File I/O - Java - page 544

Self-Test Exercises
11. Might the following throw an exception that needs to be caught or declared in a
throws clause?

Scanner inputStream =
new Scanner( new FileInputStream("morestuff.txt"));

(The stream inputStream would be used to read from the text file
morestuff.txt .)

Reading a Text File Using BufferedReader
Until the Scanner class was introduced with version 5.0 of Java, the class Buffered-Reader
was the preferred stream class to use for reading from a text file. It is still a commonly used
class for reading from a text file. The use of BufferedReader is illustrated in Display 10.7,
which contains a program that reads two lines from a text file named morestuff2.txt and
writes them back to the screen. The file morestuff2.txt is a text file that a person could
have created with a text editor or that a Java program could have created using PrintWriter .
The program opens the text file morestuff2.txt as follows:

Buffered-
Reader

opening a file

BufferedReader inputStream =
new BufferedReader( new FileReader("morestuff2.txt"));

The class BufferedReader , like the classes PrintWriter and Scanner , has no con-
structor that takes a file name as its argument, so we need to use another class—in this
case, the class FileReader —to convert the file name to an object that can be an argu-
ment to BufferedReader .
An object of the class BufferedReader that is connected to a text file, as in Display
10.7, has a method named readLine that is like the method nextLine of the Scanner
class. This use of readLine to read from a text file is illustrated in Display 10.7.
Display 10.8 describes some of the methods in the class BufferedReader . Notice
that there are only two methods for reading from a text file, readLine and read . We
have already discussed readLine .

readLine

Display 10.7 Reading Input from a Text File Using BufferedReader (part 1 of 2)

1 import java.io.BufferedReader;

2 import java.io.FileReader;

3 import java.io.FileNotFoundException;

4 import java.io.IOException;

5 public class TextFileInputDemo
6{
7 public static void main(String[] args)

8 {