Question 1

In which of the following modes can a RandomAccessFile be opened?
i.r
II.rw
III.w
A)I and III only
B)I only
C)I and II only
D)II only

Accepted Answer

A RandomAccessFile can be opened in two modes:
I. "r": read-only mode
II. "rw": read-write mode

Therefore, options A, B, and D are incorrect. Option C is correct as it includes both acceptable modes. Option I only allows reading, and III only allows writing, which are not the only valid options, so they are incorrect.

Question 2

Which code moves the file pointer to the middle of a RandomAccessFile object, file?
A)file.seek(file.getFilePointer() / 2)
B)file.seek(file.length() / 2)
C)file.seek(0L)
D)file.seek(file.length())

Accepted Answer

The method file.length() returns the total length of the file in bytes. We want to move the pointer to the middle of the file, so we divide the total length by 2 to get the midpoint. Then, we use the method file.seek() to move the pointer to this position, which is the correct implementation in choice B.

Question 3

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 24th record, which expression represents the offset to the beginning of the 25th record?
A)MyData.RECORD_SIZE * 2
B)MyData.RECORD_SIZE + file.getFilePointer()
C)MyData.RECORD_SIZE + 1
D)file.getFilePointer()

Accepted Answer

The offset to the beginning of the 25th record would be the size of one record plus the current position of the file pointer, which is the end of the 24th record. Therefore, the correct expression would be MyData.RECORD_SIZE + file.getFilePointer().

Question 4

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

Accepted Answer

To get the offset to the beginning of the 25th record, we need to calculate the number of bytes needed to store the first 24 records and add that to the beginning of the file. Therefore, the correct expression is MyData.RECORD_SIZE * 24, which gives the total number of bytes needed for the first 24 records. Adding MyData.RECORD_SIZE to this expression would give the offset to the start of the 2nd record, not the 25th record. Choice A would also give the offset to the start of the 25th record. Choice C increments the value of MyData.RECORD_SIZE, which is not useful for calculating the offset.

Question 5

Which of the following classes are used with data in binary form?
i.FileInputStream
II.FileReader
III.RandomAccessFile
A)I and III only
B)I and II only
C)II and III only
D)I only

Accepted Answer

FileInputStream and RandomAccessFile are used with data in binary form. FileInputStream is used for reading binary data from a file, while RandomAccessFile is used for reading and writing binary data to a file. FileReader, on the other hand, is used for reading character data from a file. Therefore, options II and III are not the best choices for data in binary form.

Question 6

Which is NOT a method in the RandomAccessFile class?
A)seek
B)length
C)getFilePointer
D)scan

Accepted Answer

The RandomAccessFile class does not have a method named "scan". The other three methods (seek, length, and getFilePointer) are all methods of the RandomAccessFile class.

Question 7

__________ access allows file access at arbitrary locations, without first reading the bytes preceding the access location.
A)Sequential
B)Serial
C)Random
D)Binary

Accepted Answer

Random access allows the direct access of files at any location without having to read through the preceding data. Sequential access processing involves reading and processing data sequentially, one record after another, from the beginning to the end of the file. Serial access refers to the transfer of data sequentially, one bit after another, through a communication channel. Binary refers to a number system that uses only two digits (0 and 1) and is not directly related to file access methods.

Question 8

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

Accepted Answer

To calculate the number of records in the file, we need to divide the total length of the file by the size of each record. Therefore, the correct expression is file.length() / MyData.RECORD_SIZE.

Question 9

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 25th record, which code correctly modifies the 25th record by changing its color to Color.yellow through the setColor method? 
A) 
B) 
C) 
D)

Accepted Answer

The answer of Assume we have a RandomAccessFile object, file,...

Question 10

A file pointer is a position in a random access file.Because files can be very large, the file pointer is of type _______.
A)int
B)double
C)long
D)byte

Accepted Answer

The file pointer needs to be able to store a large and potentially negative value, so the best choice is a long integer, represented by the "long" data type. This allows the file pointer to properly navigate through large files.

Question 11

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 1st record, which code correctly modifies the 2nd record by changing its color to Color.red through the setColor method?

A) 
B) 
C) 
D)

Accepted Answer

The answer of Assume we have a RandomAccessFile object, file,...

Question 12

Which method in the RandomAccessFile class provides for random access?
A)goto
B)offset
C)seek
D)move

Accepted Answer

The seek method in the RandomAccessFile class provides for random access by moving the file pointer to a specific position in the file. It allows for both reading and writing at any position in the file. The other options (goto, offset, and move) are not methods in the RandomAccessFile class and do not provide for random access.

Question 13

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

Accepted Answer

The method "seek(n)" in the "RandomAccessFile" class moves the file pointer to byte n counted from the beginning of the file.

Question 14

The readInt and writeInt methods of the RandomAccessFile class read and write integers as ____ quantities.
A)two-byte
B)four-byte
C)eight-byte
D)six-byte

Accepted Answer

The readInt and writeInt methods of the RandomAccessFile class read and write four-byte integers.

Question 15

When storing numbers in a file with fixed record sizes, it is easier to store them in __________ format.
A)character
B)binary
C)serializable
D)text

Accepted Answer

Storing numbers in binary format takes up less space and allows for easier processing and manipulation of the data compared to storing them as characters or text. Additionally, when reading the data back into a program, it can be quickly and efficiently converted back into a usable form. Serializable format is not relevant for storing and working with numbers in a fixed record size file.

Question 16

The readDouble and writeDouble methods of the RandomAccessFile class, process double precision floating-point numbers as ____ quantities.
A)ten-byte
B)two-byte
C)four-byte
D)eight-byte

Accepted Answer

Double precision floating-point numbers are 8-byte quantities, therefore the best choice is option D.

Question 17

Which statement about object streams is NOT correct?
A)Use object input streams to load the saved objects.
B)You must cast the returned result from the readObject method.
C)Any object can be saved to an object output stream.
D)Use object output streams to save all instance variables of an object automatically.

Accepted Answer

Not every object can be saved to an object output stream; the object must implement the Serializable interface to be eligible for serialization.

Question 18

What do we call the measure in bytes of the file pointer from the beginning of a RandomAccessFile?
A)size
B)seek
C)latency
D)offset

Accepted Answer

The measure in bytes of the file pointer from the beginning of a RandomAccessFile is known as the offset.

Question 19

Which is not a method available in the RandomAccessFile class?
A)readDouble
B)open
C)readInt
D)close

Accepted Answer

The RandomAccessFile class does not have a method named "open". This is because the object of the RandomAccessFile class is created by passing a file path to it. Thus, the "open" functionality is inherently included in the constructor of the class. The other options (readDouble, readInt, and close) are all valid methods available in the RandomAccessFile class.

Question 20

Which method moves the file pointer in a RandomAccessFile?
A)close
B)seek
C)length
D)getFilePointer

Accepted Answer

The method seek() is used to move the file pointer to a specified position in the RandomAccessFile. The other methods listed do not affect the position of the file pointer.

Quiz 21: Advanced Input/Output

In which of the following modes can a RandomAccessFile be opened? i.r II.rw III.w

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

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 24th record, which expression represents the offset to the beginning of the 25th record?

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 25th record?

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

Which is NOT a method in the RandomAccessFile class?

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

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

Which method in the RandomAccessFile class provides for random access?

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") ;

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

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

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

Which statement about object streams is NOT correct?

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

Which is not a method available in the RandomAccessFile class?

Which method moves the file pointer in a RandomAccessFile?