Input output and file handling in java

• 1. Concept of Streams
• 2. Types of Streams
• 3. The Console
• 4. InputStream
• 5. OutputStream
• 6. Reader
• 7. Writer
• 8. File
• 9. FileInputStream
• 10. FileOutputStream
• 11. FileReader
• 12. FileWriter

Java Input/Output (I/O)

1. Concept of Streams

• Stream: A sequence of data (bytes/characters) flowing from a source to a destination.
• Categories:
  • Input Stream: Reads data.
  • Output Stream: Writes data.

---

2. Types of Streams

1. Byte Streams:

   • Handles binary data.

   • Classes: InputStream and OutputStream.

   • Example:

     FileInputStream fis = new FileInputStream("file.txt");
     int data = fis.read();

2. Character Streams:

   • Handles text data.

   • Classes: Reader and Writer.

   • Example:

     FileReader fr = new FileReader("file.txt");
     int charData = fr.read();

---

3. The Console

1. System.err:

   • Outputs error messages.

   • Example:

     System.err.println("Error occurred!");

2. System.out:

   • Outputs normal messages.

   • Example:

     System.out.println("Hello, World!");

3. System.in:

   • Reads input from the user.

   • Example:

     Scanner sc = new Scanner(System.in);
     String input = sc.nextLine();

---

4. InputStream

• Purpose: Reads bytes from a source.

• Common Methods:

  • read(): Reads one byte.
  • close(): Closes the stream.

• Example:

  InputStream is = new FileInputStream("file.txt");
  int byteData = is.read();

---

5. OutputStream

• Purpose: Writes bytes to a destination.

• Common Methods:

  • write(int b): Writes one byte.
  • flush(): Flushes the stream.

• Example:

  OutputStream os = new FileOutputStream("file.txt");
  os.write(65); // Writes 'A'

---

6. Reader

• Purpose: Reads characters from a source.

• Common Methods:

  • read(): Reads one character.
  • close(): Closes the stream.

• Example:

  Reader reader = new FileReader("file.txt");
  int charData = reader.read();

---

7. Writer

• Purpose: Writes characters to a destination.

• Common Methods:

  • write(String str): Writes a string.
  • close(): Closes the stream.

• Example:

  Writer writer = new FileWriter("file.txt");
  writer.write("Hello!");

---

8. File

• Purpose: Represents file/directory paths.

• Key Methods:

  • exists(): Checks file existence.
  • createNewFile(): Creates a file.

• Example:

  File file = new File("file.txt");
  boolean exists = file.exists();

---

9. FileInputStream

• Purpose: Reads bytes from a file.

• Example:

  FileInputStream fis = new FileInputStream("file.txt");
  int data = fis.read();
  fis.close();

---

10. FileOutputStream

• Purpose: Writes bytes to a file.

• Example:

  FileOutputStream fos = new FileOutputStream("file.txt");
  fos.write(65); // Writes 'A'
  fos.close();

---

11. FileReader

• Purpose: Reads characters from a file.

• Example:

  FileReader fr = new FileReader("file.txt");
  int charData = fr.read();
  fr.close();

---

12. FileWriter

• Purpose: Writes characters to a file.

• Example:

  FileWriter fw = new FileWriter("file.txt");
  fw.write("Hello, World!");
  fw.close();

Let me know if you need a complete program with these concepts!