• Text files (.txt)
• XML files (.xml)
• JSON files (.json)
• CSV files (.csv)

1. Reader (for reading characters)
2. Writer (for writing characters)

import java.io.FileReader;
import java.io.IOException;

public class ReadFileUsingReader
{
    public static void main(String[] args)
    {
        try
        {
            // Open file for reading
            FileReader fr = new FileReader("d://aaa.txt");
            int i;
            
            System.out.println("----- Reading data from file using FileReader -----");
            while ((i = fr.read()) != -1)
            {
                System.out.print((char) i); // read character by character
            }
            
            fr.close();
        }
        catch (IOException e)
        {
            System.out.println("Error reading file: " + e.getMessage());
        }
    }
}

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

public class WriteFileUsingWriter
{
    public static void main(String[] args)
    {
        try
        {
            // Open file for writing
            FileWriter fw = new FileWriter("d://bbb.txt");
            
            String data = "Hello, this is my first Java Program using FileWriter to write data in file....";
            fw.write(data); // write string directly
            
            fw.close();
            System.out.println("Data successfully written to bbb.txt");
        }
        catch (IOException e)
        {
            System.out.println("Error writing file: " + e.getMessage());
        }
    }
}