File Handling Demo

FileHandlingDemo.java

/*
 * File Handling Demo
 *
 * Is all about reading and writing activities over file system (java.io).
 * Streams provide communication channels between communication participants.
 *
 * Type of stream classes:
 *   * Byte Stream classes:
 *     - do not support Unicode
 *   * Character Stream classes:
 *     - they do support Unicode
 * Both:
 *     - support for InputStream & OutputStream (FileInputStream, ObjectInputStream)
 *     - support for Reader & Writer
 *
 * Usage:
 *   javac FileHandlingDemo.java
 *   java WriteToFileDemo
 *   java ReadFromFileDemo
 *   java FileReaderDemo
 */

import java.io.*;

class WriteToFileDemo {
  public static void main(String[] args) throws Exception {
    FileOutputStream fos = new FileOutputStream("NewFile.txt");
    // FileOutputStream fos = new FileOutputStream("NewFile.txt", true); // Append mode.
    fos.write("My message" . getBytes()); // getBytes() - Encodes String into a sequence of bytes
    System.out.println("File created.");
  }
}

class ReadFromFileDemo {
  public static void main(String[] args) throws Exception {
    FileInputStream fis = new FileInputStream("NewFile.txt");

    int ch;

    while ((ch = fis.read()) != -1) {
      System.out.print((char)ch);
    } // end of while
  }
}

class FileReaderDemo {
  public static void main(String[] args) throws Exception {
    FileReader fr = new FileReader("NewFile.txt");
    BufferedReader br = new BufferedReader(fr);

    String line;

    while ((line = br.readLine()) != null) {
      System.out.println(line);
    }

  }
}