File Manipulation

Question 1

A class that allows you to open a file for writing. It also allows you to write data to the file using the same print and println methods that you have been using to display data on the screen.

Answer 1

PrintWriter class

Question 2

The name of the file that you wish to open is passed as a what?

Answer 2

Passed as a string

Question 3

To where is the name of the file that you wish to open passed to?

Answer 3

To the PrintWriter class’s constructor

Question 4

Syntax for creating an empty text file named StudentData.txt and establish a connection between it and the PrintWriter object named outputFile

Answer 4

PrintWriter outputFile = new PrintWriter(“StudentData.txt”);

Question 5

Where will the file named StudentData.txt be created?
PrintWriter outputFile = new PrintWriter(“StudentData.txt”);

Answer 5

The file will be created in the current directory or folder.

Question 6

TRUE OR FALSE?
When the program is finished writing data to the file, it must close the file.

Answer 6

TRUE

Question 7

How do you write data to a file using the Print Writer?

Answer 7

outputFile.println(“Jim”)

Question 8

How can you make the program close the file after it is finished writing data to the file?

Answer 8

outputFile.close();

Question 9

It is what the program throws when an unexpected event occurs in a Java program.

Answer 9

Exception

Question 10

What happens when the main method throws an exception?

Answer 10

The program halts and an error message is displayed.

Question 11

TRUE OR FALSE?
“PrintWriter objects are capable of throwing exceptions.”

Answer 11

TRUE

Question 12

How do you allow a method to rethrow an exception that has not been dealt with?

Answer 12

Write a throws clause in the method header

Question 13

Syntax for writing a throws clause in the method header

Answer 13

public static void main(String[] args) throws IOException

Question 14

What would the output in the StudentData.txt file be?
import java.io*;
public class FileManipulation {
public static void main(String[] args) throws IOException {
PrintWriter outputFile = new PrintWriter(“StudentData.txt”);
outputFile.println(“Jim”);
outputFile.println(“95”);
outputFile.println(“Karen”);
outputFile.println(“98”);
outputFile.println(“Bob”);
outputFile.println(“82”);
outputFile.close();
}
}

Answer 14

Jim
95
Karen
98
Bob
82

Question 15

What are the 2 basic steps when writing a program that writes data to a file?

Answer 15

1. You need the import java.io.* statement at the top section of your program.
2. Create a PrintWriter object and pass the name of the file as a string to the constructor

Question 16

Means writing new data to the end of the data that already exists in the file?

Answer 16

Appending

Question 17

How many arguments do you need to pass to the FileWriter constructor to append data to an existing file?

Answer 17

2

Question 18

Syntax for creating an instance of the FileWriter class and passing 2 arguments to the constructor.

Answer 18

FileWriter fwriter = new FileWriter(“MyFriends.txt”, true);

Question 19

Syntax for creating a PrintWriter object to pass a reference to the Filewriter as an argument to the PrintWriter constructor.

Answer 19

FileWriter fwriter = new FileWriter(“MyFriends.txt”, true);
PrintWriter outputFile = new PrintWriter(fwriter);

Question 20

Class used to read input from a file.

Answer 20

Scanner class

Question 21

Syntax for passing a reference to a File object?

Answer 21

File myFile = newFilw(“Customers.txt”);
Scanner inputFile = new Scanner(myFile);

Question 22

How do you close the file using the Scanner class’s close method?

Answer 22

inputFile.close();

Question 23

Reads a line of input and returns the line as a string

Answer 23

Scanner class’s nextLine method

Question 24

CONTENT OF subject.txt
math
science
english
What would the output be?

CODE
File myFile = new File(“subject.txt”);
Scanner inputFile = new Scanner(myFile);
subject = inputFile.nextLine();
System.out.println(“The first subject is “ + subject);

subject = inputFile.nextLine();

System.out.println(“The second subject is “ + subject);

subject = inputFile.nextLine();

System.out.println(“The third subject is “ + subject);

subject = inputFile.nextLine();

Answer 24

OUTPUT
The first subject is math
The second subject is science
The third subject is english

Question 25

What are the 2 arguments that need to be passed to the FileWriter constructor to append data to an existing file?

Answer 25

1. a string containing the name of the file
2. the boolean value true

Question 26

a signal indicating that the program cannot continue until the unexpected event has been dealt with.

Answer 26

Exception