Deck 11: Exceptions, and Input Output Operations

Question 1

The purpose of the try and catch blocks is to:

A) throw an exception so a compiler error will not be generated.
B) allow the code to jump over the catch block and continue running.
C) allow the code to handle exceptions so it can continue to run.
D) throw an exception so the catch block can identify the compiler error.

Answer 1

C

Question 2

At run time, if a non-integer is entered, the call to the parseInt method will generate a(n):

A) NullPointerException.
B) ArithmeticException.
C) NumberFormatException.
D) IOException.

Answer 2

C

Question 3

Melanie writes some code with the public class EmailChecker. She uses try and catch blocks to catch thrown exceptions. A user enters this email address: [e-mail]. Which of the following is a likely outcome?

A) The program will catch the misspelling of "lover" and throw an IllegalEmailException.
B) The program will continue executing inside the try block.
C) The attempt to instantiate an object of the Exception class will generate a compiler error.
D) Any of the these would be a likely outcome.

Answer 3

B

Question 4

What is the advantage of declaring a constant as static?

A) It only writes to the file a variable that is declared as transient.
B) It saves disk space.
C) It allows the object to override an exception.
D) All of these are correct.

Question 5

Which of the following is the exception thrown by void writeObject( Object o )?

A) FileNotFoundException
B) ArithmeticException
C) ClassNotFoundException
D) None of these is correct.

Question 6

ObjectOutputStream( OutputStream out ) is a:

A) class.
B) method.
C) constructor.
D) None of these is correct.

Question 7

ObjectOutputStream is a:

A) class.
B) method.
C) constructor.
D) None of these is correct.

Question 8

What makes an instance variable averageGPA a good candidate for being declared as transient?

A) You can easily reproduce its value.
B) Disk space is unimportant.
C) The instance variable will never be 0.
D) None of these is correct.

Question 9

What is a token?

A) A comma that separates data items
B) An individual piece of data
C) A character with special meaning
D) None of these is correct.

Question 10

Which package, introduced with Java 8, provides support for aggregate sequential and parallel operations on a collection of elements?

A) java.io
B) java.util.stream
C) java.lang
D) None of these is correct.

Question 11

PrintWriter( File f) throws a FileNotFoundException.

Question 12

A Stream can easily be constructed from an ArrayList.

Question 13

Large amounts of data reside in which of the following?

A) Data files and databases
B) Data files only
C) Databases only
D) None of these is correct.

Question 14

Which of the following methods in the Exception classes returns void?

A) getMessage( )
B) printStackTrace( )
C) toString( )
D) setModel( )

Question 15

To correct this segment, line 12 should be changed to int n = 1;.
10 public static void main( String [ ] args )
11 {
12 int n;
13 String s = JOptionPane.showInputDialog( null,
14 "Enter an integer" );
15 System.out.println( "You entered " + s );
16
17 try
18 {
19 n = Integer.parseInt( s );
20 System.out.println( "Conversion was successful." );
21 }

Question 16

Your program will work as long as it does not generate compiler errors.

Question 17

FileNotFoundException is related to the Exception class because FileNotFoundException is a subclass of the IOException class, which is a subclass of the Exception class.

Question 18

Sydney accidentally entered .5 instead of 5 in a code asking that she input an integer. She did not get a compiler error, but the program did not run because it generated an exception, which terminated the program.

Question 19

When is it good practice to call the close method?

A) When many files are open, or the same file is open many times
B) When the file is associated with an input or output stream
C) When you have finished processing the data
D) All of these are correct.

Question 20

Professor Simmons had a text file of students in his first-year economics class last semester. This semester, he has all new students. What action should he take to create a useful file for this semester?

A) Write to the existing text file.
B) Append the existing text file.
C) Scan the existing text file.
D) All of these are correct.

Question 21

Replacing the contents of a file with new data is called appending the file.

Question 22

The PrintWriter class is designed for converting basic data types to characters and writing them to a text file.

Question 23

Tokens separate one delimiter from the next.

Question 24

It is preferable to place data items from a file in an ArrayList object instead of a fixed-length array when you do not know how many lines are in the file.

Question 25

Lambda expressions are often used with Streams.

Question 26

We can use a lambda expression as an alternative to implementing a functional interface.

Question 27

Assuming numberStream is a Stream containing doubles, the following code is adding all the doubles in the Stream that are greater than 5.0.
double sum =
numberStream.mapToDouble( item -> Double.parseDouble( item ) )
.filter( price -> price > 5.0 )
.sum( );

Question 28

The String "[1,2,3,4]" is a valid JSON-formatted String.

Question 29

The URL can be used to access a file located remotely (on the Internet).

Question 30

Why it is important to place the catch clause with the EOFException ahead of the catch clause with the IOException?

A) The EOFException catch block will never be reached if it is not first.
B) EOFException is a subclass of IOException.
C) We should arrange the catch blocks to handle the specialized exceptions first, followed by more general exceptions.
D) All of these are correct.

Question 31

When reading objects from a file, until we have reached the end of the file, the condition for the while loop inside a try block is:

A) while ( for ).
B) while ( catch ).
C) for (while).
D) while ( true ).

Question 32

What is a delimiter?

A) A comma, space, or other character that separates tokens
B) A special character with specific functions
C) A code that throws an exception
D) None of these is correct.

Question 33

To read from the file favoriteMovies, what information do you need?

A) A survey of the class to identify their favorite movies
B) How the data were written to the file
C) The number of characters used in the file
D) None of these is correct.

Question 34

Why is it beneficial to be able to extend an Exception class?

A) It overrides an error message with an exception.
B) It allows programmers to associate a specific error message with an exception.
C) It allows coding of the exception without having to code the constructor.
D) It passes the code from the superclass to the derived constructor.

Question 35

Which of the following is the best constructor for reading objects from a file?

A) FileOutputStream( String filename )
B) ObjectOutputStream( OutputStream in )
C) ObjectInputStream( InputStream in )
D) Object readObject( )

Question 36

When we open a file for writing and the file already exists:

A) there will be a compiler error.
B) there will be a runtime error.
C) the file contents will be overwritten.
D) we will be adding data at the end of the file.

Question 37

When we open a file for appending and the file already exists:

A) there will be a compiler error.
B) there will be a runtime error.
C) the file contents will be overwritten.
D) we will be adding data at the end of the file.

Question 38

Which method of the class Scanner do we use to set the delimiter when parsing a string?

A) parse
B) setDelimiter
C) delimiter
D) useDelimiter

Question 39

Which technique is often used when processing a Stream-in particular, calling several methods in order to process the data in the Stream?

A) Looping
B) Iteration
C) Chaining
D) Recursion

Question 40

The filter method of the DoubleStream interface has the following API, DoubleStream filter( DoublePredicate predicate ). What is DoublePredicate?

A) A class
B) An interface
C) A method
D) An instance variable

Question 41

What method of the Collection class can we use to convert an ArrayList to a Stream?

A) convertToStream
B) toStream
C) streamIt
D) stream

Question 42

Which of the following is not using JSON formatting?

A) { 1,2,3,4 }
B) ["A","B","C"]
C) {"M":"Monday","T":"Tuesday"}
D) {"grades":[80,90,100]}

Question 43

The return value for all Scanner methods is boolean.

Question 44

It is possible to code a user-defined exception class.

Question 45

An exception can only be thrown by a method that is not a constructor.

Question 46

The Java package that provides most classes for reading from and writing to files is java.io.

Question 47

The print and println methods of the PrintWriter class allow writing basic data types to a file.

Question 48

The header of a method that potentially generates an exception when called contains the keyword:

A) generates.
B) throws.
C) excepts.

Question 49

To handle an exception, we use a _________ construct.

A) try and catch
B) try and finally
C) catch and finally

Question 50

In which package is the class IOException?

A) java.io
B) java.exception
C) java.util

Question 51

If you try to use the Scanner constructor to open a file that does not exist, what type of exception will be thrown?

A) ScannerException
B) FileNotFoundException
C) FileException
D) NotFoundException

Question 52

When we open a file for writing and the file does not exist, what will happen?

A) There will be a compiler error.
B) There will be a runtime error.
C) The file will be created.

Question 53

When we open a file for appending and the file does not exist, what will happen?

A) There will be a compiler error.
B) There will be a runtime error.
C) The file will be created.

Question 54

To read objects from a file, which class do we use?

A) InputObjectStream
B) ObjectInputStream
C) ObjectStream
D) ObjectInput

Question 55

Which classes can we use to create a Stream from a file in a single statement?

A) Path and File
B) Path and Files
C) Paths and Files
D) Path and Files

Question 56

The superclass of all exception classes is the Exception class.

Question 57

Code that could generate an unchecked exception must be coded with a try and catch block.

Question 58

Code that could generate a checked exception must be coded with a try and catch block or placed inside a method that throws that exception itself.

Question 59

A variable declared inside a try block is still in scope after we exit that try block.

Question 60

It is legal to have more than one catch block to match a try block.

Question 61

Handling a possible illegal operation with a try and catch block will make the code run faster than handling it with a simple if/else construct.

Question 62

Java does not allow objects to be written to or read from a file.

Question 63

When an object is written to a file, transient instance variables of that object are not written to the file.

Question 64

Java provides classes and methods to read data from a remote file (located somewhere on the Internet).

Question 65

Exceptions occur at __________.

Question 66

The class Scanner can be used to __________ a string.

Question 67

For an object of a class to be written to a file, that class must implement the __________ interface.

Question 68

The __________ class encapsulates the concept of a Uniform Resource Locator.

Question 69

__________ formatting is made up of two data structures: key/value pairs and arrays.

Question 70

Because the readObject method returns a generic object, what must the returned object be?

Question 71

Tyler wrote a code that includes multiple catch blocks to catch files not found and characters that are not integers. Predict what will happen if a user enters an invalid file and also enters a 1.5 for the integer.

Question 72

How can the methods of the Exception class be useful?

Question 73

When we read objects from a file using the readObject method, what happens when the end of the file is reached?

Question 74

You want to handle a suspected exception in your program, so you insert the following try and catch blocks. However, the program generated a compiler error. Improve this program to avoid that problem.
1
2 try
3 {
4 n = Integer.parseInt( s );
5 System.out.println( "Conversion was successful." );
6 catch ( NumberFormatException nfe )
7 System.out.println( "Sorry. incompatible data." );
8 System.out.println( "\nOutput from getMessage: \n"
9 + nfe.getMessage( ) );
10
11 System.out.println( "\nOutput from toString: \n"
12 + nfe.toString( ) );
13 System.out.println( "\nOutput from printStackTrace: " );
14 nfe.printStackTrace( );
15 }

Question 75

Suppose you write a program using the Scanner class to read data from a text file. The file is not found, but the code instantiating the Scanner was inside a try block. Predict what will happen, and explain why this is advantageous.

Question 76

Evaluate what will happen if you run a program that attempts integer division by 0.

Question 77

What is the purpose of the following code segment?
13 String flightRecord1 = "AA123,BWI,SFO,235,239.5";
14 Scanner parse = new Scanner( flightRecord1 );
15 // set the delimiter to a comma
16 parse.useDelimiter( "," );