Deck 19: Streams and Binary Inputoutput

Question 1

Which line completes this code fragment so it creates a text file called "mychars.txt" and writes the characters 'A', 'B', and 'C' into the file?
_____________________
Fw)write('A');
Fw)write('B');
Fw)write('C');

A) PrintWriter fw = new PrintWriter("mychars.txt");
B) FileOutputStream fw = new FileOutputStream("mychars.txt");
C) File fw = new File("mychars.txt");
D) PrintStream fw = new PrintStream("mychars.txt");

Answer 1

A

Question 2

You use _________ and FileOutputStream objects to write data to a disk file in text or binary form respectively.

A) FileReader
B) PrintWriter
C) OutputStreamWriter
D) ObjectOutputStream

Answer 2

B

Question 3

The ____ class is used when writing text files.

A) PrintWriter
B) InputStream
C) JFileChooser
D) Serializable

Answer 3

A

Question 4

Which class is used for input of binary data?

A) Reader
B) Writer
C) InputStream
D) OutputStream

Question 5

Which of the following reads binary data from a disk file?

A) PrintWriter text = new PrintWriter("input.bin");
B) FileReader text = new FileReader("input.bin");
C) FileInputStream inputStream = new FileInputStream("input.bin");
D) FileWriter text = new FileWriter("input.bin");

Question 6

Which class is used for input of text data from a file?

A) RandomAccessFile
B) FileWriter
C) FileInputStream
D) Scanner

Question 7

In Java, the simplest mechanism for reading text is to use the ____ class.

A) ReadWrite
B) Scanner
C) PrintWriter
D) Serializable

Question 8

Which class is used for input of text data?

A) Reader
B) Writer
C) InputStream
D) OutputStream

Question 9

Which is an advantage of storing numbers in binary format?
I fast access
II less storage needed
III easy to read in a text editor

A) I
B) III
C) I and II
D) I and III

Question 10

Readers and writers access sequences of ____.

A) bytes
B) characters
C) files
D) streams

Question 11

Which file storage method is in human-readable form?

A) binary
B) object
C) text
D) byte

Question 12

Which line completes this code fragment to define a text file named txtfile for reading?
____________________________________________________
String line = scan.nextLine();

A) Reader scan = new Reader(new File("txtfile"));
B) FileReader scan = new File("txtfile");
C) Scanner scan = new Scanner(System.in);
D) Scanner scan = new Scanner(new File("txtfile"));

Question 13

When constructing a Scanner from a File object, the Scanner automatically constructs a ___________.

A) InputStream
B) FileInputStream
C) FileReader
D) PrintWriter

Question 14

If you store information in binary form, as a sequence of bytes, you will use the ____ class(es) and their subclasses.

A) InputStream and OutputStream
B) Serializable
C) PrintWriter
D) Reader and Writer

Question 15

In text format, data items are represented in human-readable form, as a sequence of ____________________.

A) integers
B) bytes
C) characters
D) strings

Question 16

To read text data from a disk file, you should create a(n) ____________________ object.

A) Scanner
B) PrintWriter
C) InputStream
D) OutputStream

Question 17

Streams access sequences of ____.

A) characters
B) files
C) strings
D) bytes

Question 18

Which of the following statements enables you to write output to a text file?

A) PrintWriter out = new PrintWriter();
B) PrintWriter out = new PrintWriter("output.txt");
C) FileReader reader = new FileReader("input.txt");
D) Scanner in = new Scanner(reader);

Question 19

Which file storage method stores data in bytes?

A) binary
B) object
C) text
D) byte

Question 20

A byte is composed of ____ bits and can denote ____ values.

A) 2, 19
B) 4, 256
C) 8, 256
D) 8, 1024

Question 21

If we read a byte and the value represents an international character equal to 133 using an InputStream object, what is true about the int value we will read?

A) It will be 133.
B) It will be -133.
C) It will be some negative value.
D) It will be some positive value.

Question 22

Caesar cipher uses a shift of each character by a key with a value between 1 and 255. An a with a shift equal to 3 becomes a d. A z would become a c, wrapping around the alphabet. Which is the decryption of exmmv for a key = -3?

A) cvkkt
B) atiir
C) bujjs
D) happy

Question 23

What is the highest value for a signed (negative and positive) byte?

A) 127
B) 128
C) 255
D) 256

Question 24

How many bytes does the read method in the FileInputStream class actually get from the file?

A) 1
B) 2
C) 4
D) 8

Question 25

How many bytes does the read method in the InputStream class get from the file?

A) 1
B) 2
C) 4
D) 8

Question 26

How many bytes does the read method in the FileInputStream class actually return to the program call?

A) 1
B) 2
C) 4
D) 8

Question 27

You cannot read a(n) ____________________ file with a text editor.

A) random
B) serial
C) sequential
D) binary

Question 28

Which statement is true regarding the following code, assuming reader is a FileInputStream object?
Char ch = (char) reader.read();
I you cannot determine if you have reached the end of input
II this code will throw an exception if we are at the end of input
III read returns an int, so the cast is illegal

A) I
B) II
C) III
D) I and II

Question 29

Caesar cipher uses a shift of each character by a key with a value between 1 and 255. An a with a shift equal to 3 becomes a d. A z would become a c, wrapping around the alphabet. Which key should you use to encrypt picture into mfzqrob?

A) 3
B) 19
C) -3
D) -19

Question 30

Caesar cipher uses a shift of each character by a key with a value between 1 and 255. An a with a shift equal to 3 becomes a d. For the decrypt method below, select the correct body. Assume the key shift property is accessible to the method.
Public int decrypt(int

A) return (b + key);
B) { ________ }
B) return (b - key % 26);
C) return (b - key) % 256);
D) return (b - key);

Question 31

What is the lowest value for a signed (negative and positive) byte?

A) -127
B) -128
C) -255
D) -256

Question 32

What is the result of the following code?
Reader reader = … ; // connect to a file
Char ch = reader.read();

A) compiler error
B) 1 byte is read from the file
C) 2 bytes are read from the file
D) 4 bytes are read from the file

Question 33

If you want to process text data from a file, which keyword do you look for in classes that specialize in doing that?

A) text
B) serializable
C) binary
D) reader

Question 34

The FileInputStream read method reads binary data. What type is actually returned from a call to read?

A) int
B) char
C) String
D) byte

Question 35

Caesar cipher uses a shift of each character by a key with a value between 1 and 255. An a with a shift equal to 3 becomes a d. A z would become a c, wrapping around the alphabet. Which is the encryption of shadow for a key = 3?

A) ukdgry
B) vkdgrz
C) adowsha
D) vjegrz

Question 36

Caesar cipher uses a shift of each character by a key with a value between 1 and 255. An a with a shift equal to 3 becomes a d. For the encrypt method below, select the correct body. Assume the key shift property is accessible to the method.
Public int encrypt(int

A) return (b + key);
B) { __________ }
B) return (b + key % 26);
C) return (b + key) % 256);
D) return (b + 26 % key);

Question 37

Caesar cipher uses a shift of each character by a key with a value between 1 and 255. An a with a shift equal to 3 becomes a d. A z would become a c, wrapping around the alphabet. Which is the encryption of picture for a key = -3?

A) erutcip
B) ngahspc
C) mfzqrob
D) urepict

Question 38

How many bytes does the read method in the InputStream class actually return to the program call?

A) 1
B) 2
C) 4
D) 8

Question 39

If you write a simple Student class, what must you do in order to write Student objects to an ObjectOutputStream?

A) Code a write method.
B) Make all class variables primitive.
C) Implement Serializable.
D) Implement Streamable.

Question 40

What is returned by the read method when a FileInputStream has reached the end of the file?

A) -1
B) -2
C) '\n'
D) 0

Question 41

Which of the following classes are used with data in binary form?
I FileInputStream
II FileReader
III RandomAccessFile

A) I
B) I and II
C) I and III
D) II and III

Question 42

Which is not a method available in the RandomAccessFile class?

A) open
B) readInt
C) readDouble
D) close

Question 43

The ______ method returns an integer, either -1 (at the end of the file) or a byte between 0 and 255.

A) RandomAccessFile.seek
B) InputStream.read
C) Scanner.next
D) Reader.length

Question 44

In Java, the byte type is a(n) ____ type.

A) positive
B) signed
C) negative
D) unsigned

Question 45

Which method in the RandomAccessFile class provides for random access?

A) move
B) seek
C) goto
D) offset

Question 46

In Java, you use a(n) ____________ object to access a file and move its file pointer.

A) Stream
B) Serializable
C) SequentialAccessFile
D) RandomAccessFile

Question 47

Given a RandomAccessFile that stores a set of records of class MyData, each needing MyData.RECORD_SIZE bytes for storage, which expression gets the offset to the beginning of the 25^th record?

A) MyData.RECORD_SIZE * 25
B) MyData.RECORD_SIZE * 24
C) MyData.RECORD_SIZE++
D) MyData.RECORD_SIZE + 25

Question 48

Assume we have a RandomAccessFile object, file, which stores a set of records of class MyData, each needing MyData.RECORD_SIZE bytes for storage. Which expression calculates the number of records in the file?

A) MyData.RECORD_SIZE * file.length()
B) MyData.RECORD_SIZE + file.getFilePointer()
C) file.seek(0L) / MyData.RECORD_SIZE
D) file.length() / MyData.RECORD_SIZE

Question 49

The values of the byte type range from ____ to ____.

A) 0, 255
B) 0, 256
C) -128, 128
D) -128, 127

Question 50

Assume we have a RandomAccessFile object, file, which stores a set of records of class MyData, each needing MyData.RECORD_SIZE bytes for storage. If the file pointer is currently on the 24^th record, which expression gets to the offset of the beginning of the 25^th record?

A) MyData.RECORD_SIZE + 1
B) MyData.RECORD_SIZE + file.getFilePointer()
C) MyData.RECORD_SIZE * 2
D) file.getFilePointer()

Question 51

Why does FileInputStream override the read method from its superclass InputStream?

A) In order to return a char.
B) In order to read binary data.
C) To read data from a file.
D) To check for end of file.

Question 52

Assume we have a RandomAccessFile object, file, that stores a set of records of class MyData. The size of each record is MyData.RECORD_SIZE. Assume MyData has read and write methods both of which take a RandomAccessFile as an argument. Method write writes the object at the current location. Method read reads the record from current location of the file into the object. If we are currently at the beginning of the 1^st record, which code correctly modifies the 2^nd record by changing its color to Color.red through the setColor method?

A) file.seek(MyData.RECORD_SIZE);
MyData.read(file);
MyData.setColor(Color.red);
File.seek(MyData.RECORD_SIZE);
MyData.write(file);
B) myData.read(file);
MyData.read(file);
MyData.setColor(Color.red);
MyData.write(file);
C) myData.read(file);
MyData.setColor(Color.red);
File.seek(file.getFilePointer() + MyData.RECORD_SIZE);
MyData.write(file);
D) long loc = file.getFilePointer();
MyData.read(file);
MyData.setColor(Color.red);
File.seek(loc);
MyData.write(file);

Question 53

Which is not a method in the RandomAccessFile class?

A) getFilePointer
B) seek
C) scan
D) length

Question 54

In which of the following modes can a RandomAccessFiles be opened?
I "r"
II "rw"
III "w"

A) I
B) II
C) I and II
D) I and III

Question 55

You would need a Caesar cipher with a shift of __________ to decrypt the following text, T U V W X Y Z A B C D E F G H I J K L M N O P Q R S, so that it reads A B C D E F G H I J K L M N O P Q R S T U V W X Y Z.

A) 7
B) 20
C) 19
D) -19

Question 56

What do we call the measure in bytes of the file pointer from the beginning of a RandomAccessFile?

A) latency
B) offset
C) size
D) seek

Question 57

Assume we have a RandomAccessFile object, file, which stores a set of records of class MyData. The size of each record is MyData.RECORD_SIZE. Assume MyData has read and write methods, both of which take a RandomAccessFile as an argument. Method write writes the object at the current location. Method read reads the record from current location of the file into the object. If we are currently at the beginning of the 25^th record, which code correctly modifies the 25^th record by changing its color to Color.yellow through the setColor method?

A) myData.read(file);
MyData.setColor(Color.yellow);
MyData.write(file);
B) myData.read(file);
MyData.setColor(Color.yellow);
File.seek(file.getFilePointer());
MyData.write(file);
C) myData.read(file);
MyData.setColor(Color.yellow);
File.seek(file.getFilePointer() + MyData.RECORD_SIZE);
MyData.write(file);
D) long loc = file.getFilePointer();
MyData.read(file);
MyData.setColor(Color.yellow);
File.seek(loc);
MyData.write(file);

Question 58

Which code stores an array buttonArray of JButton objects in a file named buttonFile? We ignore exceptions in this problem.

A) ObjectStream os = new ObjectStream(new FileStream("buttonFile");
Os)writeObject(buttonArray);
B) ObjectOutputStream oos = new ObjectOutputStream(
New FileOutputStream("buttonFile");
Oos)writeObject(buttonArray);
C) ObjectOutputStream oos = new ObjectOutputStream(
New FileOutputStream("buttonFile");
Oos)writeObject(buttonArray[0]);
D) ObjectOutputStream oos = new ObjectOutputStream("buttonFile");
Oos)writeObject(buttonArray);

Question 59

In ____________ file access, the file is processed starting from the beginning.

A) random
B) serial
C) sequential
D) binary

Question 60

__________ access allows file access at arbitrary locations, without first reading the bytes preceding the access location.

A) Random
B) Serial
C) Sequential
D) Binary

Question 61

Objects saved to an object stream must belong to classes that:

A) implement the Serializable interface.
B) are RandomAccessFile objects.
C) are abstract.
D) implement the ObjectInputStream interface.

Question 62

Objects are saved in ___________ format in object streams.

A) binary
B) character
C) stream
D) integer

Question 63

Which methods are not in the Serializable interface?
I readObject
II writeObject
III serializeObject

A) I
B) I and II
C) II and III
D) I, II, and III

Question 64

When storing numbers in a file with fixed record sizes, it is easier to store them in __________ format.

A) character
B) text
C) binary
D) serializable

Question 65

Based on the code below, the statement that would move the file pointer to byte n counted from the beginning of the file is ___________________.
RandomAccessFile test = new RandomAccessFile("record.bat", "r");

A) test.getFilePointer(n);
B) test.getFilePointer();
C) test.seek(n);
D) test.length() - n;

Question 66

A file pointer is a position in a random access file. Because files can be very large,
The file pointer is of type _______.

A) double
B) byte
C) int
D) long

Question 67

Which interface allows classes to be written to an ObjectOutputStream?

A) Objective
B) Streaming
C) Serializable
D) Objectifiable

Question 68

How many methods are required to implement the Serializable interface?

A) 3
B) 2
C) 1
D) 0

Question 69

The readDouble and writeDouble methods of the RandomAccessFile class, process double precision floating-point numbers as ____ quantities.

A) two-byte
B) four-byte
C) eight-byte
D) ten-byte

Question 70

If serializing object obj requires 12 bytes, how many bytes are required to serialize obj 3 times?

A) 12 bytes plus 3 serial numbers of obj
B) 36 bytes
C) 12 bytes
D) 12 bytes plus 2 serial numbers of obj

Question 71

Which method moves the file pointer in a RandomAccessFile?

A) seek
B) length
C) getFilePointer
D) close

Question 72

Which code moves the file pointer to the middle of a RandomAccessFile object, file?

A) file.seek(file.length() / 2)
B) file.seek(file.length())
C) file.seek(0L)
D) file.seek(file.getFilePointer() / 2)

Question 73

Which of the following cannot be serialized?
I ArrayList
II String
III Integer

A) I
B) II and III
C) III
D) All can be serialized

Question 74

Which of these classes access sequences of characters?
I readers
II writers
III streams

A) I
B) II
C) I and II
D) II and III

Question 75

Use a ____ object to access a file and move a file pointer.

A) Random
B) RandomAccess
C) RandomAccessFile
D) System.in

Question 76

The two IO classes used for serialization are _______ and ________.

A) Reader, Writer
B) ObjectInputStream, ObjectOutputStream
C) Scanner, PrintWriter
D) FileReader, FileWriter

Question 77

Every object is assigned a serial number on the stream. What might be the result if the same object is saved twice?

A) The object will have two serial numbers.
B) Only the serial number is written out the second time.
C) A performance decrease.
D) Running out of serial numbers.

Question 78

The readInt and writeInt methods of the RandomAccessFile class read and write integers as ____ quantities.

A) two-byte
B) four-byte
C) six-byte
D) eight-byte

Question 79

Which of the following classes are related through inheritance?
I InputStream
II InputStreamReader
III ObjectInputStream

A) I and II
B) I and III
C) II and III
D) I, II and III

Question 80

In which package are most classes for file processing found?

A) java.file
B) java.inputoutput
C) java.io
D) java.stream