Question 1

What interface must a class implement to indicate that objects of the class can be output and input as a stream of bytes?
A)Synchronize
B)Deserializable
C)Serializable
D)ObjectOutput

Accepted Answer

The Serializable interface must be implemented to indicate that objects of the class can be output and input as a stream of bytes using serialization. Serialization is the process of converting an object into a stream of bytes, which can then be stored in a file or transmitted over a network. The Serializable interface is empty and serves only to identify the semantics of being serializable. It has no methods to be implemented.

Question 2

How do methods setIn,setOut and setErr affect the standard input,output and error streams?
A)They output data to the standard input,output and error streams.
B)They provide the only way to access the standard input,output and error streams.
C)They redirect the standard input,output and error streams.
D)They empty the standard input,output and error streams.

Accepted Answer

The methods setIn, setOut, and setErr are used to redirect the standard input, output, and error streams respectively. This means that any data that would have been read from or written to these streams will now be read from or written to the streams that have been set using these methods. This redirection can be useful in situations where the default behavior of the standard input, output, or error streams needs to be modified.

Question 3

Which of the following classes is not used for file input?
A)FileInputStream
B)FileReader
C)ObjectInputStream
D)Formatter

Accepted Answer

Formatter is used for formatting and outputting data, not for file input. FileInputStream, FileReader, and ObjectInputStream are all used for reading data from files.

Question 4

Which of the following statements is false?
A)A DirectoryStream enables a program to iterate through the contents of a directory.
B)Character-based input and output can be performed with classes Scanner and Formatter.
C)A relative path contains all the directories,starting with the root directory,that lead to a specific file or directory.
D)Every file or directory on a disk drive has the same root directory in its path.

Accepted Answer

A relative path specifies a location starting from the current directory and does not need to start from the root directory. Absolute paths, not relative paths, start with the root directory.

Question 5

Which of the following statements is false?
A)Path method isAbsolute returns a boolean indicating whether a Path represents an absolute path to a file or directory.
B)Files static method getLastModifiedTime receives a Path and returns a FileTime (package java.nio.file.attribute)indicating when the file was last modified.
C)Files static method size receives a Path and returns a long representing the number of bytes in the file or directory.For directories,the value returned is platform specific.
D)All of the above are true.

Accepted Answer

All the statements provided are true. Statement A correctly describes the isAbsolute method for Path objects. Statement B accurately describes the getLastModifiedTime method of the Files class. Statement C correctly describes the size method of the Files class, including the platform-specific behavior for directories.

Question 6

Files static method ________ receives a Path and returns a boolean indicating whether that Path represents a directory on disk.
A)isDiskDirectory
B)isDirectory
C)isFileDirectory
D)isPath

Accepted Answer

The correct method is "isDirectory". This method checks if the given path represents a directory on the disk and returns a boolean value accordingly. The other options are not valid methods and do not exist in the Files class.

Question 7

Path method ________ returns the String name of a file or directory without any location information.
A)getStringName
B)getFileOrDirectoryName
C)getDirectoryName
D)getFileName

Accepted Answer

The getFileName method returns the name of the file or directory without any location information.

Question 8

Which statement regarding Java files is false?
A)Java imposes no structure on a file.
B)Notions like "record" do not exist in Java files.
C)The programmer must structure files to meet the requirements of applications.
D)Records in a Java sequential file are stored in order by record key.

Accepted Answer

Java does not inherently support the concept of records stored in order by a record key within its file system operations. The handling of how data is structured, including any sorting or ordering, is up to the programmer to implement in their application code. Java files themselves are treated as streams of bytes, and any notion of records or their ordering is a higher-level abstraction not provided by the Java file I/O APIs directly.

Question 9

Records in a sequential file are not usually updated in place.Instead ________.
A)the updated data is placed in a "surrogate" file
B)the entire file is usually rewritten
C)the file is truncated
D)The above statement is false-records in sequential files are usually updated in place.

Accepted Answer

In a sequential file, data is written in a continuous stream, which means accessing a single record in the middle of the file can be time-consuming. Therefore, updating a record in a sequential file usually involves rewriting the entire file. The updated version of the record is written in its new location within the new file, and the old version of the record is deleted. This process is time-consuming but ensures that the data in the file is always up-to-date.

Question 10

Which of the following statements is true?
A)Class Scanner provides the ability to reposition to the beginning of a file with method seek.
B)Class Scanner provides the ability to reposition to the beginning of a file with method reposition.
C)Class Scanner does not provide the ability to reposition to the beginning of the file.
D)If it is necessary to read a sequential file again,the program can simply keep reading-when the end of the file is reached,the Scanner is automatically set to point back to the beginning of the file.

Accepted Answer

Class Scanner does not provide the ability to reposition to the beginning of the file. It only allows reading sequentially from the current position in the file.

Question 11

When all the contents of a file are truncated,this means that ________.
A)the data in the file is saved to a backup file
B)the file is deleted
C)a FileNotFoundException occurs
D)all the data in the file is discarded

Accepted Answer

When a file is truncated, it means that all the data in the file is deleted or discarded. There is no backup file or exception thrown, it simply empties the contents of the file.

Question 12

Adding the services of one stream to another is known as ________.
A)chaining
B)wrapping
C)adding
D)sequencing

Accepted Answer

The answer of Adding the services of one stream to...

Question 13

Which of the following classes enable input and output of entire objects to or from a file?
a)SerializedInputStream
b)SerializedOutputStream
c)ObjectInputStream
d)ObjectOutputStream
e)Scanner
f)Formatter
A)A and B.
B)C and D.
C)C,D,E,F.
D)E and F.

Accepted Answer

ObjectInputStream and ObjectOutputStream classes enable input and output of entire objects to or from a file through serialization. SerializedInputStream and SerializedOutputStream classes do not exist in Java. Scanner and Formatter classes allow input and output of formatted text, but not entire objects.

Question 14

Class ________ provides static methods for common file and directory manipulations,including methods for copying files;creating and deleting files and directories;getting information about files and directories;reading the contents of files;getting objects that allow you to manipulate the contents of files and directories;and more.
A)File
B)FileAndDirectory
C)Files
D)FilesAndDirectories

Accepted Answer

The correct answer is C) Files. The java.nio.file.Files class provides static methods for various file and directory operations, such as copying, creating, deleting, and reading files, as well as getting information about them.

Question 15

Streams that input bytes from and output bytes to files are known as ________.
A)bit-based streams
B)byte-based streams
C)character-based streams
D)Unicode-based streams

Accepted Answer

Byte-based streams specifically deal with inputting and outputting bytes from files. The other options are not as specific and could include different types of streams that do not necessarily deal with files.

Question 16

Which of the following statements is false?
A)Storage of data variables and arrays is temporary.
B)Data is lost when a local variable "goes out of scope."
C)Files are used for long-term retention of large amounts of data.
D)Data maintained in files is often called transient data.

Accepted Answer

Data maintained in files is not often called transient data. Transient data refers to data that is only temporarily needed and is not meant to be stored long-term. Files are used for long-term retention of large amounts of data, so the statement in option D is false. Options A, B, and C are true statements.

Question 17

A(n)________ path starts from the directory in which the application began executing.
A)absolute
B)relative
C)parallel
D)comparative

Accepted Answer

A relative path is a path that starts from the current directory or working directory. In this case, since the application began executing in a certain directory, a relative path would start from that directory. Absolute paths would start from the root directory. Parallel and comparative paths are not relevant in this context.

Question 18

What does the following statement do?
Scanner scanner = new Scanner(Paths.get("test.txt"));
A)Opens a binary file for input.
B)Opens a binary file for output.
C)Opens a text file for input.
D)Opens a text file for output.

Accepted Answer

The statement creates a Scanner object and uses the Paths class to retrieve the path of the "test.txt" file, which is then opened for input. Since the file is being read, it is assumed to be a text file rather than a binary file.

Question 19

Which of the following statements is false?
A)A Path represents the location of a file or directory.
B)Path objects open files and provide file-processing capabilities.
C)Class Paths is used to get a Path object representing a file or directory location.
D)The static method get of class Paths converts a String representing a file's or directory's location into a Path object.

Accepted Answer

Path objects represent the location of a file or directory and provide file-processing capabilities, but they do not open files. Opening and processing files require other classes such as FileInputStream and BufferedReader.

Question 20

A serialized object is ________.
A)an object represented as a sequence of bytes used to store the object's data in a file
B)an object in memory that has been recreated from data in a file
C)a standard output stream object used to convert objects in code to data in a file
D)None of the above.

Accepted Answer

A serialized object is an object represented as a sequence of bytes used to store the object's data in a file. It can be later deserialized, which means it can be recreated in memory from the stored data in the file. Option B is incorrect because a deserialized object is created in memory, not a serialized object. Option C refers to an output stream used to write data to a file, but not specifically for serializing objects. Option D is incorrect because there is a correct answer among the choices.

Quiz 15: Files,streams and Object Serialization

What interface must a class implement to indicate that objects of the class can be output and input as a stream of bytes?

How do methods setIn,setOut and setErr affect the standard input,output and error streams?

Which of the following classes is not used for file input?

Which of the following statements is false?

Which of the following statements is false?

Files static method ________ receives a Path and returns a boolean indicating whether that Path represents a directory on disk.

Path method ________ returns the String name of a file or directory without any location information.

Which statement regarding Java files is false?

Records in a sequential file are not usually updated in place.Instead ________.

Which of the following statements is true?

When all the contents of a file are truncated,this means that ________.

Adding the services of one stream to another is known as ________.

Which of the following classes enable input and output of entire objects to or from a file? a) SerializedInputStream b) SerializedOutputStream c) ObjectInputStream d) ObjectOutputStream e) Scanner f) Formatter

Streams that input bytes from and output bytes to files are known as ________.

Which of the following statements is false?

A(n) ________ path starts from the directory in which the application began executing.

What does the following statement do? Scanner scanner = new Scanner(Paths.get("test.txt") ) ;

Which of the following statements is false?

A serialized object is ________.