/** This short program practices file input and output.  Generally there are
 * three steps to doing file I/O:
 * 1.  Set up the input and output "streams" to refer to the relevant files.
 * 2.  Read lines of text, parse them as needed.  The BufferedReader class
 *     includes functions that allow us to read individual characters, or
 *     whole lines, but nothing else.  On the other hand, for output, the
 *     PrintWriter is more flexible -- we can write values or objects as we
 *     would normally do with the Screen.
 * 3.  Close the streams when done.
 * The reason why we use buffers to handle file I/O is because of efficiency.
 * The basic FileReader and FileWriter are designed only to handle individual
 * bytes, and often we have lots of data to read or write.  A buffer is an
 * area within main memory that acts like a "waiting room" for data transfers
 * between the program and disk.  For instance, for output, we collect the
 * output in the output buffer until it's time to finally write to disk, which
 * takes place with a call to flush() or close().
 */

import java.io.*;

public class FileIO
{
  public static void main(String [] args) throws IOException
  {
    // set up files for input and output
    BufferedReader input = new BufferedReader(new FileReader("coleridge.txt"));
    PrintWriter output = new PrintWriter(new FileWriter("stats.txt"));

    // process the input -- read lines one at a time, and determine their length
    // In a more sophisticated application, we would actually parse the
    // input line using a StringTokenizer.
    // Note that we don't know in advance how many lines there are, so we
    // read until the readLine() function returns null (meaning no more input)
    // Notice the output goes to a file.
    int lineNumber = 0;
    while (true)
    {
      String line = input.readLine();
      if (line == null)
        break;
      ++lineNumber;
      output.println("Length of line " + lineNumber + " is " + line.length());
    }

    // Close the streams.
    input.close();
    output.close();
  }
}