1. Which line completes this code fragment to define a text file named txtfile f

Question

1. Which line completes this code fragment to define a text file named txtfile for reading?

____________________________________________________

Reader scan = new Reader(new File("txtfile"));

FileReader scan = new File("txtfile");

Scanner scan = new Scanner(System.in);

Scanner scan = new Scanner(new File("txtfile"));

1 points   

QUESTION 2

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

In order to return a char.

In order to read binary data.

To read data from a file.

To check for end of file.

1 points   

QUESTION 3

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?

It will be 133.

It will be -133.

It will be some negative value.

It will be some positive value.

1 points   

QUESTION 4

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?

cvkkt

atiir

bujjs

happy

1 points   

QUESTION 5

Which of these classes access sequences of characters?

I readers

II writers

III streams

I

II

I and II

II and III

1 points   

QUESTION 6

Which of the following cannot be serialized?

I ArrayList<String>

II String

III  Integer

I

II and III

III

All can be serialized

1 points   

QUESTION 7

In which of the following modes can a RandomAccessFiles be opened?

I “r”

II “rw”

III “w”

I

II

I and II

I and III

1 points   

QUESTION 8

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

Stream

Serializable

SequentialAccessFile

RandomAccessFile

1 points   

QUESTION 9

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 b) {  __________ }

return (b + key);

return (b + key % 26);

return (b + key) % 256);

return (b + 26 % key);

1 points   

QUESTION 10

What type is returned from a call to the ObjectInputStream.readObject method when reading a String from an object stream?

Object

String

char

ObjectStream

1 points   

QUESTION 11

How many methods are required to implement the Serializable interface?

3

2

1

0

1 points   

QUESTION 12

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

RandomAccessFile

FileWriter

FileInputStream

Scanner

1 points   

QUESTION 13

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

1

2

4

8

1 points   

QUESTION 14

Which is not a method in the RandomAccessFile class?

getFilePointer

seek

scan

length

1 points   

QUESTION 15

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

the file pointer is of type _______.

double

byte

int

long

1 points   

QUESTION 16

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

int

char

String

byte

1 points   

QUESTION 17

If we want to write objects to a file, what type of object should be passed to the ObjectOutputStream constructor?

ObjectStream

FileStream

FileOutputStream

ObjectInputStream

1 points   

QUESTION 18

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

PrintWriter out = new PrintWriter();

PrintWriter out = new PrintWriter("output.txt");

FileReader reader = new FileReader("input.txt");

Scanner in = new Scanner(reader);

1 points   

QUESTION 19

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

FileReader

PrintWriter

OutputStreamWriter

ObjectOutputStream

1 points   

QUESTION 20

Streams access sequences of ____.

characters

files

strings

bytes

Reader scan = new Reader(new File("txtfile"));

FileReader scan = new File("txtfile");

Scanner scan = new Scanner(System.in);

Scanner scan = new Scanner(new File("txtfile"));

Explanation / Answer

Answer:

1. Scanner scan = new Scanner(System.in);

The above line completes the code to define a textfile.

2.   To read data from a file.

it overrides to implement all the methods in the program.

3.   

4. bujjs

using caesar cipher,

e->b, x-u, m->j, v->s

Hence, bujjs.

5. I and II

Readers and writers classes access sequence of characters.

6. All can be serialized

Yes, serialization not only stores the object, but also the states of the object.

7. I and II

The mode argument can be either "r" for read only or "rw" can be read and written to.

8. RandomAccessFile

random access files, you can acess the files directly and quickly without searching through all the other records first.

9. return (b + key) % 256);

10. ObjectStream

11. 0

12. FileWriter

FileWriter  is used for input of text data from a file.

18. PrintWriter out = new PrintWriter("output.txt");

19. PrintWriter

20. Characters

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