Java I/O Streams and File Handling

Streams

• A stream is an object that represents data being delivered to or from an object, one byte or character at a time.
• There are two kinds of streams: Byte Streams and Character Streams (also known as "readers" and "writers").
• Byte Streams read and write raw bytes, while Character Streams read and write characters (16-bit Unicode).

Readers and Writers

• Readers and Writers are Character Streams that read and write characters.
• Examples of Readers and Writers include FileReader, FileWriter, and PrintWriter.

Buffering

• Buffering is used to improve performance when accessing data outside of memory (e.g., disk, network, web).
• It is more efficient to access a large chunk of data at once rather than one byte or character at a time.

LineNumberReader

• A LineNumberReader is a buffered character-input stream that keeps track of line numbers.
• The setLineNumber() method does not seek to a line in the file, but rather designates the line number of the first line.

InputStreamReader and PrintWriter

• InputStreamReader converts bytes from an InputStream to characters, using the proper encoding.
• PrintWriter prints formatted representations of objects to a text-output stream.
• System.out is a PrintWriter.

Using Streams on the Web

• Streams can be used to read from a URL object, URLConnection object, and write to a URLConnection object or HttpServletResponse object.

File

• A File object is a wrapper for a String, and does not necessarily denote something on the file system.
• A File object can be created with any string, regardless of whether it's a valid filename or not.