Notes

java organizes I/O into byte and character streams, each with specific class for different tasks.

byte stream

• handle raw binary data
• base classes
  • InputStream - Abstract class for reading bytes
  • OutputStream - Abstract class for writing bytes
• common subclasses -
  • FileInputStream, FileOutputStream - read/write bytes from/to files.
  • BufferedInputStream, BufferedOutputStream- use buffering to reduce direct access to the underlying system.
  • DataInputStream, DataOutputStream - read/write primitive data types
  • ObjectInputStream, ObjectOutputStream - serialize/deserialize objects.

import java.io.*;

public class ByteStreamExample {
    public static void main(String[] args) {
        try (FileInputStream fis = new FileInputStream("input.txt");
             FileOutputStream fos = new FileOutputStream("output.txt")) {
            int byteData;
            while ((byteData = fis.read()) != -1) { // Read byte-by-byte
                fos.write(byteData); // Write byte
            }
        } catch (IOException e) {
            System.out.println("IO Error: " + e.getMessage());
        }
    }
}

character streams

• handles unicode characters, ideal for text data.
• base classes -
  • Reader - abstract class for reading characters
  • Writer - abstract class for writing characters.
• common subclasses -
  • FileReader, FileWriter - read/write characters to/from files.
  • BufferedReader, BufferedWriter - buffer characters data for efficiency.
  • InputStreamReader, OutputStreamWriter - bridge bytes streams to character streams

import java.io.*;

public class CharStreamExample {
    public static void main(String[] args) {
        try (BufferedReader reader = new BufferedReader(new FileReader("input.txt"));
             BufferedWriter writer = new BufferedWriter(new FileWriter("output.txt"))) {
            String line;
            while ((line = reader.readLine()) != null) {
                writer.write(line);
                writer.newLine();
            }
        } catch (IOException e) {
            System.out.println("IO Error: " + e.getMessage());
        }
    }
}

predefined streams

• system.in
• system.out
• system.err