File I/O - Java - page 549

Checking for the End of a Text File with BufferedReader
The method readLine of the class BufferedReader returns null when it tries to read
beyond the end of a text file. The method read of the class BufferedReader returns

− 1

when it tries to read beyond the end of a text file.

Display 10.9 Checking for the End of a Text File with BufferedReader (part 1 of 2)

1 import java.io.BufferedReader;

2 import java.io.FileReader;

3 import java.io.PrintWriter;

4 import java.io.FileOutputStream;

5 import java.io.FileNotFoundException;

6 import java.io.IOException;

7 /**

8 Makes numbered.txt the same as original.txt, but with each line numbered.

9 */

10 public class TextEOFDemo

11 {

12 public static void main(String[] args)

13 {

14 try

15 {

16 BufferedReader inputStream =

17 new BufferedReader( new FileReader("original.txt"));

18 PrintWriter outputStream =

19 new PrintWriter( new FileOutputStream("numbered.txt"));

20 int count = 0;

21 String line = inputStream.readLine();

22 while (line != null )

23 {

24 count++;

25 outputStream.println(count + " " + line);

26 line = inputStream.readLine();

27 }

28 inputStream.close();

29 outputStream.close();

30 }

31 catch (FileNotFoundException e)

32 {

(continued)