Java File Handling

Question 1

Which package contains the File class?

Answer 1

The java.io class

Question 2

What is the syntax to import the file class?

Answer 2

import java.io.File; // Import the File class

Question 3

What is the syntax for specifying a new file?

Answer 3

File myObj = new File(“filename.txt”); // Specify the filename

Question 4

What are some of the most often used methods on the file class?

Answer 4

canRead() , canWrite(), createNewFile() , delete() , exists() , getName() , length() , mkdir()

Question 5

What is the syntax to import an exception?

Answer 5

import java.io.IOException; // Import the IOException class to handle errors

Question 6

What class needs to be imported to write to a file?

Answer 6

import java.io.FileWriter; // Import the FileWriter class

Question 7

What is the syntax to make the file to be writable?

Answer 7

FileWriter myWriter = new FileWriter(“filename.txt”);

Question 8

What is the method to write to a file?

Answer 8

write()

Question 9

What is the syntax to write to a file?

Answer 9

FileWriter myWriter = new FileWriter(“filename.txt”);
myWriter.write(“Files in Java might be tricky, but it is fun enough!”);
myWriter.close();

Question 10

What class is used to read contents of a text file?

Answer 10

Scanner class

Question 11

What is the syntax to import the Scanner class?

Answer 11

import java.util.Scanner; // Import the Scanner class to read text files

Question 12

What is the syntax to read a file?

Answer 12

File myObj = new File("filename.txt");
      Scanner myReader = new Scanner(myObj);
      while (myReader.hasNextLine()) {
        String data = myReader.nextLine();
        System.out.println(data);
      }
      myReader.close();

Question 13

What are some of the methods and syntax to get more information about a file?

Answer 13

File myObj = new File("filename.txt");
    if (myObj.exists()) {
      System.out.println("File name: " + myObj.getName());
      System.out.println("Absolute path: " + myObj.getAbsolutePath());
      System.out.println("Writeable: " + myObj.canWrite());
      System.out.println("Readable " + myObj.canRead());
      System.out.println("File size in bytes " + myObj.length());

Question 14

What is the syntax to delete a file?

Answer 14

import java.io.File; // Import the File class

public class DeleteFile {
  public static void main(String[] args) { 
    File myObj = new File("filename.txt"); 
    if (myObj.delete()) { 
      System.out.println("Deleted the file: " + myObj.getName());
    } else {
      System.out.println("Failed to delete the file.");
    } 
  } 
}

Question 15

What is the syntax to delete a folder?

Answer 15

import java.io.File;

public class DeleteFolder {
  public static void main(String[] args) { 
    File myObj = new File("C:\\Users\\MyName\\Test"); 
    if (myObj.delete()) { 
      System.out.println("Deleted the folder: " + myObj.getName());
    } else {
      System.out.println("Failed to delete the folder.");
    } 
  } 
}

Question 16

What is the file class?

Answer 16

The File class is Java’s representation of a file or directory path name. Because file and directory names have different formats on different platforms, a simple string is not adequate to name them. The File class contains several methods for working with the path name, deleting and renaming files, creating new directories, listing the contents of a directory, and determining several common attributes of files and directories.

It is an abstract representation of file and directory pathnames.
A pathname, whether abstract or in string form can be either absolute or relative. The parent of an abstract pathname may be obtained by invoking the getParent() method of this class.
First of all, we should create the File class object by passing the filename or directory name to it. A file system may implement restrictions to certain operations on the actual file-system object, such as reading, writing, and executing. These restrictions are collectively known as access permissions.
Instances of the File class are immutable; that is, once created, the abstract pathname represented by a File object will never change.

Question 17

What are some of the constructor options?

Answer 17

Constructors

File(File parent, String child) : Creates a new File instance from a parent abstract pathname and a child pathname string.
File(String pathname) : Creates a new File instance by converting the given pathname string into an abstract pathname.
File(String parent, String child) : Creates a new File instance from a parent pathname string and a child pathname string.
File(URI uri) : Creates a new File instance by converting the given file: URI into an abstract pathname.

Question 18

What is another way to create a new file with the file output stream?

Answer 18

String data = “Test data”;

FileOutputStream out = new FileOutputStream(“c://temp//testFile2.txt”);

out. write(data.getBytes());
out. close();

Question 19

What are the steps to create a file?

Answer 19

1 Need to import file Class from java.io
2 New to create a new file and input string to define where file to be stored
3 Run the create file method

Question 20

How to create a file in Java 8?

Answer 20

//Get the file reference
Path path = Paths.get("c:/output.txt");

//Use try-with-resource to get auto-closeable writer instance
try (BufferedWriter writer = Files.newBufferedWriter(path)) 
{
    writer.write("Hello World !!");
}

Question 21

What is a stream?

Answer 21

Is how data is handled in Java and is a stream of data

Question 22

What is the method to write to a file?

Answer 22

Buffereed writer class with FileWriter bw.write
bw.newLine()

Question 23

How to read a file?

Answer 23

BufferedReader, FileReader and then loop over the line, readLine and it will read all of the lines

Question 24

What are the two classes to read files?

Answer 24

BufferedReader & Scanner class