Files Read/Write 

Read a File:

We can also read the contents of a file in java. This is done using the scanner class. This method throws an FileNotFoundException if any error occurs. Hence it is important  to write it in a try…….catch block.

Example:

import java.io.File;
import java.io.FileNotFoundException;  
import java.util.Scanner;

public class ReadFile {
    public static void main(String[] args) {
        try {
            File file = new File("students.txt");
            Scanner myReader = new Scanner(file);
            while (myReader.hasNextLine()) {
                String data = myReader.nextLine();
                System.out.println(data);
            }
            myReader.close();
        } catch (FileNotFoundException e) {
            System.out.println("Error.....");
            e.printStackTrace();
        }
    }
}

Output:

Here we do not see an output, because the stundents.txt file created has no content. 

Let’s read a file which has some content in it.

Example:

import java.io.File;
import java.io.FileNotFoundException;  
import java.util.Scanner;

public class ReadFile {
    public static void main(String[] args) {
        try {
            File file = new File("Teachers.txt");
            Scanner myReader = new Scanner(file);
            while (myReader.hasNextLine()) {
                String data = myReader.nextLine();
                System.out.println(data);
            }
            myReader.close();
        } catch (FileNotFoundException e) {
            System.out.println("Error.....");
            e.printStackTrace();
        }
    }
}

 

Output:

This file has information of TeachersName: Rosy Fernandes, Age: 36Name: Isha Mheta, Age: 29

 

Write a File:

We use the FileWriter class to write into a file in java.

Example:

import java.io.FileWriter;  
import java.io.IOException;

public class WriteFile {
    public static void main(String[] args) {
        try {
            FileWriter file = new FileWriter("Teachers.txt");
            file.write("This file has information of Teachers");
            file.write("Name: Rosy Fernandes, Age: 36");
            file.write("Name: Isha Mheta, Age: 29");
            file.close();
            System.out.println("File has been written into.");
        } catch (IOException e) {
            System.out.println("Error......");
            e.printStackTrace();
        }
    }
}

 

Output:

File has been written into.