Describe the function of File class? Create a DataInputStream for a file name "purbanchal.dat" and store "I am student of BIT VI semester" in that file.

 The File class in Java provides methods for working with files and directories. It allows you to create, delete, rename, and move files and directories, as well as retrieve information about them such as their size, creation time, and last modified time. It also provides methods for testing whether a file or directory exists, and whether it is readable, writable, or executable.

To create a DataInputStream for a file named "purbanchal.dat" and store the string "I am a student of BIT VI semester" in that file, you can use the following code:

import java.io.*;
public class DataInputStreamExample {
    public static void main(String[] args) {
        String filename = "purbanchal.dat";
        String message = "I am a student of BIT VI semester";
        try {
            // create a new file
            File file = new File(filename);
            // create a new DataOutputStream to write to the file
            DataOutputStream out = new DataOutputStream(new FileOutputStream(file));
            // write the message to the file
            out.writeUTF(message);
            out.close();
            // create a new DataInputStream to read from the file
            DataInputStream in = new DataInputStream(new FileInputStream(file));
            // read the message from the file
            String readMessage = in.readUTF();
            System.out.println("Message read from file: " + readMessage);
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

In this code, we create a new File object with the name "purbanchal.dat". We then create a new DataOutputStream to write to the file and use its writeUTF method to write the string "I am a student of BIT VI semester" to the file. We then close the DataOutputStream.

Next, we create a new DataInputStream to read from the file and use its readUTF method to read the message from the file. We then print the message to the console and close the DataInputStream.

When you run this program, it will create a new file named "purbanchal.dat" in the current directory (or overwrite the file if it already exists). It will then write the string "I am a student of BIT VI semester" to the file using a DataOutputStream, and read the same string back from the file using a DataInputStream. Finally, it will print the string to the console.