution jumps out of the loop.

7. (Refer to code example 16-1.) What happens if the user enters abc at the prompt?

a.	A NumberFormatException is thrown, execution jumps to the catch block, and a message that says Invalid number is printed to the console.
b.	A message that says Too big is printed to the console and execution jumps to the top of the loop.
c.	A NumberFormatException is not thrown, the entry is stored in a variable, and execution jumps to the top of the loop.
d.	A NumberFormatException is not thrown, the entry is stored in a variable, and execution jumps out of the loop.

Code example 16-2

public static void connectAndOpenDB() {

try {

StudentDB.connect(); //can throw a ClassNotFoundException

StudentDB.open(); //can throw an SQLException

} catch(ClassNotFoundException | SQLException e) {

System.out.println(e.getMessage());

}

System.out.println("Connected and opened.");

}

8. (Refer to code example 16-2.) Which of the following is true if an SQLException is thrown?

a.	A ClassNotFoundException was not thrown.
b.	A ClassNotFoundException was also thrown.
c.	Neither of the statements that use the println method were called.
d.	The println method after the catch clause was not called.

9. When coding catch blocks, you should always code them in what order?

a.	Most specific exception to least specific
b.	Least specific exception to most specific
c.	Most important exception to least important
d.	Order doesnt matter

10. A multi-catch block allows you to use

a.	multiple catch blocks to handle multiple exceptions that are at the same level in the exception hierarchy
b.	multiple catch blocks to handle exceptions that are at different levels in the exception hierarchy
c.	a single catch block to handle multiple exceptions that are at the same level in the exception hierarchy
d.	a single catch block to handle multiple exceptions that are at different levels in the exception hierarchy

11. If the following code is located in a method named readData, what must a method that calls readData do?

try (RandomAccessFile in = new RandomAccessFile("f.dat", "r")) {

long length = in.length();

} catch(FileNotFoundException fnfe) {

System.err.println("file.dat doesn't exist");

} catch(IOException ioe) {

System.err.println("error in length method of RAF");

throw ioe;

}

a.	Throw or handle a FileNotFoundException
b.	Throw or handle an IOException
c.	Throw or handle a FileNotFoundException and an IOException
d.	Doesnt have to throw or handle any exceptions

12. Exception chaining lets you

a.	handle more than one exception in the same method
b.	save the details of an exception in a custom exception
c.	create a list of methods in the reverse order in which they were called
d.	keep a log of the exceptions that occur as an application executes

13. In the code that follows, which method handles the IOException?

public static void main(String[] args) {

methodA();

}

private static void methodA() throws IOException {

methodB();

}

private static void methodB() throws IOException {

throw new IOException();

}

a.	methodA	c.	main
b.	methodB	d.	none

14. To make the code that follows compile, what should the declaration of the getStudent method be?

public void getStudent() {

readGrades();

}

public void readGrades() throws IOException {

boolean gradesAvailable = true;

if (gradesAvailable == false) {

throw new IOException();

}

}

a.	public void getStudent(){...}
b.	public static void getStudent(){...}
c.	public void getStudent() throws IOException{...}
d.	public void getStudent() throw new IOException(){...}

15. What is printed to the console if a FileNotFoundException occurs in the try block that follows?

try {

file = new RandomAccessFile(fileName, "r");

validName = true;

} catch(FileNotFoundException e) {

System.out.println("FileNotFoundException.");

} catch(IOException e) {

System.out.println("IOException");

} finally {

System.out.println("Finally");

}

a.	FileNotFoundException
b.	FileNotFoundException and IOException
c.	FileNotFoundException and Finally
d.	Finally

16. When is an exception swallowed?

a.	When an exception handler isnt coded for it
b.	When the exception handler doesnt contain any code
c.	When it isnt caught or thrown
d.	When its caught by an exception handler for a more general exception

COMPLETION

17. All exception classes are derived from the ____________ class.

18. Exceptions that you must handle before you can compile your code are called ____________ exceptions.

19. Code thats executed in response to an exception is called a/an ____________________.

20. Java locates the code that handles an exception by searching through the ________________.

21. To keep from losing debugging information when you throw a custom exception, you should use a feature called exception ____________________.